Predicting the Effect of Temperature on the Shock Absorption Properties of Polyethylene Foam

Polyethylene (PE) foam is a material used commonly in protective packaging for its shock absorption properties. When developing a package design intended to mitigate shock to the product, decisions are typically made based on established cushion evaluation procedures performed at standard laboratory conditions. Distribution environment temperatures, however, can vary greatly from the condition at which these materials are assessed. The research presented in this paper utilizes the stress-energy method of cushion evaluation and highlights temperature-dependent trends in the stress-energy equations of PE foam tested at 12 different temperatures, ranging from -20 degrees C to 50 degrees C. A quadratic polynomial is used to describe the variation in the stress-energy equation coefficients over the temperature range evaluated. The model developed enables cushion curve prediction for any static stress, drop height, material thickness and temperature expected over the intended range of use of the material. This model is validated by performing additional impact testing of samples at various temperatures and comparing experimentally obtained acceleration values to those predicted by the model. Further model analysis is performed to estimate the optimal static stress for the material at any temperature within the range tested and to study the variation with temperature of this optimal point. Results reveal that the model developed is capable of predicting the shock absorption properties of the material within the range of parameters tested and that the optimal static stress of the material decreases as temperature increases from -20 degrees C to 50 degrees C. Application to cushion design is made to recommend an approach to designing a PE cushion system for use over a range of temperatures. Copyright (C) 2016 John Wiley & Sons, Ltd..