Numerical Simulation of Mechanical Properties of Cellular Materials Using Computed Tomography Analysis

摘要

The IUPAC study "Structure and Properties of Linear and Cross-Linked Structural Polyvinylchloride Foams" (IUPAC no. 2003-038-4-400) of the IUPAC Subcommittee "Structure and Properties of Commercial Polymers" elucidates the mechanical properties of Polyvinylchloride foams. In order to predict the mechanical properties of polymer foams several simplified models were developed which take into account the density and stiffness of the bulk material,but do not apply any morphological information. Previous results on Polyvinylchloride foams indicate that the cubic model of Gibson and Ashby is not suitable to predict their compressive modulus. In this article,we discuss several alternatives for the prediction of the mechanical properties. In particular,a novel approach is presented in order to transfer cell morphological data obtained by computer tomography to realistic finite element meshes for numerical simulations. This approach allows to take into account the statistical character of the foam morphology and can be applied to predict the mechanical properties of foams. First,a computer tomography analysis was performed to determine the size distribution of the polymer foams using a nondestructive technique. The computer tomography information was applied to build finite element meshes using a tessellation of modified Kelvin cell units or truncated octahedra of various cell sizes. Then finite element simulations were performed using these meshes in order to predict the compressive behavior of polymer foams. The results of the numerical simulations were in a good agreement with those of experimental data. In conclusion,the mechanical properties of cellular polymers can be adequately predicted by taking into account the inhomogeneous foam structure,in particular the cell size distribution.