to the natural frequency of the cushioned item. Design for vibration protection The process for vibration protection (or isolation) involves similar considerations as that for shock. Cushions can be thought of as performing like springs. Depending on cushion thickness and load-bearing area and on the forcing vibration frequency, the cushion may 1) not have any influence on input vibration, 2) amplify the input vibration at resonance, or 3) isolate the product from the vibration. Proper design is critical for cushion performance. Evaluation of finished package Verification and validation of prototype designs are required. The design of a package and its cushioning is often an iterative process involving several designs, evaluations, redesigns, etc. Several (ASTM, ISTA, and others) published package testing protocols are available to evaluate the performance of a proposed package. Field performance should be monitored for feedback into the design process. ASTM Standards D1596 Standard Test Method for Dynamic Shock Cushioning Characteristics of Packaging Material D2221 Standard Test Method for Creep Properties of Package Cushioning Materials D3332 Standard Test Methods for Mechanical-Shock Fragility of Products, Using Shock Machines D3580 Standard Test Methods for Vibration (Vertical Linear Motion) Test of Products D4168 Standard Test Methods for Transmitted Shock Characteristics of Foam-in-Place Cushioning Materials D4169 Standard Practice for Performance Testing of Shipping Containers and Systems D6198 Standard Guide for Transport Packaging Design D6537 Standard Practice for Instrumented Package Shock Testing For Determination of Package Performance and others See also Impact force Packaging and labeling Shock Shock absorber Shock response spectrum Vibration Vibration isolation Buffer (disambiguation) Damped wave Damping ratio Damper (disambiguation) Betagel, utilizes gel and silicone to absorb violent shocks Coefficient of restitution Notes Further reading MIL-HDBK 304C, “Package Cushioning Design”, 1997, Russel, P G, and Daum, M P, "Product Protection Test Book", Institute of Packaging Professionals Root, D, “Six-Step Method for Cushioned Package Development”, Lansmont, 1997, http://www.lansmont.com/ Yam, K. L., "Encyclopedia of Packaging Technology", John Wiley & Sons, 2009, Singh, J., Ignatova, L., Olsen, E. and Singh, P., "Evaluation of the Stress-Energy Methodology to Predict Transmitted Shock through Expanded Foam Cushions", ASTM Journal of Testing and Evaluation, Volume 38, Issue 6, November 2010 External links Institute of Packaging Professionals International Safe Transit Association Westpak webinar on protective packaging Packaging Plastics applications da:Emballage de:Verpackung es:Embalaje fr:Emballage