# Tag Info

12

The turbulence model can make a big difference in your simulation. There are many turbulence models around. It becomes a tough job to select one out of them. There is no perfect turbulence model. It all depends on several parameters like Reynold's number, whether the flow is separated, pressure gradients, boundary layer thikness and so on. In this answer, ...

8

It might be written that way because the transfer function of a second order system is written as: $$h(s) = \frac{\omega_n^2}{s^2 + 2\zeta \omega_n s + \omega_n^2}$$ where $\zeta$ is the relative damping ratio and $\omega_n$ is the natural frequency. So in your system \begin{align} \zeta &= 0.7 \\ \omega_n &= 52 \end{align} It's easy to see ...

5

It's the inverse of the acceleration of gravity g in imperial units. $$1 g = 386.1 in/s^2$$ $$1/g = 0.00259 s^2/in$$ You need that since: $$weight = mass * g$$

5

The short answer is, there is no amplitude used. Even more important though, is the fact that the displacements and stresses shown in the results of a modal analysis cannot be used to say anything about the physical behavior of the part in absolute terms. The basic equation of motion is $$[M][\ddot{U}]+[B][\dot{U}]+[K][U]=F(t)$$ $M$, $B$,and $K$ are ...

5

The amplitudes of the modes from a vibration analysis are arbitrary. Often they are "mass-normalized" which is mathematically convenient for using them in a subsequent step in the analysis. There may be an option to scale the in other ways, for example "engineer's normalization" where the largest deflection is set to 1.0, or the option to scale a specified ...

5

To convert a plot of J versus s to a plot of J/s vs s, take the derivative. Here is my quick-and-dirty answer after digitizing the data.

4

Okay so I ended up having a play in ANSYS Mechanical Workbench. I did a mock up of your problem. Here's how I've been able to successfully model it. Note that a lot of my decisions are based on the Contact Best Practices Guide from ANSYS. Here's some very important points given your problem but also for contact modelling in general and a frictionless ...

4

The type of machine that runs the simulation (e.g. super computer, slide rule, pen and paper, etc.) is less important than the physical and mathematical models that describe the process being simulated. Throwing more computing resources at a simulation whose fundamental equations are flawed will not improve the accuracy of the solution. To answer your ...

4

this is a typical engineering problem and has an equation approved by IBC numbered 18-1. $$d = 0.5 A{1 + [1 + (4.36h/A)]1/2}$$ The calculation process is I first calculate A =2.3* post load/(allowed passive soil bearing value*diameter of caisson) Then you plug A into EQ 18-1. The post resists overturning momentum mainly by rotating around a pivot under ...

3

The accuracy of a simulation depends more on how well your equations and assumptions model reality, than the resolution of the simulation (computing power, as Carlton has stated). More computing power does let you have your solution in much less time however. A model, by definition, is not the real thing. No model can be trusted unless it is tested in the ...

3

Without knowing more about your problem the first thing that you need to do is make sure that you are using the right geometry and elements. To use that representation you need to use: 2D geometry Mesh it as shells Assign a plain stress assumption

3

Conventional automatic transmissions have a torque converter which uses a viscous rather than a rigid coupling to connect input and output. This performs a similar function to a friction clutch but doesn't require manual engagement. Also automatic gearboxes are based on epicyclic gear trains so all the gears are permanently meshed with each other and ratios ...

3

There are several options for doing this: If there are only a few values to be saved per design point, you could use 'output parameters'. If there is a lot of data to be saved, the report generator may be useful. Some information can be found here: Working with Project Reports An APDL snippet can be used in the results* tree. Some information here: ...

3

My advice would be to forget about the mathematical theory and start thinking about what the engineering means. It's hard to think of any situation where the stiffness of a sensibly designed structure might vary "randomly" by a factor of a million, unless all the stiffness values are so high that the response is very insensitive to the stiffness value - and ...

2

@Narada is correct, but I their answer is a bit short on detail, so I will expand on it. Calculating Force First, you can calculate the force that the motor exerts on the containing object from the acceleration of the mass at the end of the motor shaft. As the mass rotates, it accelerates toward the motor shaft at a rate $\omega^2 y$, where $\omega$ is ...

2

I can't say that this will be the ideal answer, but it should get you started. As will be apparent, I not a true expert. The quality of these models will generally increase with their sophistication, which in this case basically tracks with the number of equations use. So (S-A) would be least effective while k-$\epsilon$, k-$\omega$ and SST would be better....

2

CircuitWorks doesn't simulate the electronics; it just integrates between some common PCB design software formats and SolidWorks for mechanical information. For example, maximum component height, location of heat sinks and mounting holes, keep-out areas, etc. It sounds like what you want is a plug-in that drives the mechanical constraints in SolidWorks (...

2

This sounds like the exact synopsis of my masters thesis. Theoretically a format that can contain this info exits. STEP could include this information, but since the exporter has some serious leeway into implementation so no export actually contains all you ask for and even if it did theres no guarantee your importer would understand it even if included. ...

2

Depending on the kind of engineer you ask you will get many different options to approach this - your question is pretty open-ended. As a Geotechnical Engineer I'd say your pole can be looked at as a retaining wall. Now, if the ground is modelled as real "dirt" it will have some give. What would happen is that the pole will rotate about some point in the ...

2

Either your definition of "completely" is a bit unusual, or there's something wrong with those charts, because in those charts, 1.6 x the model does not completely match any of the six observations you have (assuming the point values are at the centre of each shape). Either way: your model outputs don't match your observations, with or without a 1.6 fudge ...

2

This is a multi-physics analysis, there are some open source packages though i'm not familiar with them (OpenFOAM is open source CFD software, and COMSOL is example of an commercial multi-physics solver). If you're looking at writing your own, "a.s.a.p." (as soon as possible) is going to be not very soon as that takes a huge amount of work. The best ...

2

While the yield stress is a well defined point in materials such as steel or other metals, that is not the case when we talk about foams. Here they are calling "yield stress" to the whole volumetric strain-stress curve. So they are basically asking for a number of strain-stress curves at different strain rates. Or you can use material 63 if strain rate ...

2

I am not too familiar with the VCU, PV780, or PowerVision. Based on your description PV780 can be configured to be the Instrument Cluster Panel (ICP) for Engine Control Unit/Module (ECM) or Transmission Control Unit. To keep a response short I have selected a Temperature gauge of the IPC. There is a very good chance this information communicated to the IPC ...

2

Verify your model against actual physical hardware. If you're sure of parts of the model, and unsure of others, then just verify the parts you're worried about. If the physical hardware is big and expensive, then if possible build a simplified physical model that still captures the behavior you're concerned about.

2

You need to convert the torque at the axle into force against the ground through the tire (Force = torque/radius). Then F=ma for the entire mass of the car (plus if you want to be precise the rotational mass of the wheels, but this will be only a fraction of the mass of the car). Tire slip would be based on total force from the wheel versus friction ...

2

This is a common issue on all numerical methods (not just multibody problems), i.e. the tradeoff between the following three types of error: Round off error Discretization Truncation (sometimes the 2 and 3 are included in the same term). All of them are forms of quantization error. These three types have a dependence on mesh size (either spatial or ...

2

Try using a replacing a 9V VDC voltage source with a VAC voltage source. Pay attention to the frequency of the VAC voltage source. This should address the issue. With regard to determining the time value for a particular voltage, review PROTEUS DESIGN SUITE Getting Started Guide. In the section VSM tutorial (Graphs) read around page 230. You might have ...

2

It means that there is a positive offset of one. So your signal is $$x(t) = 1 + 2 \cdot \sin(\omega t)$$ where: 1 is the offset 2 is the amplitude of your signal (not 4).

2

Capacitance only depends on its geometry, ... False. Capacitance is also determined by the dielectric (the insulator) between the plates and this can have a huge effect on the value obtained. ... but the charging and discharging of the capacitor depend on a resistive load within the circuit. The load doesn't have to be purely resistive but we'll go with &...

1

There are 2 important human functions that an automatic transmission must replace: 1.The driver chooses a gear that's appropriate for the torque and speed requirements of the vehicle. In an automatic transmission, shift schedules are stored as breakpoints for upward and downward shifting, usually based on engine torque and speed. 2. The driver feathers the ...

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