Mechanical behavior of closed cell plastic foams used as cushioning materials

Two methods for the prediction of force–deformation curves of closed cell plastic foams at any strain rate from a limited number of experiments are described. These methods are based on the “modified Boltzman integral model” and on the “reference model.” Both methods use constitutive equations and experimentally determined parameters. The modified Botlzman integral model uses data obtained in a limited number of stress–relaxation experiments while the reference model uses a very limited number of stress–relaxation and one force–deformation curve data. Both models predict well the force–deformation curves, the reference model providing somewhat better predictions.