Seminars Archive

A simple approach to evaluate high strain rates mechanical behaviour of low interconnected cell foams

Abstract
A method to model high strain rate compressive properties of PU foams was investigated. The nonlinear mechanical response of the foam was split into three independent contributions: foam morphology, time dependent polymer response, gas entrapped in the cells. The foam morphology contribution was estimated by a simple uniaxial compression test at very low strain rate. The time (temperature)-dependent behaviour of the polymeric foam was evaluated by stress relaxation tests. Due to the low degree of cell interconnections of the studied foam, at low strain rates the gas contribution was predicted by using a gas flow model derived from Darcy\'s law. Starting from 2s^-1 compressive strain rate the foam exhibited a transition and the gas contribution was evaluated by a scaled closed cell model. The proposed method is able to predict the mechanical response of foams at high strain rates using data obtained by few low strain rates mechanical tests.