Multi-scale Modelling of Fracture in Open-Cell Metal Foams

Abstract

Metal foams possess attractive mechanical properties like high stiffness to weight ratio.When used to build light-weight structures they require a good combination of strength and ductility. They are ductile under compression but rather brittle in tension with a few percent of overall strain to fracture. Second-phase particles, grain boundary precipitates and inclusions are often associated with the knock-down of the ductility [1]. Through a heat treatment the microstructure can be changed, however, this also changes the associated yield stress and hardening behaviour of the strut material. How this will affect the overall behaviour depends sensitively on the foam’s cellular architecture, e.g. the cell size and shape distribution, the cross-sectional geometry of the strut, and its relative density. The goal of this work is to study these dependencies using a multi-scale modelling framework that takes all these ingredients into account. In this paper, we present the combined effect of the solid material strain hardening and the relative density on the initiation and accumulation of damage and overall strength of the structure.