Finite element analysis of yield functions of Kelvin foams with open cells

Abstract

Proper design of foams requires an understanding of the response of the materials to stress. This thesis, based on finite element analysis, provides numerical solutions in modeling the yield behavior of Kelvin foams. The FEA model, representing a complicated unit cell, was calculated and meshed. C++ programs were designed and implemented to generate meshes for unit cells. Finite element analyses were performed for many cases. Multiple methods were employed for the determination of yield points which form yield surfaces. Comparisons between several results have been made. Our FEA results, Zhang's function and Gibson's theory show good agreements except some differences under hydrostatic loading. A conclusion can be made: besides the void fraction and the yield strength of the wall material, the structure of foams also has a significant effect on the yield behavior of foams. Yield surfaces normalized by the uniaxial tensile strength of foams are more reasonable.