Effect of defects on elastic-plastic behavior of cellular materials

Cellular solids such as foams are widely used in engineering applications. In these applications, it is important to know their mechanical properties and the variation of these properties with the presence of defects. Several models have been proposed to obtain the mechanical properties of cellular materials. However, these models are usually based on idealized unit cell structures, and are not suitable for finding the mechanical properties of cellular materials with defects. The objective of this work is to understand the effect of missing walls and filled cells on elastic-plastic behavior of both regular hexagonal and non-periodic Voronoi structures using finite element analysis. The results show that the missing walls have a significant effect on overall elastic properties of the cellular structure. For both regular hexagonal and Voronoi materials, the yield strength of the cellular structure decreases by more than 60% by introducing 10% missing walls. In contrast, the results indicate that filled cells have much less effect on the mechanical properties of both regular hexagonal and Voronoi materials. The effects of material strain hardening on the yield strength of cellular materials are also investigated. (c) 2007 Elsevier B.V. All rights reserved.