Crash performance of cellular foams with reduced relative density part 1: rib thickness variation

Abstract

Finite element modelling at the macroscopic level is used to investigate the effect of varying the rib thickness of open cell conventional and re-entrant periodic foams on the crash performance due to energy absorption. The data show that the mechanical properties and, hence, crashworthiness vary not only with foam-relative density, but also on how the relative density variation is achieved. Reducing the ‘diagonal’ rib thickness leads to a more marked decrease in E y as well as in E x , whereas ν xy and ν yx both increase in magnitude. The results have implications for applications in which the crashworthiness is to be maximised or minimised with respect to reduction in the relative density. The crashworthiness of orthotropic re-entrant foams is also shown to be considerably greater than conventional foams in one principal direction.