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Design of Experiments (DOE) and Other 6-Sigma Tools Used to Minimize Rear Door Opening Vibration on a Vehicle | Very often, engineering problems involve several variables that have different physical behavior making theoretical modeling complex and difficult. In the present paper, 6-Sigma tools were used to develop an experimental model that describes the system. The issue in focus was the vibration observed at the top of rear door during normal opening operation, causing the impression of a fragile structure. The resulting experimental model was able to explain door opening vibration with only 15% of error. In addition, it was possible to choose the best combination and setting for each variable in order to achieve a product benchmarking value. |
Passive Close-Off Feature for Sample Acquisition and Retention | The current coring bit and percussive drilling style works very well for strong rocks; however, when coring into weak, crumbling rock, the core tends to break apart and simply fall out of the bit. These rocks, powder, and other debris can have useful information that is lost when they fall out of the bit after the core has been made, as there is no retention feature in place. A retention mechanism for coring into weak rocks was developed. |
SPSCGR | SPSCGR generates a contact graph suitable for use by the ION (Interplanetary Overlay Network) DTN (Delay/Disruption Tolerant Network) implementation from data provided by the JPL SPS (Service Preparation System) Portal. Prior to SPSCGR, there was no way for a mission or other entity to route DTN traffic across the DSN without manually constructing a contact graph. SPSCGR automates this process of contact graph construction. |
Reactionless Drive Tube Sampling Device and Deployment Method | A sampling device and a deployment method were developed that allow collection of a predefined sample volume from up to a predefined depth, precise sampling site selection, and low impact on the deploying spacecraft. This device is accelerated toward the sampled body, penetrates the surface, closes a door mechanism to retain the sample, and ejects a sampling tube with the sample inside. At the same time the drive tube is accelerated, a sacrificial reaction mass can be accelerated in the opposite direction and released in space to minimize the momentum impact on the spacecraft. The energy required to accelerate both objects is sourced locally, and can be a spring, cold gas, electric, or pyrotechnic. After the sample tube is ejected or extracted from the drive tube, it can be presented for analysis or placed in a sample return capsule. |
Wallops Flight Facility 6U Advanced CubeSat Ejector (ACE) | Six-unit (6U) CubeSats are recognized as the next nanosatellite to be considered for standardization. The CubeSat standard established by California Polytechnic University (Cal Poly), which applies to 1U??U sizes, has proven to be a valuable asset to the community. It has both provided design guidelines to CubeSat developers and a consistent, low-risk interface to launch service providers. This has ultimately led to more flight opportunities for CubeSats. A similar path is desired for the 6U CubeSat. Through this process of standardization, a consistent, low-risk interface for the 6U needs to be established. |
The Future of Aircraft Electrification | A resounding applause fills an auditorium in Fort Worth, Texas, as engineers, researchers, and business leaders stand in unison to celebrate the closing keynote of another aerospace conference. Participants grab their belongings and file out into the street where they clamor for rides to the airport. I hail a cab and glance at my watch, noting that in 45 minutes, I'm expected at a meeting in Austin-about 200 miles away. Just then, a taxi pulls up to the curb. I step inside, and as soon the door closes, I'm up in the air. Fifteen minutes later, I land in Austin beside my car; I hop in and head to the meeting location. I arrive soon after, with time to spare. Stories like this were used in the past to paint a futuristic picture of the transportation industry. Visionaries would share them to entice businesses to invest in new modes of travel that, at the time, seemed only possible in dreams. |
SAE Electronics + Connectivity 2012-11-28 | Integration opens the door Semiconductor suppliers are integrating many functions into power devices while also cutting power consumption in an environment, automotive doors, where 8-bit microcontrollers still hold sway. |
Safety with Convenience: Applying Low Cost Obstacle Detection Technology to Powered Closure Systems with Express Motion | There is a growing market for Powered Closure Systems and a strong trend to incorporate express motion for convenience. This drives the need to incorporate obstacle detection using anti-pinch technology for safety reasons according to vehicle safety standards applicable in the governing region. Powered Closure systems include windows, sunroofs, rear hatches, trunk lids and sliding doors with other applications under consideration. This paper will investigate the application of the technology in a cost-effective manner to these systems. A brief comparison of technologies will be considered and the paper will review motor-based control to explore the range of conditions required for obstacle detection. The challenge to provide good protection for obstacle intrusion without causing inadvertent system reversals due to environmental conditions will be presented. A primary focus of the paper will discuss the development of a technology ?쐔oolbox??to allow adaptation for the various applications and system to system variation. There is some hesitancy in the market to introduce this available technology due to lack of understanding or concern over cost. This paper seeks to show that the uses of low cost technology can be applied to provide improved safety while increasing convenience to the vehicle operator. |
Innovative Thermoplastic Cavity Filler Design Solutions | The use of acoustic cavity fillers or ?쐀affles??to prevent the propagation of air borne and structure borne noise, water and dust into the interior spaces of vehicle structures has been in practice for many years. Continuous development of new OEM requirements has pushed the state of the art concerning the design and functionality of these cavity sealing systems. Various technologies are available to OEMs to provide sealing that will prevent water and dust penetration, maximize performance of vehicle HVAC systems, and minimize the propagation of noise from the body structure into the interior compartment under operating conditions. Generally, three types of cavity sealing systems are available: pre-formed thermoplastic-based systems that incorporate a heat reactive thermoplastic sealer applied to a nylon or steel ?쐁arrier??for attachment to the body structure; heat reactive rubber-based sealer systems that incorporate a carrier, push pin or pressure sensitive adhesive layer for attachment; and bulk applied chemically reactive two component polyurethane or expandable ?쐄oam??systems. In this case study, a challenge undertaken by this supplier was to provide a thermoplastic baffle design of equal or lesser weight compared to a competitive, die-cut rubber-based technology currently in production at a particular OEM, while achieving equivalent acoustical performance. This paper will document the alternative design proposals and development activities that were pursued to meet this particular objective. |
Optimization through NVH Analysis to Improve the Vehicle Acoustics and Quality of Transmission Shifter | Gear shift quality and feel determines the performance of the transmission. It is dependent on the synchronizer, shift system, gear shifter etc in a transmission. In this study the impact of the transmission shifter on the gear shift feel is detailed. More focus is paid towards the feel in terms of NVH characteristics. The rear wheel drive transmission shifter can be bifurcated into direct and indirect shift type. Indirect shifter are of two types, the rod type shifter and the cable shifter. The rod type shifter is analyzed in detail. All the shifters are connected to the gear shift top lever which is the customer interface for gear shifting. The design of the top lever is critical in getting the optimal feel of shifting and the mounting of the shifter is critical to improve its NVH characteristics. Different design iteration of the top lever are studied to illustrate the impact of the weight and stiffness on the vibration. CORRELATION OF A SEMI REMOTE SHIFTER MOUNTING ON VEHICLE ACOUSTICS AND VIBRATION is also established. The shifter dynamics are simulated and its NVH characteristics were studied for 4 cylinder engine and 3 cylinder engine. The shifter strength is analyzed with CAE on hyper mesh. The mechanical links involved and the iterations done to improve the shift quality as well the vibration levels of the hand ball are described. The biasing and shifting force and the travel of the knob in each gear are optimized by verifying through GSQA. Various rear wheel drive transmission have been used as an example to illustrate the shifter dynamics and efficiency. In a three cylinder engine the optimization of the semi remote shifter for the vibration and noise is critical. The solution can be common with a 4-cylinder engine if the arrangement is similar. The extent of benefit would be less on the 4-cylinder than with the 3-cylinder engine as it is more balanced. This study deals primarily with the mounting scheme of the semi remote shifter and its impact on the vehicle NVH. As the 3-cylinder engine configuration has the maximum drive train vibration, it enables a better understanding of the impact of the semi remote shifter mounting scheme on the vehicle. The analysis would help in the selection of the optimum semi remote shifter configuration and material with design adaptation suited to the engine configuration providing better NVH result on the vehicle. |
Vibro-Impact Analysis of Manual Transmission Gear Rattle and Its Sound Quality Evaluation | Experimental schemes, frequency characteristics, subjective and objective sound quality evaluation and sound quality prediction model establishment of a certain mass-production SUV (Sport Utility Vehicle, SUV) manual transmission gear rattle phenomenon were analyzed in this paper. Firstly, vehicle experiments, including experiment conditions, vibration acceleration sensor and microphone arrangements and especial considerations in experiments, were described in detail. Secondly, through time-frequency analysis, broadband characteristics of manual transmission gear rattle noise were identified and vibro-impact of gear rattle occurs in the frequency range of 450~4000Hz on the vehicle idle condition and the creeping condition. Thirdly, based on bandwidth filtering processing of gear rattle noise, subjective assessment experiments by a paired comparison method were carried out. Evaluation results passed triangular loop verification and Spearman correlation coefficient examination, and then subjective annoyance results of each noise sample were calculated. Further, objective evaluation results, based on two physical acoustics parameters and six psychological acoustics parameters, were obtained respectively. Finally, comprehensive evaluation of subjective and objective results was analyzed by the MLR (Multiple Linear Regression, MLR) method. It?셲 concluded that AI (Articulation Index) was the appropriate parameter that?셲 closely related to subjective annoyance results, and correlation coefficient of AI and subjective annoyance results was up to 0.948. Sound quality prediction model of gear rattle was then established on the vehicle idle condition and the creeping condition. Overall in this paper, research achievements could be adopted to solve practical engineering problems (especially gear rattle problem), and furthermore it could reduce R&D (Research and Design, R&D) cycle, labor costs and material costs dramatically. |
Systems Engineering Approach for Voice Recognition in the Car | In this paper, a systems engineering approach is explored to evaluate the effect of design parameters that contribute to the performance of the embedded Automatic Speech Recognition (ASR) engine in a vehicle. This includes vehicle designs that influence the presence of environmental and HVAC noise, microphone placement strategy, seat position, and cabin material and geometry. Interactions can be analyzed between these factors and dominant influencers identified. Relationships can then be established between ASR engine performance and attribute performance metrics that quantify the link between the two. This helps aid proper target setting and hardware selection to meet the customer satisfaction goals for both teams. |
A Tailgate(Trunk) Control System Based on Acoustic Patterns | When customers use a tailgate (or trunk), some systems such as power tailgate and smart tailgate have been introduced and implemented for improving convenience. However, they still have some problems in some use cases. Some people have to search for the outside button to open the tailgate, or they should take out the key and push a button. In some cases, they should move their leg or wait a few seconds which makes some people feel that it is a long time. In addition, they have to push the small button which is located on the inner trim in order to close the tailgate. This paper proposes a new tailgate control technology and systems based on acoustic patterns in order to solve some inconvenience. An acoustic user interaction (AUI) is a technology which responds to human?셲 rubbing and tapping on a specific part analyzing the acoustic patterns. The AUI has been recently spotlighted in the automotive industry as well as home appliances, mobile devices, musical instruments, etc. The AUI is a technology that can extend to rich-touch beyond multi-touch. The AUI can be easily applied and adapted even to the systems which need a large touch recognition area or have complex shape and surface. This paper addresses how to recognize the users??intention and how to control the tailgate using acoustic sensors and patterns. If someone who has the smart key wants to open the tailgate, he or she only needs to knock on the outer panel of the tailgate twice. When they want to close the tailgate, just touching anywhere of the inner trim of the tailgate will do. Various digital filters and algorithms are used for acoustic signal processing, and the effectiveness of the proposed methods is shown by a real tailgate system with a micro control unit. Finally, we suggest other applications of vehicles which use AUI technology. |
A CFD Analysis Method for Prediction of Vehicle Exterior Wind Noise | High frequency wind noise caused by turbulent flow around the front pillars of a vehicle is an important factor for customer perception of ride comfort. In order to reduce undesirable interior wind noise during vehicle development process, a calculation and visualization method for exterior wind noise with an acceptable computational cost and adequate accuracy is required. In this paper an index for prediction of the strength of exterior wind noise, referred to as Exterior Noise Power (ENP), is developed based on an assumption that the acoustic power of exterior wind noise can be approximated by the far field acoustic power radiated from vehicle surface. Using the well-known Curle?셲 equation, ENP can be represented as a surface integral of an acoustic intensity distribution, referred to as Exterior Noise Power Distribution (ENPD). ENPD is estimated from turbulent surface pressure fluctuation and mean convective velocity in the vicinity of the vehicle surface. Therefore calculations and visualizations of ENP and ENPD can be implemented in an unsteady Computation Fluid Dynamics (CFD) simulation without extra cost for acoustical computation. Applications of ENP and ENPD in vehicle development process can provide not only quantitative information about the acoustic power of exterior wind noise in parts of vehicle but also an indication of the location of dominant sources of exterior wind noise as well as the associated turbulent flows. The information of ENP and ENPD are helpful in order to set targets for exterior wind noise around each part of vehicle and to establish countermeasure designs for reduction of exterior wind noise. |
Reanalysis of Linear Dynamic Systems using Modified Combined Approximations with Frequency Shifts | Weight reduction is very important in automotive design because of stringent demand on fuel economy. Structural optimization of dynamic systems using finite element (FE) analysis plays an important role in reducing weight while simultaneously delivering a product that meets all functional requirements for durability, crash and NVH. With advancing computer technology, the demand for solving large FE models has grown. Optimization is however costly due to repeated full-order analyses. Reanalysis methods can be used in structural vibrations to reduce the analysis cost from repeated eigenvalue analyses for both deterministic and probabilistic problems. Several reanalysis techniques have been introduced over the years including Parametric Reduced Order Modeling (PROM), Combined Approximations (CA) and the Epsilon algorithm, among others. It has been shown that the Modified Combined Approximations (MCA) method - an improvement over CA - is the most efficient reanalysis technique for problems with a large number of degrees of freedom. This paper proposes an improvement of the MCA method using frequency shifts. Numerical examples are presented and results are compared with existing methods. |
Comparative Study of Adaptive Algorithms for Vehicle Powertrain Noise Control | Active noise control systems have been gaining popularity in the last couple of decades, due to the deficiencies in passive noise abatement techniques. In the future, a novel combination of passive and active noise control techniques may be applied more widely, to better control the interior sound quality of vehicles. In order to maximize the effectiveness of this combined approach, smarter algorithms will be needed for active noise control systems. These algorithms will have to be computationally efficient, with high stability and convergence rates. This will be necessary in order to accurately predict and control the interior noise response of a vehicle. In this study, a critical review of the filtered-x least mean square (FXLMS) algorithm and several other newly proposed algorithms for the active control of vehicle powertrain noise, is performed. The analysis examines the salient features of each algorithm, and compares their system performance. Numerical simulations utilizing synthesized data, are conducted to study the convergence rates of these algorithms. These convergence rates are critical for the noise control outcome. Furthermore, measured powertrain noise response is employed, to verify the system?셲 performance under more realistic conditions. The individual engine orders are targeted for attenuation or enhancement, to achieve the desired vehicle interior sound quality. |
Frontloading Approach for Sound Package Design for Noise Reduction and Weight Optimization Using Statistical Energy Analysis | First time right vehicle performance and time to market, remains all automotive OEMs top priority, to remain competitive. NVH performance of product communicates impression to customer, remains one of the most important and complex attribute to meet, considering performances to be met for 20 Hz -6000 Hz. Frontloading techniques (FEM/BEM/SEA/MBD) for NVH are critical and necessary to achieve first time right NVH performance. Objective of this paper is to present a frontloading approach for automotive sound package optimization (absorber, barrier and damper elements) for SUV vehicle. Current process of designing sound package is mainly based on experience, competitive benchmarking of predecessor products. This process (current process) heavily depend on testing and validation at physical prototype and happens at later stages of program, especially on tooled up body. This is because, structure borne noise development, sealing and leakage path treatment refinement assume priority over sound package development. This way of working has impacted on validation timelines, late changes in peripheral system, leading to cost increase and time delays. High frequency simulations (using statistical energy analysis) provides opportunity in terms of being able to evaluate design options and frontload sound package design in parallel with structure borne NVH development. In this exercise, SEA (statistical energy analysis) was used to predict full vehicle cabin noise (400 Hz-6000 Hz) by modelling all major paths (structure borne and air borne) present in vehicle. All major sources of excitation such as powertrain vibrations, suspension vibrations and engine bay noise, tyre patch noise, exhaust noise were used to predict cabin noise. Static and dynamic load cases were used to validate modelling confidence and model updating. Contribution analysis was used to identify dominant sources, transfer paths for optimization of sound package for performance and weight. |
Uncertainty Analysis of High-Frequency Noise in Battery Electric Vehicle Based on Interval Model | The high-frequency noise issue is one of the most significant noise, vibration, and harshness problems, particularly in battery electric vehicles (BEVs). The sound package treatment is one of the most important approaches toward solving this problem. Owing to the limitations imposed by manufacturing error, assembly error, and the operating conditions, there is often a big difference between the actual values and the design values of the sound package components. Therefore, the sound package parameters include greater uncertainties. In this article, an uncertainty analysis method for BEV interior noise was developed based on an interval model to investigate the effect of sound package uncertainty on the interior noise of a BEV. An interval perturbation method was formulated to compute the uncertainty of the BEV?셲 interior noise. The sound absorption coefficient and transmission loss of the sound package were obtained through tests, and a statistical energy analysis model of the BEV was established. The acoustic loads of the BEV were tested and the interior noise of the cabin was analyzed under certain working conditions. Uncertain parameters were introduced to describe the sound package system of the firewall. The sensitivities of the uncertain parameters were analyzed using the numerical sensitivity analysis method. The effect of interior noise was predicted through the interval perturbation method, and the robustness of the system was analyzed under the influence of uncertain parameters. |
Road Noise Evaluation by Sound Quality Simulation Module | An objective evaluation of sound quality is a technical bridge connecting sound pressure level (SPL) and human auditory sensation. In this paper, an algorithm is proposed for calculating objective evaluation parameters of sound quality (including loudness, sharpness and articulation index), considering acoustic characteristics of human external ear, middle ear and inner ear to reflect auditory sensation. A sound quality simulation (SQS) module is coded according to the algorithm. The module is used for evaluating sound quality of road noise from an SUV in three steps. Firstly, interior noise is predicted by integrating finite-element method (FEM), hybrid FE-SEA method, and statistical energy analysis (SEA) for low frequency (20~315 Hz), medium frequency (315~500 Hz), and high frequency (>500 Hz) in 1/3 octave band, respectively. The predicted interior noise SPLs are compared with the measured results, with deviations less than 3dB in average. Secondly, the sound quality parameters are calculated using the predicted SPLs in the SQS module. The predicted and measured loudness, sharpness, and articulation index are compared, with average deviations less than 5%. Finally, the predicted interior noise is filtered by the SQS module in 1/3 octave band, to determine the dominant contribution bands for the sound quality parameters. Several optimized designs are implemented to optimize the sound quality parameters, and validated by experiments. |
Windshield Glare from Bus Interiors: Potential Impact on City Transit Drivers at Night | Windshield glare at night is a safety concern for all drivers. Public transit bus drivers also face another concern about glare caused by interior lighting sources originally designed for passenger safety. The extent to which interior light reflections contribute to glare is unknown. Unique methods for measuring discomfort and disability glare during bus driving were developed. An initial simulation study measured windshield luminance inside of a New Flyer D40LF diesel bus parked in a controlled, artificial, totally darkened test environment. Findings indicated significant disability glare (from elevated luminance) in the drivers??primary field of view due to interior reflections. Any reduction in contrast would result in less prominent glare if actual driving conditions differ. To assess this, levels of windshield glare were also measured with the bus parked on the roadside under the ?쐀ackground glow??of the urban environment. Findings reveal that under road conditions the extent of disability glare from interior reflections is much less, but not negligible, when contrast is reduced. The information gathered in these studies may be useful to manufacturers and transit authorities to improve conditions for drivers and the travelling public. Measurement methods developed in this study may prove useful for assessing elements of interior design. The difference between disability and discomfort glare is discussed. The results provide directions for implementation of glare control strategies. |
Lockheed Martin Low-Speed Wind Tunnel Acoustic Upgrade | The Lockheed Martin Low-Speed Wind Tunnel (LSWT) is a closed-return wind tunnel with two solid-wall test sections. This facility originally entered into service in 1967 for aerodynamic research of aircraft in low-speed and vertical/short take-off and landing (V/STOL) flight. Since this time, the client base has evolved to include a significant level of automotive aerodynamic testing, and the needs of the automotive clientele have progressed to include acoustic testing capability. The LSWT was therefore acoustically upgraded in 2016 to reduce background noise levels and to minimize acoustic reflections within the low-speed test section (LSTS). The acoustic upgrade involved detailed analysis, design, specification, and installation of acoustically treated wall surfaces and turning vanes in the circuit as well as low self-noise acoustic wall and ceiling treatment in the solid-wall LSTS. The preservation of the aerodynamic flow quality and the reduction in background noise levels in the LSTS were demonstrated by a series of measurements that were performed both prior to and after the acoustic upgrade. |
Advancement in Vehicle Development Using the Auto Transfer Path Analysis | This paper presents the most recent advancement in the vehicle development process using the one-step or auto Transfer Path Analysis (TPA) in conjunction with the superelement, component mode synthesis, and automated multi-level substructuring techniques. The goal is to identify the possible ways of energy transfer from the various sources of excitation through numerous interfaces to given target locations. The full vehicle model, consists of superelements, has been validated with the detailed system model for all loadcases. The forces/loads can be from rotating components, powertrain, transfer case, chain drives, pumps, prop-shaft, differential, tire-wheel unbalance, road input, etc., and the receiver can be at driver/passenger ears, steering column/wheel, seats, etc. The traditional TPA involves two solver runs, and can be fairly complex to setup in order to ensure that the results from the two runs are consistent with subcases properly labeled as input to the TPA utility. However, auto TPA allows necessary data needed for the TPA analysis to be requested in a single frequency response analysis run. The TPA breaks down the total response to partial contributions from interface points under operation loads. Partial contributions to total response are then computed by multiplying transfer function with the force transmitted through each interface location. By comparing the results of two-step TPA with auto TPA, the effectiveness and efficiency of the auto TPA have been demonstrated for three load cases: a) powertrain excitation for cruising acceleration to engine torque (A/T) and noise to engine torque (P/T), b) propshaft imbalance, and c) rough road excitation, which is based on the power spectral density (PSD) function. |
Development of Feedback-Based Active Road Noise Control Technology for Noise in Multiple Narrow-Frequency Bands and Integration with Booming Noise Active Noise Control System | When a vehicle is in motion, noise is generated in the cabin that is composed of noise in multiple narrow-frequency bands and caused by input from the road surface. This type of noise is termed low-frequency-band road noise, and its reduction is sought in order to increase occupant comfort. The research discussed in this paper used feedback control technology as the basis for the development of an active noise control technology able to simultaneously reduce noise in multiple narrow-frequency bands. Methods of connecting multiple single-frequency adaptive notch filters, a type of adaptive filter, were investigated. Based on the results, a method of connecting multiple filters that would mitigate mutual interference caused by different controller transmission characteristics was proposed. This method made it possible to implement controllers with amplitude and phase characteristics in multiple narrow-frequency bands corresponding to design values, and to achieve the target noise-reduction. Additionally, in feedback-based road noise control, the amplitude of the control output signal changes drastically depending on the frequency characteristics of the road surface. When this technology was integrated with the already-commercialized booming noise control system, a method to adjust the range of each controller output automatically was applied, achieving integration while balancing noise reduction performance under normal conditions with control stability when the vehicle passes over a large-input surface. |
Source-Path-Contribution Methodologies across a Wide Range of Product Types | Source-path-contribution (SPC) analysis, or transfer-path-analysis, is a test based method to characterize noise and vibration contributions of a complex system. The methodology allows for the user to gain insight into the structural forces and acoustic source strengths that are exciting a system, along with the effects of the structural and acoustic paths between each source and a receiver position. This information can be utilized to understand which sources and/or paths are dominating the noise and vibration performance of a system, allowing for focused target cascading and streamlined troubleshooting efforts. The SPC process is widely used for automotive applications, but is also applicable for a wide range of product types. For each unique application the basic SPC principles remain constant, however best practices can vary for both measurement and analysis depending on the type of system being evaluated. In this paper the application of the SPC process is described across a range of different applications including automotive, agricultural, small engine, and smaller component-level applications. |
Current Status and Future Developments of ANC Systems | Active Noise Control (ANC) has long been seen as emerging technology. During recent years, however, it became popular in new vehicle and infotainment platforms within a broad range of OEMs. This paper summarizes the current status and lessons learned of production systems (as well as those entering production soon) and gives an outlook on how ANC and related technologies will integrate in future vehicles and audio/infotainment architectures. |
Coupling CFD with Vibroacoustic FE Models for Vehicle Interior Low-Frequency Wind Noise Prediction | With the reduction of engine and road noise, wind has become an important source of interior noise when cruising at highway speed. The challenges of weight reduction, performance improvement and reduced development time call for stronger support of the development process by numerical methods. Computational Fluid Dynamics (CFD) and finite element (FE) vibroacoustic computations have reached a level of maturity that makes it possible and meaningful to combine these methods for wind noise prediction. This paper presents a method used for coupling time domain CFD computations with a finite element vibroacoustic model of a vehicle for the prediction of low-frequency wind noise below 500 Hz. The procedure is based on time segmentation of the excitation load and transformation into the frequency domain for the vibroacoustic computations. It requires simple signal processing and preserves the random character as well as the spatial correlation of the excitation signal. The aeroacoustic load is applied on the entire outer surface of the vehicle body. The computed results are validated against wind tunnel measurements on a production vehicle. The numerical and experimental investigations provide some insight into the mechanisms involved in underbody wind noise. |
Sideglass Turbulence and Wind Noise Sources Measured with a High Resolution Surface Pressure Array | The authors report on the design and application of a high resolution micro-electro-mechanical (MEMS) microphone array for automotive wind noise engineering. The array integrates both sensors and random access memory (RAM) chips on a flexible circuit board that eliminates high channel count wiring and allows the array to be deployed on automobile surfaces in a convenient ?쐓tick-on/peel-off??configuration. These arrays have potential application to the quantitative evaluation of interior wind noise from measurements on a clay model in the wind tunnel, when used in conjunction with a body vibro-acoustic model. The array also provides a high resolution turbulence measurement tool, suitable for validation of computation fluid dynamics (CFD) simulations for wind noise. The authors' report on the wavenumber-frequency structure of flow turbulence measured in different flow regions on a side glass and the corresponding contributions to interior wind noise. |
Prediction of Interior Noise in a Sedan Due to Exterior Flow | Aero-vibro-acoustic prediction of interior noise associated with exterior flow requires accurate predictions of both fluctuating surface pressures across the exterior of a vehicle and efficient models of the vibro-acoustic transmission of these surface pressures to the interior of a vehicle. The simulation strategy used in this paper combines both CFD and vibro-acoustic methods. An accurate excitation field (which accounts for both hydrodynamic and acoustic pressure fluctuations) is calculated with a hybrid CAA approach based on an incompressible unsteady flow field with an additional acoustic wave equation. To obtain the interior noise level at the driver's ears a vibro-acoustic model is used to calculate the response of the structure and interior cavities. The aero-vibro-acoustic simulation strategy is demonstrated for a Mercedes-Benz S-class and the predictions are compared to experimental wind tunnel measurements. |
Optimization of a Porous Ducted Air Induction System Using Taguchi's Parameter Design Method | Taguchi method is a technology to prevent quality problems at early stages of product development and product design. Parameter design method is an important part in Taguchi method which selects the best control factor level combination for the optimization of the robustness of product function against noise factors. The air induction system (AIS) provides clean air to the engine for combustion. The noise radiated from the inlet of the AIS can be of significant importance in reducing vehicle interior noise and tuning the interior sound quality. The porous duct has been introduced into the AIS to reduce the snorkel noise. It helps with both the system layout and isolation by reducing transmitted vibration. A CAE simulation procedure has been developed and validated to predict the snorkel noise of the porous ducted AIS. In this paper, Taguchi's parameter design method was utilized to optimize a porous duct design in an AIS to achieve the best snorkel noise performance. The virtual experiments based on an orthogonal array in the parameter design method were conducted by the developed simulation procedure and the optimized design was recommended. Furthermore, the parts based on the optimized design are manufactured and tested to verify if the intended performance and other high priority requirements for the AIS are met. It was concluded that a traditional CAE analysis enhanced with robustness technique is an efficient tool to optimize the AIS design in this case study. |
The Predictive Simulation of Exhaust Pipe Narrow-band Noise | A method of predictive simulation of flow-induced noise using computational fluid dynamics has been developed. The goal for the developed method was application in the vehicle development process, and the target of the research was therefore set as balancing the realization of a practical level of predictive accuracy and a practical computation time. In order to simulate flow-induced noise, it is necessary to compute detailed eddy flows and changes in the density of the air. In the research discussed in this paper, the occurrence or non-occurrence of flow-induced noise was predicted by conducting unsteady compressible flow calculation using large eddy simulation, a type of turbulence model. The target flow-induced noise for prediction was narrow-band noise, a type of noise in which sound increases in specific frequency ranges. Assuming the area of generation of flow-induced noise to be the exhaust pipe, including the complex shape of the muffler, predictive accuracy was verified under conditions that modeled measurements in steady-state flow test equipment. In order to reduce computation time while maintaining predictive accuracy, calculation methods were combined and computation times compared. This made it possible to reduce computation time by 61% against that in the initial stage of development of the method. In addition, a study utilizing multiple exhaust pipe shapes indicated that a correlation existed between the number of computation cells and computation time. The developed method has made it possible to predict the occurrence of narrow-band noise within a practical computation time. |
Automobile Wind Noise Speed Scaling Characteristics | Wind noise, an aeroacoustic phenomenon, is an important attribute that influences customer sensation of interior quietness in a moving vehicle. As a vehicle travels faster, occupants' sensation of wind noise becomes increasingly objectionable. The purpose of this work is to investigate the increase of wind noise level perceived by a driver in response to an increase in wind speed. Specifically, it explores how much the level of wind noise at the DOE (driver outboard ear) would vary in response to a change in wind speed based on the test data obtained in a wind tunnel from ten vehicles that belong to several different passenger vehicle segments. The first part of this work studies the change of the SPL (sound pressure level) in response to a change in wind speed U. It shows that the SPL(dBA) approximately scales to U5.7 at the DOE and to U6.3 in the far-field, which could be interpreted as the dominance of dipoles. The second part of this work looks into the scaling of loudness measured in Zwicker sones that represent the human auditory sensation of wind noise level. It shows that the human perception of the wind noise loudness scales to U1.7 approximately, which indicates that the wind noise loudness sensation is doubled when the vehicle speed incurs a 50% increase. |
Assessing the Aeroacoustic Response of a Vehicle to Transient Flow Conditions from the Perspective of a Vehicle Occupant | On-road, a vehicle experiences unsteady flow conditions due to turbulence in the natural wind, moving through the unsteady wakes of other road vehicles and travelling through the stationary wakes generated by roadside obstacles. Separated flow structures in the sideglass region of a vehicle are particularly sensitive to unsteadiness in the onset flow. These regions are also areas where strong aeroacoustic effects can exist, in a region close to the passengers of a vehicle. The resulting aeroacoustic response to unsteadiness can lead to fluctuations and modulation at frequencies that a passenger is particularly sensitive towards. Results presented by this paper combine on-road measurement campaigns using instrumented vehicles in a range of different wind environments and aeroacoustic wind tunnel tests. A new cabin noise simulation technique was developed to predict the time-varying wind noise in a vehicle using the cabin noise measured in the steady environment of the wind tunnel, and a record of the unsteady onset conditions on the road, considering each third-octave band individually. The simulated cabin noise predicted using this quasi-steady technique was compared against direct on-road cabin noise measurements recorded under the same flow conditions to assess the response of the vehicle to oncoming flow unsteadiness. The technique predicted the modulation of the wind noise under unsteady on-road conditions with good fidelity. This is because the cabin noise response to oncoming flow unsteadiness remained generally quasi-steady up to fluctuation frequencies of approximately 2 to 5 Hz, with fluctuations at higher scales having a progressively smaller impact, and because most of the onset flow fluctuation energy on the road occurs at frequencies below this threshold. The relative impact of the baseline level of cabin noise and the sensitivity of the cabin noise to changes in yaw angle were assessed in terms of occupant perception and this highlighted the importance of modulation. This can provide guidance when assessing the on-road wind noise performance of vehicle geometry modifications and of different vehicles. |
Planetary Airlock and Suitlock Requirements and Alternate Approaches | This study describes the operational requirements for planetary surface access and compares the performance of a hatch, airlock, suitlock, and suitport. The requirements for mitigating dust, performing EVA (ExtraVehicular Activity) by only part of the crew, and use on Mars as well as the Moon are strong reasons to prefer an airlock over a simple hatch, which would require depressurizing the habitat and sending all the crew on EVA. A requirement for minimum cost would favor the hatch above all. A suitlock provides better dust mitigation than an airlock, but at higher cost and complexity. A suitlock accommodating two crew meets requirements for buddy assistance and ability to help an incapacitated crewmember. Two suitlocks would provide redundant airlocks. A suitport, similar to a suitlock but having a suit-bulkhead pressure seal and no outer airlock door, provides dust mitigation and operational flexibility similar to the suitlock at lower cost, but increases risk and limits contingency response. A combined airlock/suitlock/suitport has the broadest capability and flexibility. |
The Study of Roller Hemming Process for Aluminum Alloy via Finite Element Analysis and Experimental Investigations | Recently the automotive industry faces many competitive challenges including weight and cost reduction to meet the needs for high fuel efficiency. Therefore, the use of light metals such as aluminum alloys has been increased to produce the body structure of light-weight vehicles. However, since the formability of aluminum alloy is not as good as that of steel, it needs a special attention to body manufacturer during their forming process. Roller hemming technology has been introduced as a new production technique which has several advantages in terms of cost and time saving for trial and error. Since hemming is the last forming process in stamping, it determines the external quality of automotive outer parts such as doors, hood and trunk-lid. In this study, the implicit finite element analysis of roller hemming process on the flat surface-straight edge panel was performed by using the commercial code ANSYS. This study shows the process of roller hemming simulation with Von Mises stress and effective strain results. In addition, experimental investigations have been done to compare the results between the simulation and experiment. |
A Modern Development Process to Bring Silence Into Interior Components | Comfort and well-being have always been connected with a flawless interior acoustic, free of any background noise or BSR, (buzz, squeak and rattle). BSR noises dominate the interior acoustic and represent one of the main sources for discomfort often causing considerable warranty costs. Traditionally BSR issues have been identified and rectified through extensive hardware testing, which by its nature intensifies toward the end of the car development process. In the following paper the integration of a virtual BSR validation technique in a modern development process by the use of appropriate CAE methods is presented. The goal is to shift, in compliance with the front loading concept, the development activities into the early phase. The approach is illustrated through the example of an instrument panel, from the early concept draft for single components to an assessment of the complete assembly. In a second and innovative example a combination of a virtual door slam analysis with a subsequent BSR analysis is examined. Every analysis result shown in the paper will be compared with corresponding test results. |
Obstacle Detection for Power Folding Seats | In the past years the automotive industry has equipped it's vehicles with more and more automated power driven functions. Starting with the ?쐃xpress up/down ??functions for power windows and ?쐃asy entry/exit??functions of memory seats, automated power movements have also been introduced into power sliding doors as well as power liftgates. In contrast to ?쐏ress & hold??switch activated movement, where the operator takes responsibility for the movement, the control unit of the ?쏿utomated??or ?쐎ne-touch??movement has to provide some sort of obstacle detection or pinch protection. This paper deals with the adaptation of a pinch protection algorithm for linear movements like power windows or memory seat applications to the rotational movement of power folding seats. With the considerable weight of a seat that is involved the motor torque changes along the travel of the seat, sometimes even reaching negative values in those positions where obstacles would most likely need to be detected. On the other hand, obstacle detection must be less sensitive in areas where the seat needs to be moved against gravity and where complex seat mechanics introduce non-linear torque requirements. The paper addresses these issues and describes basic functionality, such as how to obtain a voltage compensated torque equivalent signal from a hall sensor speed signal. It also describes the challenges that arise from rotational movement. |
Using Spherical Beamforming to Evaluate Wind Noise Paths | Microphone array based techniques have a growing range of applications in the vehicle development process. This paper evaluates the use of Spherical Beamforming (SB) to investigate the transmission of wind-generated noise into the passenger cabin, as one of the alternative ways to perform in-vehicle troubleshooting and design optimization. On track measurements at dominant wind noise conditions are taken with the spherical microphone array positioned at the front passenger head location. Experimental diligence and careful processing necessary to enable concise conclusions are briefly described. The application of Spherical Harmonics Angularly Resolved Pressure (SHARP) and the Filter-And-Sum (FAS) algorithms is compared. Data analysis variables, run-to-run repeatability and system capability to identify design modifications are studied. It is demonstrated that the Spherical Beamforming is a powerful tool to visualize dominant noise paths in vehicle, providing valuable information for the wind noise control at the transmission paths rather than using the standard single microphone operational data at the observer location. |
Study of Coupling Behavior of Acoustic Cavity Modes to Improve Booming Noise in Passenger Vehicles | Interior sound quality is one of the significant factors contributing to the comfort level of the occupants of a passenger car. One of the major reasons for the deterioration of interior sound quality is the booming noise. Booming noise is a low frequency (20Hz??00Hz) structure borne noise which occurs mainly due to the powertrain excitations or road excitations. Several methods have been developed over time to identify and troubleshoot the causes of booming noise [1]. In this paper an attempt has been made to understand the booming noise by analyzing structural (panels) and acoustic (cavity) modes. Both the structural modes and the acoustic modes of the vehicle cabin were measured experimentally on a B-segment hatchback vehicle using a novel approach and the coupled modes were identified. Panels contributing to booming noise were identified and countermeasures were taken to modify these panels to achieve decoupling of structural and cavity modes which results in the reduction of cabin noise levels. This is followed by countermeasure validation resulting into booming noise reduction. |
Multidisciplinary Design Optimization of BEV Body Structure | Blade Electric Vehicle (BEV) with a light body plays an important role in saving the energy and reducing the exhaust emission. However, reducing the body weight need to meet the heterogeneous attributes such as structural, safety and NVH (Noise, Vibration and Harshness) performance. With the rapid development of finite element (FE) analysis technology, simulation analysis is widely used for researching the complex engineering design problem. Multidisciplinary Design Optimization (MDO) of a BEV body is a challenging but meaningful task in the automotive lightweight. In present research, the MDO is introduced to optimize a BEV Body-in-White (BIW). The goal of optimization is to minimize the mass of the BIW while meeting the following requirements: structural performance (the bending and torsion stiffness is increased), NVH performance (the first overall torsion frequency is increased), and safety performance (the roof crush resistance is improved).The sample points were obtained by using Design of Experiment (DOE) with optimal Latin hypercube. The approximation models of mass, bending stiffness, torsion stiffness, modal and safety were established with the polynomial response surface method (RSM). The thicknesses of nine parts of the BIW were selected to be optimized by Muti-island Genetic Algorithm (MGA) method. After the MDO of the BIW, the paper drew the following conclusions: 1.The predictive values of the approximation and the results of FE simulation had a good agreement with an error less than 5.00% and the former met the engineering requirements; 2.The weight of the BIW was reduced by 2.00% and the optimized BIW met all prescribed requirements about structural, NVH and safety performance. |
Approach to Control the in Cab Noise without Affecting Passenger Comfort in AC Midi Buses | This paper discusses various fruitful iterations / experiments performed to reduce air flow induced noise without compromising on total air flow requirement for thermal comfort and ways to avoid heat ingress inside the bus. Also the paper discusses the devised process for noise reduction through front loading of computer aided engineering and computational fluid dynamics analysis. Air conditioning buses in light commercial vehicle (LCV) segment is growing market in India, especially for applications like staff pick-up and drop, school applications and private fleet owners. The air-conditioning system is typically mounted on bus roof top and located laterally and longitudinally at center. It is an easiest and most feasible way to package air conditioning system to cater the large passenger space (32 to 40 seats) with the conditioned air. This makes air conditioning duct design simple and commercially viable. Most of the LCV buses are with front engine configuration which adds more heat and noise to driver and passenger compartment, this demands for isolation of driver's area from passenger area by means of partition in between. In case of buses without partition engine noise is more dominant, but in case of buses with partition, blower noise of roof mounted AC system is more perceivable in passenger area. The larger glass area, limitation on glass tint percentage and mandate for not to use curtain added more challenges in front of thermal engineer to device effective cabin cooling system to cater huge heat load and achieve required human comfort. |
Development of Prediction Method for Dynamic Strain on Windshield during Passenger Airbag Deployment | The objective of this study is to accurately predict the dynamic strain on the windshield caused by the deployment of the airbag in a short term without vehicle tests. The following assumption is made as to the dynamic pressure distribution on the windshield: The deployment of the airbag is fast enough to ignore spatial difference in the patterns of the pressure time histories. Given this assumption, significant parameters of the dynamic pressure distribution are as follows: 1) the distribution of the maximum pressure during contact between the airbag and the windshield, and 2) the characteristic of the force time histories applied to the windshield by the deploying airbag. In this study, the prediction method consists of a simplified airbag deployment test and an FE simulation. The simple deployment test was conducted to measure the peak pressure distribution between the airbag and a flat panel simulating the windshield. The pressure time history curves were determined by scaling the force time histories from the load cells. The scale factor was identified for each of the measuring points on the pressure measurement film. Prescribed pressure time histories were directly applied to the part of the FE mesh specifically used to load the windshield. In order to validate the developed prediction method, the strain from the FE simulation was compared with that from strain gauges in the vehicle tests. The results showed that the predicted strain on the windshield caused by the airbag deployment correlated well with the data measured in the vehicle tests, suggesting that the prediction method developed in this study can be a valuable tool for improving the efficiency of development. |
Prediction of Structureborne Noise in a Fully Trimmed Vehicle Using Poroelastic Finite Elements Method (PEM) | Since the last decade, the automotive industry has expressed the need to better understand how the different trim parts interact together in a complete car up to 400 Hz for structureborne excitations. Classical FE methods in which the acoustic trim is represented as non-structural masses (NSM) and high damping or surface absorbers on the acoustic cavity can only be used at lower frequencies and do not provide insights into the interactions of the acoustic trims with the structure and the acoustic volume. It was demonstrated in several papers that modelling the acoustic components using the poroelastic finite element method (PEM) can yield accurate vibro-acoustic response such as transmission loss of a car component [1,2,3]. The increase of performance of today's computers and the further optimization of commercial simulation codes allow computations on full vehicle level [4,5,6] with adequate accuracy and computation times, which is essential for a car OEM. This paper presents a study of a fully trimmed vehicle excited by structureborne excitations with almost all acoustic trims such as seats, dash insulator, instrument panel, headliner??which are modelled as poroelastic finite element (PEM) parts. Simulation results are compared with extensive measurement results. The interactions between structure, acoustic trims and acoustic volume are illustrated and finally the analysis of several design changes such as trim material properties or geometry modifications is demonstrated. |
A Computational Aeroacoustic Study of Windshield Wiper Influence on Passenger Vehicle Greenhouse Windnoise | This paper presents an approach to numerically simulate greenhouse windnoise. The term ?쐅reenhouse windnoise??here describes the sound transferred to the interior through the glass panels of a series vehicle. Different panels, e.g. the windshield or sideglass, are contributing to the overall noise level. Attached parts as mirrors or wipers are affecting the flow around the vehicle and thus the pressure fluctuations which are acting as loads onto the panels. Especially the wiper influence and the effect of different wiper positions onto the windshield contribution is examined and set in context with the overall noise levels and other contributors. In addition, the effect of different flow yaw angles on the windnoise level in general and the wiper contributions in particular are demonstrated. As computational aeroacoustics requires accurate, highly resolved simulation of transient and compressible flow, a Lattice-Boltzmann approach is used. The noise transmission through the interior is then modeled by statistical energy analysis (SEA), representing the vehicle cabin and the panels excited by the flow. Results are verified by comparisons to windtunnel experiments. |
Attenuation of Aeroacoustic Noise of a Typical Van Using Passive Devices through CFD Simulation | The present numerical analysis aims at studying the effect of changes in profile of van on aero-acoustic noise and aerodynamic drag. The numerical analysis is carried out using commercial CFD software, ANSYS Fluent, with k-epsilon & Large Eddy Simulation turbulence models. In present study five models of truck are analysed, including baseline model at different Reynolds numbers, namely 0.391, 0.415 and 0.457 million. In order to reduce the aero-acoustic noise, various profile modifications have been adapted on existing van model by adding a top and bottom diffuser at the rear of the truck. The comparison has been done with respect to coefficient of drag, coefficient of pressure, pressure contours for all four cases. It is observed from the simulation results among different modifications of truck, adding a top and bottom diffuser of 15 degrees at the rear end of truck gives the maximum reduction in aero-acoustic noise up to 9.4% and aerodynamic drag reduction of 3.8 % as compared to baseline model, at a speed of 81 km/h. |
Performance Analysis on 3D Printed Beak-Shaped Automotive Tail Fin Filled with Honeycomb Cellular Structure | The concept of ?쐀ionic design??has driven the developments of automotive design. In this paper, a novel beak-shaped automotive tail fin with honeycomb cellular structure is proposed based on the idea of ?쐀ionic design?? Beak-shaped appearance is utilized to meet the requirement of aerodynamics performance, inner honeycomb cellular structure is filled to achieve more lightweight space. This paper starts from the establishment of three dimensional (3D) model based on the real characteristics of sparrow?셲 beak. On this basis, aerodynamic performances of novel beak-shaped tail fin and conventional shark tail fin are analyzed by experiment. Finally, the stiffness and modal analyses of solid beak-shaped tail fin and honeycomb beak-shaped tail fin are carried out respectively. The results indicate that the deformation of solid beak-shaped tail fin and honeycomb beak-shaped tail fin satisfy the basic requirements. In addition, the first order modal frequencies of solid and honeycomb beak-shaped tail fins are both far away from body vibration frequency and effectively avoid resonance. Compared with solid beak-shaped tail fin, the weight of honeycomb beak-shaped tail fin decreases by about 25%. Thus, the novel honeycomb beak-shaped tail fin proposed in this work demonstrates outstanding performance in terms of aerodynamic performances, structural stiffness enhancement and weight reduction. |
Automatic Speech Recognition System Considerations for the Autonomous Vehicle | As automakers begin to design the autonomous vehicle (AV) for the first time, they must reconsider customer interaction with the Automatic Speech Recognition (ASR) system carried over from the traditional vehicle. Within an AV, the voice-to-ASR system needs to be capable of serving a customer located in any seat of the car. These shifts in focus require changes to the microphone selection and placement to serve the entire vehicle. Further complicating the scenario are new sources of noise that are specific to the AV that enable autonomous operation. Hardware mounted on the roof that are used to support cameras and LIDAR sensors, and mechanisms meant to keep that hardware clean and functioning, add even further noise contamination that can pollute the voice interaction. In this paper, we discuss the ramifications of picking up the intended customer?셲 voice when they are no longer bound to the traditional front left ?쐂river?셲??seat. Considerations are made to the possibilities of new microphone construction and layouts to provide coverage for all potential passengers, and cost-efficient minimal microphone packages are discussed. Additionally, if the automaker chooses to initiate the ASR interaction with a ?쐗ake up word?? instead of installing Push to Talk (PTT) buttons for every seat, we discuss how the multiple microphone?셲 placements can be leveraged to identify the seat issuing the command, and focus further ASR interactions with that location in the car. |
A Non-Contact Technique for Vibration Measurement of Automotive Structures | The automotive and aerospace industries are increasingly using the light-weight material to improve the vehicle performance. However, using light-weight material can increase the airborne and structure-borne noise. A special attention needs to be paid in designing the structures and measuring their dynamics. Conventionally, the structure is excited using an impulse hammer or a mechanical shaker and the response is measured using uniaxial or multi-axial accelerometers to obtain the dynamics of the structure. However, using contact-based transducers can mass load the structure and provide data at a few discrete points. Hence, obtaining the true dynamics of the structure conventionally can be challenging. In the past few years, stereo-photogrammetry and three-dimensional digital image correlation have received special attention in collecting operating data for structural analysis. These non-contact optical techniques provide a wealth of distributed data over the entire structure. However, the stereo camera system is limited by its field of view of the cameras and can only measure the response on the parts of the structure that cameras have the line of sight. Therefore, a single pair of Digital Image Correlation (DIC) cameras may not be able to provide deformation data for the entire structure. In current work, a multi-view 3D DIC approach is used to predict the vibrational characteristics of a full vehicle. A pair of DIC cameras is roved over the entire vehicle to capture the deformation data of each field of view. The measured data includes the geometry and displacement data which is mapped into the global coordinate system using 3D transformation matrices. The obtained data in the time domain for each field of view is transformed to the frequency domain using the Fast Fourier Transformation (FFT) to extract the operational deflection shapes and resonant frequencies for each field of view. The obtained deflection shapes are scaled and stitched in the frequency domain to extract the operating deflection shapes of full vehicle. |
Extensive Correlation Study of Acoustic Trim Packages in Trimmed Body Modeling of an Automotive Vehicle | In the automotive sector, the structure borne noise generated by the engine and road-tire interactions is a major source of noise inside the passenger cavity. In order to increase the global acoustic comfort, predictive simulation models must be available in the design phase. The acoustic trims have a major impact on the noise level inside the car cavity. Although several publications for this kind of simulations can be found, an extensive correlation study with measurement is needed, in order to validate the modeling approaches. In this article, a detailed correlation study for a complete car is performed. The acoustic trim package of the measured car includes all acoustic trims, such as carpet, headliner, seats and firewall covers. The simulation methodology relies on the influence of the acoustic trim package on the car structure and acoustic cavities. The challenge lies in the definition of an efficient and accurate framework for acoustic trimmed bodies. Two different approaches to achieve this objective are reviewed. In the first approach, the acoustic trim package is modeled as a set of porous and solid layers represented by finite elements in physical coordinate system. The acoustic trim models update the modal fluid / structure model of the car body and car cavity. The second approach uses impedance surfaces to apply the acoustic absorption of the trim on the car cavity side. It uses a Virtual Kundt?셲 tube. Both approaches are solved as state of the art modal analysis. The result of the correlation study with measurements provides acceleration and Sound Pressure Level (SPL) results for different configurations and excitations, introducing the Root Mean Squared Deviation (RMSD). The expected difference between the two approaches is obtained. The first approach results in higher correlation accuracy than the second approach, while the second approach has advantages in computational time. |
Towards a Quiet Vehicle Cabin Through Digitalization of HVAC Systems and Subsystems Aeroacoustics Testing and Design | With the rise of electric autonomous vehicles, it has become clear that the cabin of tomorrow will drastically evolve to both improve ride experience and reduce energy consumption. In addition, autonomy will change the transportation paradigm, leading to a reinvention of the cabin seating layout which will offer the opportunity to climate systems team to design quiet and even more energy efficient systems. Consequently, Heat and Ventilation Air Conditioning (HVAC) systems designers have to deliver products which perform acoustically better than before, but often with less development time. To success under such constraints, designers need access to methods providing both assessment of the system (or subsystems) acoustic performance, and identification of where the designs need to be improved to reduce noise levels. Such methods are often needed before a physical prototype is requested, and thus can only be achieved in a timely manner through digital testing. Previous studies have demonstrated the ability of a CFD/CAA approach based on the Lattice Boltzmann Method (LBM) to predict HVAC system noise including real and complex ducts, registers, mixing unit and blower geometries. This LBM low dissipative numerical approach has indeed been shown to accurately capture turbulent and convective mechanisms and to propagate acoustic waves in ducted systems and in free-field. Combined with a noise source identification strategy, these methods provide the ability to visualize the noise sources inside the system, as well as to identify and rank noise-generating design features - a unique design methodology not available with physical testing. In this paper, such an approach is presented based on two HVAC systems layout, targeting two different vehicles. To answer the need for systems and subsystems predictions, simulation results are correlated to experiment for configurations with blower alone, blower + air intake, and for full HVAC system (blower + air intake + mixing unit). Finally, an in-depth analysis of the flow noise sources contributions to a microphone location is performed, and countermeasures are discussed. |
New ?쁁ottlebrush??Electroactive Polymers Make Dielectric Elastomers Increasingly Viable for Use in Devices | A multi-institutional research team has developed a new electroactive polymer material that can change shape and size when exposed to a relatively small electric field. The advance overcomes two longstanding challenges regarding the use of electroactive polymers to develop new devices, opening the door to a suite of applications ranging from microrobotics to designer haptic, optic, microfluidic, and wearable technologies. The work was performed by researchers at North Carolina State University, the University of North Carolina at Chapel Hill, Carnegie Mellon University, and the University of Akron. |
2021 Ford Bronco aims to kick some Jeep | ?쏷here is nothing on this truck that is superfluous - no decorative chrome or extraneous styling. It's designed for function, not fashion,??explained Paul Wraith, chief designer for Ford's much-anticipated 2021 Bronco. ?쏶uper-short overhangs for aggressive approach, departure and breakover angles. Slim ?쁥ips??for off-road agility. Everything is exactly where you need it. Getting that stuff right is harder than you think,??he admitted. To create the much-anticipated U725 (as the new 2- and 4-door Bronco is known internally and by suppliers), Wraith and his team decided to veer outside of Ford's traditional product-development process. It was the only way to execute the program's broad scope and unique requirements. ?쏛s we developed the truck, we invented a new human-centered methodology,??Wraith told media ahead of Bronco's July 13 unveiling. ?쏻e made low-fidelity models out of foam-core packing materials which drove our [prototype] shops crazy,??he said. ?쏛nd we ended up skipping a whole bunch of typical studio processes. This stirred things up quite a bit.??
Getting driverless trucks onto roadways,Autonomous developers at TuSimple address many technical issues |
Trucking Without Truckers | The challenges are myriad, but automated-trucking developer TUSimple believes the efficiencies of true depot-to-depot driverless hauling are too promising to ignore. The developers who are creating autonomous systems have plenty of complex technical questions that must be analyzed and solved, but their challenges don't stop there. Design teams also have to plan for the use cases of driverless vehicles, even going so far as to plan for what might happen if the vehicle has to sacrifice itself to avoid a serious accident. The challenges associated with the sea change wrought by autonomous trucking has opened the door for companies such as TuSimple, a Chinese startup that's partially funded by Nvidia. The company is developing digital control systems, focusing on both the prototypes needed to prove the safety of driverless trucks as well as the many issues associated with getting them into day-to-day operations. |
Steel stands TALL | Mobility's longtime incumbent material maintains its star status for vehicle structures through constant innovation-and a collaborative development model. In 2014, just before Ford shook the industry with the introduction of its aluminum-intensive F-150, Ducker Worldwide released a study for the aluminum industry. The report predicted that the light metal would dominate the North American light-truck segment in the next new-model development cycle. Some seven out of ten pickups in the next round were going to be AL-intensive, the study opined. A tidal wave appeared to be building. Five years later, not a single pickup has entered production with an AL-intensive cab and bed. While Ford changed over the body structures of its all-new 2018 large SUVs to aluminum, steel rules the midsized 2019 Ranger. In the enemy camps, the 2019 Chevrolet and GMC Silverado and Sierra 1500 and their brawnier HD cousins continue GM's mixed-materials strategy for pickups and SUVs. FCA's Ram and Jeep brands have stuck mainly with steel structures; the new JL-series Jeep Wrangler changed to aluminum doors (and hinges), hood, fenders and windshield frame, utilizing Alcoa's new C6A1 high-form alloy and its 6022 and A951 alloys. |
Thermal Technology System Acquires Heat Data to Count People | The Flowslide, developed by Royal Boon Edam Group Holding BV, is a combination of a revolving door and curved sliding panels, installed at Charles de Gaulle Airport, Paris. The Flowslide offers a complete physical separation between two crossing passenger flows on a single floor, allowing arriving and departing passengers to use a single door. The entry and exit points open and close alternatively within the curved wall of the revolving door, while keeping the passengers separate. As the two sets of passengers never come into contact with each other ??despite using the same doorway ??the Flowslide has enabled today's higher levels of security to be met, without the need to redevelop the terminal. |
Fabrication of Lightweight Armored Doors for HMMWVs | A document describes a concept for fabricating lightweight armored doors for the Army?셲 high-mobility multipurpose wheeled vehicles (HMMWVs). Essentially, the concept is to reinforce high-hard (HH) steel armored doors used on some HMMWVs with a laminated, woven, high-tensile-strength glassfiber/ polyester-matrix composite that has performed well as armor material in previous military applications. A fabrication procedure for implementing the concept, described in the document, can be summarized as follows: |
RoboSimian Software System from the DARPA Robotics Challenge Finals | A software architecture to allow semi-autonomous mobile manipulation of highly dexterous robots under degraded communications was developed to enable remote operation of a mobile manipulation robot as a first responder in a disaster-response scenario. The software architecture is structured to be adaptable at the lowest level and repeatable at the highest level. This architecture strikes the right balance between autonomy and supervision, and lets the robot excel in its capabilities (repeatability, strength, precision) and lets the operators excel at their capabilities (situational awareness, context, high-level reasoning). |
Airborne Hyperspectral Imaging System | A document discusses a hyperspectral imaging instrument package designed to be carried aboard a helicopter. It was developed to map the depths of Greenland?셲 supraglacial lakes. The instrument is capable of telescoping to twice its original length, allowing it to be retracted with the door closed during takeoff and landing, and manually extended in mid-flight. While extended, the instrument platform provides the attached hyperspectral imager a nadircentered and unobstructed view of the ground. |
Driving the CAR toward 54.5 mpg | Chances are good that if you're involved with automotive manufacturing strategy, you know Jay Baron. As President and CEO of the Center for Automotive Research (CAR) in Ann Arbor, Dr. Baron and his research teams are engaged with technology issues across a broad front, but even a brief conversation with him reveals his deep passion for plants, advanced processes and materials. Get him talking about lightweighting and he won't stop. The following exchange was taken from our July 2016 interview. At what point does the rising cost of vehicle compliance allow the over-the-horizon lightweighting technologies to enter production? |
Racing toward autonomous future, Cadillac and Mercedes-Benz reveal sultry, drive-it-yourself concept cars | In the autonomous-vehicle future, will the ultimate luxury become driving for yourself? That appears to be the suggestion from General Motors' Cadillac premium-car unit and Germany's Mercedes-Benz-both unveiled lusciously-proportioned concept cars at August's Monterey Car Week, where executives for both companies took pains to say the vehicles would be best enjoyed if, well, you actually drove them. |
Concurrent Development Environment Combining Mechanical and Control Systems for PBD and PSD | Due to advancements in multi-body dynamic analysis methodologies, virtual prototyping has been extended into various fields. Those methods can be applied to confirm behavior of the mechanical systems, to determine the necessary driving forces, and to predict the loads for each component of the system. Further, those methods combined with the control system have been applied to the controller tuning. Virtual evaluation environments have been developed, including the multi-body dynamic analysis, and have been applied to a power back door system (PBD) and a power sliding door system (PSD). As a result, development costs and timing have been reduced due to the utilization of these new evaluation methods. |
Simulation of Hot Stamping Process With Advanced Material Modeling | Advanced material modeling was conducted to describe the thermal-mechanical behavior of Boron Steel during hot stamping, a process in which blanks at 900 째C are formed and quenched between cold dies. Plastic deformation, thermal dilatation and phase transformation were incorporated in the constitutive model and a user-defined subroutine was developed to interface with LS-DYNA. Simulation was conducted on the hot stamping process of a door intrusion beam to gain insight into the physics of the process. Results showed significant influence of the thermal cycle on final product. It was also demonstrated that the program developed can be used as an early feasibility tool to determine baseline processing parameters and to detect potential defects in products without physical prototyping. |
Honeywell's Automotive Door Latch Design is Ideal for Corporate Latch Strategy | In response to consumer demand, automakers are adding more safety, security, and convenience features to vehicle access control systems. Also, in a continuing effort to be more profitable, automakers are reducing costs by outsourcing the design of systems/sub-systems/components, reducing their supply base, and minimizing part numbers by sharing components across several platforms. In an attempt to improve efficiency and productivity, many OEM's have adopted a ?쐁orporate latch??strategy, implementing the same latch across several manufacturing platforms and marketing divisions. Honeywell's revolutionary door latch design efficiently and cost effectively addresses vehicle OEMs' current and future requirements for performance and functionality. Utilizing this modular latch design allows OEMs to maximize design re-use, minimize tooling and development costs, hasten time to market, reduce program risk by utilizing pre-proven/validated designs and allows for upgrades in functionality through transparent design modifications that appear seamless within the application. Honeywell's Universal Latch provides all levels of functionality within the same packaging envelope and is the perfect enabler for a ?쐁orporate latch??strategy. Features and functions offered by the latch include: Central Locking Super Locking Selective Locking Electric Child Safety Power Door Releasing (Unlatching) Power Door Closing (Cinching) Most impressive is the fact that Honeywell's latch provides all of these features and functions with one small motor! Currently, competitive latch designs require the utilization of as many as three distinct motors to offer the same capabilities. This paper will present characterization data for the Universal Latch and compare its performance to competitive latches currently on vehicles. Furthermore, a feature value analysis will be provided to illustrate the benefits and savings the Honeywell design can provide to the entire access control system. After considering all of the facts presented in the paper, the reader will easily conclude that Honeywell's automotive door latch is smaller, lighter, quieter, faster, safer, and more cost effective than any automotive door latching/locking system on the market today. |
Validation of Non-linear Load-Controlled CAE Analyses of Oil-Canning Tests of Hood and Door Assemblies | Two finite element methodologies for simulating oil-canning tests on closure assemblies are presented. Reflecting the experimental conditions, the simulation methodologies assume load-controlled situations. One methodology uses an implicit finite-element code, namely ABAQUS짰, and the other uses an explicit code, LS-DYNA짰. It is shown that load-displacement behavior predicted by both the implicit and explicit codes agree well with experimental observations of oil-canning in a hood assembly. The small residual dent depth predictions are in line with experimental observations. The method using the implicit code, however, yields lower residual dent depth than that using the explicit code. Because the absolute values of the residual dent depths are small in the cases examined, more work is needed, using examples involving larger residual dent depth, to clearly distinguish between the two procedures. The analysis performed using the implicit code was significant more efficient (in terms of CPU hours) than the analysis done using the explicit code. The effects of forming strains are qualitatively examined. Forming induced thickness changes and plastic strains may not have a significant effect on oil-canning behavior, but may influence the residual dent depth strongly. Further reinforcement of the predictability of the methodology is demonstrated by an oil-canning simulation, using the implicit code, of a door assembly. |
Reliability Analysis of Systems with Nonlinear Limit States; Application to Automotive Door Closing Effort | In this paper, an efficient method for the reliability analysis of systems with nonlinear limit states is described. It combines optimization-based and simulation-based approaches and is particularly applicable for problems with highly nonlinear and implicit limit state functions, which are difficult to solve by conventional reliability methods. The proposed method consists of two major parts. In the first part, an optimization-based method is used to search for the most probable point (MPP) on the limit state. This is achieved by using adaptive response surface approximations. In the second part, a multi-modal adaptive importance sampling method is proposed using the MPP information from the first part as the starting point. The proposed method is applied to the reliability estimation of a vehicle body-door subsystem with respect to one of the important quality issues -- the door closing effort. The superiority of the proposed method, in terms of efficiency and accuracy, is demonstrated with a numerical example of highly nonlinear limit state problem, as well as an automotive door closing effort application. A generalized framework for reliability estimation is also proposed for problems with large numbers of random variables and complicated limit states. |
An Acoustical Imaging Processing for the Localization of Acoustic Sources inside a Vehicle: Method and Results for Tests on Road | The localization of acoustic sources inside a moving vehicle presents at least two main difficulties. The zone to be explored may be important (such as a door, a window, the toe board): the use of a sound intensity probe may take an expensive time for the context of a moving car. The other difficulty is the presence of a background noise, increasing with the car speed. These two difficulties may be overcome by the use of a robust acoustical imaging method, but the utilization of the system requires a few precautions for the implementation and for the interpretation of the acoustic images. The purpose of this paper is to present the chosen acoustical imaging processing, based on the beamforming method, and the procedure for the set-up and tests. This processing and the procedure are applied for experimental tests on the road and for different configurations: constant and decelerating speed. Acoustic images are presented for the case of sources on a passenger door. To improve the interpretation of the results, acoustic images are obtained for different tape configurations. This study shows a good robustness of the system and reliable results. In addition, the use of beamforming processing allows a reduced time for the set-up and for the measurements. |
Update on the Pininfarina ?쏷urbulence Generation System??and its effects on the Car Aerodynamics and Aeroacoustics | The Turbulence Generation System designed and built in Pininfarina in the years 1999-2002, has been in operation since the beginning of 2003. The purpose of this device is to reproduce in the wind tunnel a flow condition more similar to that found by the cars on the road, in terms of velocity profile and turbulence intensity/length scale. The paper reports an updated description of its mechanical and aerodynamic characteristics. Then it reports examples of results measured on some cars, in the condition of turbulent flow, regarding: Aerodynamics - time averaged and time-dependent aero coefficients. Aeroacoustics - auto spectra and psycho acoustic parameters. Deformation/vibration of some car body parts (bonnet, doors). The differences between these results and those measured in standard low-turbulence conditions are presented. In addition a description of some techniques that are used for these time-dependent measurements is reported. |
Robust Design of Glass Run-Channel Seal | Glass run-channel seals are located between DIW (Door in White) and window glass. They are designed to allow window glass to move smoothly while other two major requirements are met; (1) Provide insulation to water leakage and noise, and (2) Stabilize the window glass during glass movement, door slamming and vehicle operation. For a robust glass guidance system, it is critical to minimize the variation of seal compression force. In addition, it is desired to maintain a low seal compression force, which meets the minimum requirement for insulating water leakage/noise and stabilizing the window glass, for enhancing the durability of glass guidance system. In this paper, a robust synthesis and design concepts on the glass run-channel seal is presented. The developed concept is demonstrated with test data. |
Ballistic Armoring of Passenger Cars on the Assembly Line Adds Quality and Passengers Comfort by Using Advanced and Light Weight Composite Materials | Light weight composite materials were developed to provide ballistic protection to automobiles against handgun bullets and to increase passengers comfort by the elimination of UV radiation and reduction of infra-red solar energy and interior noise, without compromising the driving performance of the car. Structural designs were incorporated to be able to armor the car on the assembly line with the added benefits of turn-over time, cost reduction and quality of the finished assembly. Weight reduction of armor materials have been achieved with CrystalGard짰 and YellowGard짰. For windows and windshield, CrystalGard짰 17mm provides better ballistic protection against NIJ Level IIIA with a 27% weight reduction than the standard 21mm glass solution by using a double layer of polycarbonate. SolarBlock짰 eliminates the UV radiation and reduces 95% of the infra-red solar energy for added passengers comfort. For the ceiling, doors, dashboard and trunk, YellowGard짰 provides more than 80% weight reduction when compared with steel and reduces interior noise. YellowGard짰 is a thermo-formable Kevlar짰 fabric coated with a thermoplastic resin developed for ease of installation during assembly, resistance to high temperature and humidity, and reduced delamination upon multiple bullet hits. Advantages of online assembly of ballistic protection include the reinforcement of the door latch and column areas for durability, the adjustment of the suspension system to the original driving performance changed due to the extra weight, and the installation of the Kevlar짰 panels to the frame and doors during the assembly of the car to avoid cutting and welding the frame structure. |
Swing Gate Development and Correlation Studies | This paper documents the Engineering design of the rear door system for Ford's South American New Vehicle. This Closure system represents a first for the Engineering Department of Ford branded products and it also offers many industry firsts for the customer. This paper is not a concise A-Z document on Closure design, but a detailed report listing the important factors to consider in a Swing Gate. |
A Low Cost, Lightweight Solution for Soft Seamless Airbag Systems | OEM and Tier One integrated suppliers are in constant search of cockpit system components that reduce the overall number of breaks across smooth surfaces. Traditionally, soft instrument panels with seamless airbag systems have required a separate airbag door and a tether or steel hinge mechanism to secure the door during a deployment. In addition, a scoring operation is necessary to ensure predictable, repeatable deployment characteristics. The purpose of this paper is to demonstrate the development and performance of a cost-effective soft instrument panel with a seamless airbag door that results in a reduced number of parts and a highly efficient manufacturing process. Because of the unique characteristics of this material, a cost-effective, lightweight solution to meet both styling requirements, as well as safety and performance criteria, can be attained. |
A Robust Procedure for Convergent Nonparametric Multivariate Metamodel Design | Fast-running metamodels (surrogates or response surfaces) that approximate multivariate input/output relationships of time-consuming CAE simulations facilitate effective design trade-offs and optimizations in the vehicle development process. While the cross-validated nonparametric metamodeling methods are capable of capturing the highly nonlinear input/output relationships, it is crucial to ensure the adequacy of the metamodel error estimates. Moreover, in order to circumvent the so-called curse-of-dimensionality in constructing any nonlinear multivariate metamodels from a realistic number of expensive simulations, it is necessary to reliably eliminate insignificant inputs and consequently reduce the metamodel prediction error by focusing on major contributors. This paper presents a robust data-adaptive nonparametric metamodeling procedure that combines a convergent variable screening process with a robust 2-level error assessment strategy to achieve better metamodel accuracy. A door seal gap example is presented to illustrate the effectiveness and efficiency of the procedure. |
Most Efficient Practice of Nearfield Measurements Inside a Car for Improving Acoustic Comfort | A continuously growing demand comes from the automotive industry for optimization of materials and sound insulating products implementation inside the car, so as to propose the best acoustic performance at reduced costs. The acoustical holography system dBVISION developed by 01dB Acoustics & Vibration provides part of the solution to such a demand. Its demonstrated capability of measuring the acoustic field inside a vehicle makes it an advanced tool for performing extensive studies of the acoustic transparency of car openings as well as wind tunnel measurements. The developed technique allows now for: 1- Detailed localization of noise sources or acoustic weakness points inside the vehicle, 2- Knowledge of the acoustic energy distribution on elementary surfaces (such as doors, windscreen, roof, sealing system, etc.), 3- Reconstruction of the energy radiated by elementary surfaces in order to predict the acoustic pressure at the driver's and passengers' ears, 4- Estimation of the acoustic incidence of local modifications on components of the tested car. Technical background, together with the main features of this acoustical imaging system, will be exposed and the presentation will illustrate with practical examples how this fits to the project engineer process considering new acoustically driven design methods for a complete understanding and control of all components and systems involved in the car performance. |
New-Generation PC/ABS Blends Help Meet Performance & Styling Requirements for Instrument Panel & Other Interior Components | New targets for auto-interior components seek to improve thermal aging, low-temperature impact strength, recyclability, emissions/odor, processing productivity, and costs in order to meet new requirements for a 10-year car and new standards for consumer comfort. The pace of these demands is creating opportunities for blending technologies in a range of applications, including instrument panels, glove-box doors, top covers, retainers, and trim. A new generation of high-performance polycarbonate/acrylonitrile-butadiene-styrene (PC/ABS) resins based on proprietary formulation technology has been specifically developed to meet these demands in IP and other interior applications. This paper will focus specifically on a high-impact grade for IPs (in both standard- and low-emission formulations). This new technology was benchmarked against several earlier generation products from the same family, a new high-flow version using the same technology, and several competitive offsets. The results show a new class of PC/ABS blends offering best-in-class thermal aging, hydrolytic stability, low-temperature impact strength, and - for select applications - excellent odor and emissions. This has been accomplished without sacrificing processing performance. In fact, the new grades offer a broader processing window and faster cycle times for increased productivity and lower part costs. |
Vehicular Electrical System Under Value Engineering Optic | This work shows the ?쏺alue Methodology??application looking for to identify new alternatives for vehicular electrical energy system (battery, starter, generator, coils etc.). These alternatives must be feasible to the nowadays automobiles system. The electrical system studied in this job points out to engine with its main assembled options, or accessories, as air-conditioning, hydraulic power system (HPS), electrical lifter window, a thief deterrents alarm, door lockers, etc. Heavy electrical traffic conditions, which demand more energy, representing a bigger electrical charge, are being considered in this analysis. The main focus of this job is to show the internal parts reduction, meaning a better final cost to suppliers and carmakers, and consequently a better vehicle performance. Improvements achieved through this study must be appreciated. |
Anti Pinch Protection for Power Operated Features | Due to the ever-increasing number of power operated features in today's motor vehicle ??electric window openers with auto-up function, power doors and lift gates, to mention just a few ??and, of course a desire for more and more luxury features, safety is becoming a more and more important topic. This discourse describes the technology and the application of tactile (pressure sensitive) anti pinch systems and a non-touch (presence sensing) system which works on the basis of ultrasound. These systems are designed to be used as an alternative or in addition to indirect, motor-controlled anti pinch systems. |
The History of Laminated Steel | This paper discusses the background and history of ?쐋aminated steel??(commonly called ?쐍oiseless steel??or MPM). It provides the early development, where it came from, and how it was introduced to North America as a new tool for engineering acoustical solutions. A progressive timeline shows laminated steel from its earliest inception in Europe to its current role in today?셲 global market. Case histories along with examples of successful applications detail its important contribution in advancing the technology for component damping. Many manufacturing sources as well as end users have been impacted over the decades since it was first introduced. Some of those companies will be noted. The background information for this paper is provided by many of the individuals who were involved in the very early stages of its introduction as well those who are currently working to utilize the technology of laminated steel. |
An Acoustic Target Setting and Cascading Method for Vehicle Trim Part Design | One of the major concerns in the vehicle trim part design is the acoustic targets, which are generally defined by absorption area or coefficients, and sound transmission loss (STL) or sound insertion loss (SIL). The breaking down of acoustic targets in vehicle design, which is generally referred to as cascading, is the process of determining the trim part acoustic targets so as to satisfy full vehicle acoustic performance. In many cases, these targets are determined by experience or by subjective evaluation. Simulation based transfer path analysis (TPA), which traces the energy flow from source, through a set of paths to a given receiver, provides a systematic solution of this problem. Guided by TPA, this paper proposes a component level target setting approach that is based on the statistical energy analysis (SEA), an efficient method for vehicle NVH analysis in mid and high frequencies. Using a validated SEA model of the vehicle under consideration, the contributions of common noise sources and paths, which are generally defined on parts of sheet-metal with trim parts attached, can be evaluated. This allows the prediction of interior noise level due to various possible sound packages. On the base of this, acoustic target setting of trim parts can be defined as the solution of a mathematical optimization problem. The targets such as SIL of trim parts at certain frequency range are taken as design variables, and the vehicle level performance like the sound pressure level (SPL) at driver?셲 ear is incorporated into constraint functions. This approach is versatile and is suitable for traditional ICE vehicles and modern EVs. It can be used on a vehicle prototype at the early stages for target cascading, or on an existing vehicle model for NVH improvement. Several cases and examples on this target setting method have been discussed in the paper. |
Inverse Vibration Problem Used for the Characterization of the Damping Added by a Trim Foam on a Plate | Many solutions exist to insure the NVH comfort of ground and air vehicles, like heavy mass (bitumen pads), viscoelastic treatments and absorbing foams. The trim foam appears as an alternative to heavy solutions. To know the potential of these foams, a study of their capacities to damp vibration is done. A system, composed of a suspended plate, with a foam on it, is characterized in different contact conditions at the foam-plate interface (glued or not) and with different foam type. An experimental test facility is developed to identify the global damping of the structure: a laser vibrometer measures the displacement field of the foam-plate structure, and then an inverse method is used to determine the structural parameters. By changing the contact at the interface, it is possible to identify the contribution of the friction forces to the global damping of the structure. Another type of damping is the viscoelastic damping due to the intrinsic characteristics of the trim foam. With the help of FEA, it is possible to understand the influence of the damping effect. The implemented inverse methods are the Force Analysis Technique (FAT) and the Corrected Force Analysis Technique (CFAT), originally used for effort identification on a system. They are based on the motion equation of the system and the displacement field. In this study, these methods allow to determine the structural parameters, such as the elastic storage modulus and the loss factor. |
Study of the Glass Contribution to the Interior Acoustics of a Car and Related Countermeasures | This paper shows that the combination of a glass and passive acoustic treatment manufacturers can bring different benefits and considerably improve the interior acoustics of a vehicle. Glazing contributes to the design of the vehicle in addition to its primary role, good visibility and safety. From an acoustic point of view, this brings a challenge for the interior comfort. Indeed, glazing has no absorption and classically has an acoustic insulation weakness around its coincident frequency. In most of the cases, these different aspects make glazing one of the main contributors to the sound pressure level in the passenger compartment, and the trend is not one of change. However, there are possible countermeasures. One of which is the use of laminated glazing with acoustic PVB. This solution allows reducing the loss of insulation performance at the coincidence frequency. The other is the usage of passive interior acoustic trims. When properly positioned and optimized, the latter can be very effective and can tackle the frequency range that poses a problem. Especially since some technologies allow, by their process, to choose between the improvements of insulation or absorption. The aim of this paper is to understand the impact of the glazing on the interior acoustic for tires excitations. For that study, a measurement campaign together with some simulations models (FE and SEA) have been carried over on a European C-segment vehicle. A ranking of the different contributions is proposed. Then, in a second part, the countermeasures to improve the interior sound pressure level by adding optimized glazing and sound packages are presented. |
Using Statistical Energy Analysis to Optimize Sound Package for Realistic Load Cases | The statistical energy analysis (SEA) is widely used to support the development of the sound package of cars. This paper will present the preparation of a model designed to investigate the sound package of the new Audi A3 and associated correlation against measurements. Special care was given during the creation of the model on the representation of the structure to enable the analysis of structure borne energy flow on top of the classical airborne analysis usually done with SEA. The sound package was also detailed in the model to allow further optimization and analysis of its performance. Two real life load cases will be presented to validate the model with measurements. First, the dominating powertrain and a second load case with dominating rolling noise. An analysis of the contribution of the different source components and a way to diagnose the weak paths of the vehicle will be presented. The focus of this investigation is the application of optimally adjusted treatment. |
Extended Solution of a Trimmed Vehicle Finite Element Model in the Mid-Frequency Range | The acoustic trim components play an essential role in Noise, Vibration and Harshness (NVH) behavior by reducing both the structure borne and airborne noise transmission while participating to the absorption inside the car and the damping of the structure. Over the past years, the interest for numerical solutions to predict the noise including trim effects in mid-frequency range has grown, leading to the development of dedicated CAE tools. Finite Element (FE) models are an established method to analyze NVH problems. FE analysis is a robust and versatile approach that can be used for a large number of applications, like noise prediction inside and outside the vehicle due to different sources or pass-by noise simulation. Typically, results feature high quality correlations. However, future challenges, such as electric motorized vehicles, with changes of the motor noise spectrum, will require an extension of the existing approaches. In this paper, the vibro-acoustic frequency response of an existing MSC Nastran FE model is extended using the Actran Statistical Energy Analysis (SEA) approach, Virtual SEA. In Virtual SEA, the necessary information required to build the SEA system is extracted from the FE models. The fluid-structure Coupling Loss Factors (CLF) are computed through the Statistical modal Energy distribution Analysis (SmEdA) method. This method is a suitable candidate to account for acoustic trim effects based on analytical approach. The case studied consists of a trimmed body car model transfer function calculation. The result of the case study is an extensive correlation study containing measured and simulated transfer functions in low and mid-frequency range. Simulation results are derived from two approaches, FE method and Virtual SEA method. |
Linking Body-In-White and Trimmed Body Dynamic Characteristics in View of Body-In-White Mode Shape Target Setting | Target setting at Body-In-White (BIW) level is typically done for natural frequencies of global modes. Target values are commonly set based on experience or from benchmark studies with competitor vehicles. A link between these targets at BIW level and the vibro-acoustic targets at Trimmed Body (TB) level is not yet well established. Therefore, it is not always guaranteed that the TB targets will be met when the targets at BIW level are reached. Also, the other way around, not reaching a frequency target for a certain BIW mode does not necessarily imply that TB targets will not be met. Hence, there is a clear need for getting more insights in the relation between BIW dynamic properties and TB vibration behavior. In this paper techniques will be presented that establish the link between BIW and TB dynamic behavior. In addition, a large DOE campaign has been carried out to further link these dynamic properties to specific areas in the body design. Key elements in this paper are the introduction of a novel modal reduction method to extract the essential information from a large set of TB modes and a subspace correlation technique to link the critical TB modes with the global BIW modes. The results obtained with this study demonstrate that it is not enough to consider only natural frequencies of the BIW modes as a target but that their shape must be taken into account as well. |
Evaluation of Laminated Side Glazing and Curtain Airbags for Occupant Containment in Rollover | By their nature as chaotic, high-energy events, rollovers pose a high risk of injury to unrestrained occupants, in particular through exposure to projected perimeter contact and ejection. While seat belts have long been accepted as a highly effective means of retaining and restraining occupants in rollover crashes, it has been suggested that technologies such as laminated safety glazing or rollover-activated side curtain airbags (RSCAs) could alternatively provide effective occupant containment. In this study, a full-scale dolly rollover crash test was performed to assess the occupant containment capability of laminated side glazing and RSCAs in a high-severity rollover event. This allowed for the analysis of unrestrained occupant kinematics during interaction with laminated side glazing and RSCAs and evaluation of failure modes and limitations of laminated glazing and RSCAs as they relate to partial and complete ejection of unrestrained occupants. The dolly rollover was performed with a 2010 Chevrolet Express at a nominal speed of 43 mph, with unbelted anthropomorphic test devices (ATDs) positioned in the driver, right front passenger, and designated third, fourth, and fifth row seating positions. Vehicle dynamics and occupant kinematics were analyzed through evaluation of vehicle instrumentation, on-board and off-board real-time and high-speed video, post-test survey of the debris field, and post-test inspection of the vehicle and ATDs. Neither laminated side glazing nor RSCAs prevented complete or partial ejection of the ATDs. Two of the ATDs were completely ejected during the dolly rollover and six other ATDs were partially ejected. Fracture and peripheral separation of laminated side glazing was observed in association with ground contact, vehicle deformation, and ATD loading. Ejection in seating positions adjacent to RSCAs was observed in association with ATD loading and out-of-position interaction with the airbags. The findings of the present study demonstrate that laminated side glazing and rollover-activated side curtain airbags are not substitutes for proper seat belt use. |
Enhanced Windshield CAE NVH Model for Interior Cabin Noise | This paper describes a reliable CAE methodology to model the linear vibratory behavior of windshields. The windshield is an important component in vehicle NVH performance. It plays an integral role in interior cabin noise. The windshield acts as a large panel typically oriented near vertical at the front of vehicle?셲 acoustic cavity, hence modeling it accurately is essential to have a reliable prediction of cabin interior noise. The challenge to model the windshield accurately rises from the structural composition of different types of windshields. For automotive applications, windshields come in several structural compositions today. In this paper, we will discuss two types of windshield glass used primarily by automotive manufacturers. First type is the typical laminated glass with polyvinyl butyral (PVB) layer and second type is the acoustic glass with PVB and vinyl layers. Acoustic glass improves acoustic characteristics of the glass in a frequency range of ~ 1200 Hz to ~4000 Hz. Low frequency interior cabin noise studied with Finite Element Analysis (FEA) is typically below 400 Hz. The acoustic glass doesn?셳 provide substantial benefits in this range and in many cases we see an adverse contribution at lower frequencies since the acoustic windshield tend to be softer. In this paper, frequency dependency of PVB layer and acoustic vinyl layers are investigated. Multiple modeling techniques for windshield are demonstrated and the results are compared to physical tests. Finally an enhanced windshield modeling technique for low frequency interior cabin noise is proposed. |
Virtual Verification of Light Reflection for Cluster and Side Mirror in Real Time Scenario | In the very automobile world trends are changing at a very fast pace, due to continuous expectation changes by user and new regulatory requirements demand from government authorities with a very stringent timeline. In the current scenario, manufacturer has to wait for mock up for concept selection and physical proto build to conclude open points of design verification. This complete process takes more than a year to enhance the design maturity for further builds. In VECV we have created Cluster design standard to meet different level of cluster illumination & reflection at virtual level. We are defining the cluster light illumination based on our rigorous study on cluster reflection impact on side glass, windscreen and mirror. Accordingly we have packaged our mirror to minimize the impact of cluster reflection on mirror visibility. With the help of virtual verification of cluster and Side mirror inter co-relation of packaging, we significantly reduced the time loss and save huge cost required for developing proto build. Different options of mirror and cluster can be verified in quick session. With the help of virtual verification of mirror and cluster we are able to meet different regulatory compliances for light illumination without building a single proto build. |
Road Noise Prediction Assessment Using CAE Instead of Costly and Time Consuming Physical Tests | Virtual Product Development (VPD) with a vision to eliminate prototype testing is the recent trend in the automotive industry. Reducing the total vehicle development period with optimized output has been the major advantage of this new trend, fueled by increasing competition and shorter product life cycle. In this regard, Computer Aided Engineering (CAE) has taken a more significant role than ever in the vehicle development programs. Prediction of road noise in passenger cars is one of the important attributes to NVH (Noise Vibration Harness) Simulations. In the present work, CAE - NVH simulation of road noise is carried out on the finite element model of the vehicle, eliminating the costly and laborious test procedures & the process of awaiting information from various departments. One of the major challenges in these simulations are generating the load inputs for the structure-borne road noise in a cost and time saving method with accuracy. An alternative to the existing MBD/Test input method is explored in the present work. Enforced displacements in the frequency domain are generated using ISO 8608 standard road profiles and are used as input to the vehicle system. Time and cost of the total procedure is reduced drastically by this procedure with more than acceptable accuracy & correlation. The results are validated with the available test data & existing MBD CAE input methods of predicting the interior noise of the passenger cars. |
Prediction of Aeroacoustical Interior Noise of a Car, Part-2 Structural and Acoustical Analyses | One-way coupled simulation method that combines CFD, structural and acoustical analyses has been developed aiming at predicting the aeroacoustical interior noise for a wide range of frequency between 100 Hz and 4 kHz. Statistical Energy Analysis (SEA) has been widely used for evaluating transmission of sound through a car body and resulting interior sound field. Instead of SEA, we directly computed vibration and sound in order to investigate and understand propagation paths of vibration in a car body and sound fields. As the first step of this approach, we predicted the pressure fluctuations on the external surfaces of a car by computing the unsteady flow around the car. Secondly, the predicted pressure fluctuations were fed to the subsequent structural vibration analysis to predict vibration accelerations on the internal surfaces of the car. Finally, an acoustical analysis was performed to predict sound fields in the cabin by using particle velocities of sound on the interior surfaces of the car, predicted by the structural analysis. To transfer predicted surface data, such as pressure fluctuations, vibration accelerations and particle velocities of sound, from one simulation to another, we adopted a parallel coupling tool. As the second part of our research, this paper presents results of the structural vibration analysis and that of the acoustical analysis, together with those measured by wind tunnel tests. In our research, a light automobile, for which all the interior components were removed and the underfloor shape was simplified, was employed for a case study. The wind tunnel tests were performed with a freestream velocity of 100 km/h. Both the predicted interior surface accelerations and interior noise level agreed well with the measured equivalents up to 2 kHz. |
Aero-Vibro-Acoustic Wind Noise-Simulation Based on the Flow around a Car | Aim of the ongoing development of passenger cars is to predict the interior acoustics early in the development process. A significant noise component results from the flow phenomena in the area of the side window. Wind noise is a physical problem that involves the three complicated aspects each governed by different physics: The complex turbulent flow field in the wake of the a-pillar and the side mirror is characterized by velocity and pressure fluctuations. The flow field generates sound which is transmitted into the passenger cabin. In addition to that, it excites the structure, resulting in a radiation of structure-borne noise into the interior of the car. Therefore, the sound generation is governed by fluid dynamics of the air flow. The sound transmission through the structure due to vibrations is determined by structural mechanics of the body structure. The sound propagation inside the cabin is influenced by interior room acoustics. In the present work, different CFD simulations of the exterior flow were conducted to investigate the sound generation due to external air turbulence. For this purpose, a simplified model of an automobile was used. Additionally vibro and aeroacoustic simulations were conducted to solve the other two parts of the problem and to gain insight into the sound transmission into the passenger cabin. |
The Application of Superelement Modeling Method in Vehicle Body Dynamics Simulation | In this paper, we propose a method of dynamics simulation and analysis based on superelement modeling to increase the efficiency of dynamics simulation for vehicle body structure. Using this method, a certain multi-purpose vehicle (MPV) body structure was divided into several subsystems, and the modal parameters and frequency response functions of which were obtained through superelement condensation, residual structure solution, and superelement data restoration. The study shows that compared to the traditional modeling method, the computational time for vehicle body modal analysis can be reduced by 6.9% without reducing accuracy; for the purpose of structural optimization, the computational time can be reduced by 87.7% for frequency response analyses of optimizations; consistency between simulation and testing can be achieved on peak frequency points and general trends for the vibration frequency responses of interior front row floors under accelerating conditions. The results indicate that the method has good engineering value, and is suitable for the study of dynamics problems of vehicle bodies. |
In-Cabin Aeroacoustics of a Full-Scale Transport Truck | The noise generated by the flow of air past a transport truck is a key design factor for the manufacturers of these vehicles as the sound levels in the cabin are a significant component of driver comfort. This paper describes a collaboration between Volvo GTT and the National Research Council Canada to measure the in-cabin aeroacoustics of a full-scale cab-over tractor in the NRC 9 m Wind Tunnel. Acoustic instrumentation was installed inside the tractor to record cabin noise levels and externally to acquire tunnel background noise data. Using a microphone mounted on the driver?셲-side tunnel wall as a reference to remove variations in background noise levels between data points, differences in cabin noise levels were able to be detected when comparing the tractor with different configurations. The good repeatability of the data allowed for differences of as little as 0.5 dB to be measured. A procedure to estimate the transfer function from the wall reference microphone to the cabin microphones was implemented which, though of limited success, provided insights into the acoustic environment of the test section. The main conclusion of this project is that aeroacoustic measurements can be carried out in the NRC 9 m Wind Tunnel in conjunction with an aerodynamic entry for full-scale transport trucks. |
Vibration Test Machine and Operation Procedure | This SAE Recommended Practice provides procedures, and information to conduct vibration (impact) tests on lighting devices and their components as well as other safety equipment used on vehicles. |
Collision Deformation Classification | The purpose and scope of this SAE Recommended Practice is to provide a basis for classification of the extent of vehicle deformation caused by vehicle accidents on the highway. It is necessary to classify collision contact deformation (as opposed to induced deformation) so that the accident deformation may be segregated into rather narrow limits. Studies of collision deformation can then be performed on one or many data banks with assurance that the data under study are of essentially the same type.1 The seven-character code is also an expression useful to persons engaged in automobile safety, to describe appropriately a field-damaged vehicle with conciseness in their oral and written communications. Although this classification system was established primarily for use by professional teams investigating accidents in depth, other groups may also find it useful. The classification system consists of seven characters, three numeric, and four alphameric, arranged in a specific order. The characters describe the deformation detail concerning the direction, location, size of the area, and extent which, combined together, form a descriptive composite of the vehicle damage. The individual character positions are referred to by column number for identification and computer storage compatibility as illustrated in Figure 1. The definition of each classification is provided in subsequent sections. An Appendix is also provided to assist in application and interpretation. |
Integrated Mechatronic Design and Simulation of a Door Soft Close Automatic with Behavioral Models of Smart Power ICs | Based on the example of a door soft close automatic the potential of integrated system simulation in the automotive systems development is demonstrated. The modeling approach is covering several physical domains like mechanics, electromagnetics and semiconductor physics. With adequate simplifying methods a time efficient model is generated, which allows system optimization in the concept phase. Time consuming redesigns can thus be minimized. |
Highly Efficient Robust Optimization Design Method for Improving Automotive Acoustic Package Performance | To consider the influence of uncertainty in the design process of automotive acoustic packages, the robustness of the acoustic packaging system performance must be improved, and the low-efficiency problem of the two-layer nesting robustness optimization model must be solved. This article proposes a highly efficient robustness optimization design method for improving the performance of the automotive acoustic package. First, the full vehicle model was established based on the statistical energy analysis method, and the accuracy of the model was verified through acoustic transfer function (ATF) testing. The parameters affecting the sound absorption and insulation performance of the key acoustic packaging parts were selected as the uncertain parameters, and their sensitivity was analyzed. The possibility degree method of interval numbers was introduced to convert the two-layer nesting robustness optimization model to a single-layer optimization model, and the efficient robust design of the automotive acoustic packaging was realized. The acoustic packaging parts of a sport utility vehicle (SUV) were analyzed and optimized using the proposed efficient and robust optimization method. After optimization, the total mass of the acoustic packaging parts decreased by 10.8%, the radius of the perturbation interval of the interior noise decreased by more than 25% compared with the initial value, and the robustness of the system greatly improved. |
Strat-X | Experiments in space can be expensive and infrequent, but Earth?셲 upper atmosphere is accessible via large scientific balloons, and can be used to address many of the same fundamental questions. Scientific balloons are made of a thin polyethylene film inflated with helium, and can carry atmospheric sampling instruments on a gondola suspended underneath the balloon that eventually is returned to the surface on a parachute. For stratospheric flights between 30 and 40 km above sea level, balloons typically reach the float altitude 2-3 hours after launch, and travel in the direction of the prevailing winds. |
Access System Senses Finger Vibrations to Verify Users | The market for smart security access systems is expected to grow rapidly, reaching nearly $10 billion by 2022. Today's smart security access systems mainly rely on traditional techniques that use intercoms, cameras, cards, or fingerprints to authenticate users. These systems require costly equipment, complex hardware installation, and diverse maintenance needs. |
Smart Fabric Stores Information Without Electronics | Conductive thread ??embroidery thread that can carry an electrical current ??often is combined with other types of electronics to create fabric that lights up or communicates. This thread also has magnetic properties that can be manipulated to store either digital data, or visual information like letters or numbers. This data can be read by a magnetometer, an inexpensive instrument that measures the direction and strength of magnetic fields, and is embedded in most smartphones. |
Level Zero HERO | Wrangler Rubicon has 10.9 in of ground clearance and industry-leading approach, departure and breakaway angles to uphold its heritage for off-road dominance. Okay, maybe the 2018 Jeep Wrangler could be considered SAE autonomy Level 0.5- after all, the all-new version of Jeep's icon does offer a couple of automated driver-assist features. If you must. But apart from that concession to contemporary development trends, the new Wrangler is unabashed in its dedication to the analog driving experience: It's updated, upgraded and more refined, but it's unquestionably the most elemental new vehicle of 2018. After all, name another all-new model that pridefully comes to market at the dawn of the automated-driving epoch with solid front and rear axles, a windshield that folds down and doors that come off. |
Delayed Latching Mechanism | Uncontrolled and rapid movement of equipment and people through security gates has been a major problem for security personnel. In situations pertaining to facility security, it is desirable to delay the passage of a person through an entrance or an exit for a small interval of time, such as several seconds or up to a minute. Often, authorization to proceed is provided by an electronic signal to unlock the passageway. Such electronic signals are initiated remotely by a person in authority, such as a guard in a control room viewing a security camera, or a person who verifies the identity of the requester through a two-way audio connection. |
42V PowerNet in Door Applications | This article describes the effects of a future 42V automotive electrical system on the vehicle electronics, focusing mainly on the consequences for power semiconductors and their associated technologies. Taking the example of a door module, it then shows how existing 14V loads can be operated on the 42V PowerNet and what advantages result for operation of adjusted 42V loads. The following different problem-solving approaches are presented for typical loads such as power windows, electrically positioned and heated outside mirrors, and central locking: Power windows: A test motor specially developed for the 42V supply is continuously operated directly from the electrical system using suitable power semiconductors. Central locking: A conventional 14V motor is operated at 42V, its operating point being set using pulse width modulation (PWM). Remaining door module: Smaller 14V mirror motors and the control electronics are supplied from a second 14V system. This second supply can be taken from the current 14V system or generated locally by appropriate switching regulators, or even by a central DC/DC converter from 42V. |