Theory and practice of cushion curve: A supplementary discussion

Abstract

The practice of developing cushion curves has been applied for many years. Known for its tedious development, the process does not correlate to cushion configurations too. This study reviewed conventional theories, practice of cushion curves, and simplified methods, including the conversion from quasi‐static compression chart to cushion curves, and testing‐extrapolated methods based on several applicable tests. In addition, the study examined the effect of configuration on cushion curves. Discussion indicated that the theories of cushion curves are based on two fundamental properties in physics: energy conversion and Newton's second law. Energy density‐based test‐extrapolation approaches reduced the development time significantly without compromising the accuracy of the cushion curves. The edge and corner cushion structure showed a similar pattern to the conventional flat cushion curve, but were shifted horizontally to the right. This paper recommends packaging engineers to apply C‐e curves as the basis of the cushion curves to design cushioning. Finally, energy dissipated during platen drop test is discussed to explain the deformation process in relation to dynamic stress‐strain curve and cushion curve.