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A new method for the determination of cushion curves

A new method for the measurement of shock‐absorbing characteristics of cushioning materials and determination of ‘cushion curves’ is discussed in this paper. The method not only significantly reduces testing time but also improves the accuracy of the estimate of a cushion curve. Cushion curves are determined from the material's static compression characteristics and the impact data (static load/peak acceleration) obtained from a small number of impacts on a cushion tester. However, the method is capable of producing a cushion curve from the measurement of just a single impact. The process involves an iterative least mean squares (ILMS) minimisation of the discrepancy between peak acceleration values predicted from a theoretical model and measured in the impact tests. The algorithm of the ILMS method, examples demonstrating its application and the dynamic effect in impacts of various materials such as the EPU, the EPS and corrugated fibreboard are presented. Copyright © 2000 John Wiley & Sons, Ltd.