Tensile fatigue of conventional and negative Poisson's ratio open cell PU foams

In this paper, we present a comparative analysis between the cyclic loading tensile behaviour of conventional and auxetic thermoplastic PU foams. While the two types of foam share the same base material (open cell PU-PE), one batch is transformed into an auxetic one (i.e., negative Poisson's ratio) using a special manufacturing process involving moulding and exposure to particular temperature profiles to stabilise the transformation of the microstructure. The effect of the stiffness degradation and accumulation of energy dissipation versus the number of cycles are discussed for different loading levels r. The results show that the fatigue behaviour until failure, subjected to cyclic loading depends on the loading levels and occur in three stages. The results obtained shows also that the auxetic foam have enhanced characteristics under static loading and tensile fatigue compared to the conventional parent phase form. Crown Copyright (C) 2008 Published by Elsevier Ltd. All rights reserved.