Volume 39, Issue 6 (November 2011)
Evaluation of Predicted Deceleration Values From the Stress-Energy Method Compared to Actual Deceleration Values From the ASTM D1596 Test Method
In recent years a simplified method for generating cushion curves, called stress-energy, has been presented as an alternative to ASTM D1596. A frequent question regarding the stress-energy method is the accuracy of the predicted deceleration compared to actual deceleration. This study compares the predicted deceleration values from the stress-energy method to the actual deceleration values collected from the ASTM D1596 test method for several data sets of EPS and EPE molded foam. Results show the average difference between the stress-energy predicted deceleration and the actual ASTM D1596 deceleration values to be 10 % or less for 144.2 kg/m3 EPE. Evaluating 20.0 kg/m3 EPS, the average difference between predicted and actual deceleration values is about 12 % or less. The study also found drop to drop deceleration to vary widely, so average actual deceleration was also evaluated compared to the predicted stress-energy deceleration. As a result, both the EPE and EPS predicted deceleration can be shown to be within ±10% of the actual averaged deceleration, an accuracy useful for practical application.