RESPONSE OF ANISOTROPIC CRUSHABLE POLYMERIC FOAM TO IMPACT

Abstract

Polymeric foams are widely used in impact absorption, cushioning, and similar applications. During the chemical foaming process employed to fabricate them, the bubbles formed stretch in the foam-rise direction, resulting in elongated foam cells which possess structural and mechanical anisotropy. Investigation into the anisotropic (or more accurately transversely isotropic) response of polymeric foam is thus useful for its effective usage. Another factor that affects the mechanical response of foam is the speed at which it is deformed, and this is particularly important in applications involving impact energy absorption. However, very limited work has focused on the rate-sensitive mechanical response of anisotropic polymeric foam under compression in different directions. Therefore, a systematic investigation into the influence of loading direction and strain rate on the mechanical response of a polyurethane (PU) foam was undertaken; this included experiments, micro/meso-scale finite element (FE) simulation and constitutive modelling.