Measuring and mathematical modeling of cushion curves for polymeric foams

In this paper, we created a general mathematical equation for the cushion curves of polymeric foams, using the measurement results of drop weight impact tests on commercially available, closed-cell ethylene-vinyl acetate and cross-linked polyethylene foams of different densities. We found exponential relationship between the results of the drop tests and the static load, and investigated the effect of the input parameters on the fitted constants using analysis of covariance and multiple linear regression. In the second part of the study, we used a novel approach to theoretically determine the cushion curves of different thicknesses. We predicted material behavior using the Burgess method on the fitted exponential equations and assessed the limitations and accuracy of this extrapolation approach by comparing the measured and simulated data. We validated the results by quantifying the permanently damaged volume of the foams with the use of a 3D optical measuring system.