Compression Testing with Equibiaxial Pre-strain for Loading Path Dependency Estimation of Low-density Porous Materials

Abstract

In this paper, the compression behavior of low-density porous materials is inspected to apply them to the various parts of machines like shock absorbing structures. The multiaxial behavior of the compression process should be observed for the application in addition to the fundamental uniaxial compression mechanics of the materials. Then equibiaxial pre-strained compression testing is adopted for the observation. Here, polyurethane form is targeted as testing material because of its simplicity in the mechanics of compression process. The results of uniaxial and pre-strained compression testings show that the pre-strain causes the hardening of the porous material, and the change of the hardness depends on the amount of total volume change. The parameter of cell disappearance rate, which is concerning with volume change, is used to formulate the multiaxial stress-strain relationship. The multiaxial behaviors of the experiments can be simulated by using the formulated equations, and these results also show the importance of volume change effect in the compression behavior.