Study on the Yield Behavior of Closed-Cell Foams under Multiaxial Loads Based on Different Yield Definitions

In this paper, the yield behavior of closed-cell foams under multiaxial load conditions is investigated via finite element analysis on the representative volume element (RVE) scale by using the regular Kelvin of RVE and random models of RVE, respectively. Several different definitions of yield are considered in the study. By benchmarking the simulations with the experimental data in the literature, it is shown that the elastic energy criterion is shown to be suitable for the definition of the yield point of closed-cell foams under different stress states. Based on the micro-scale elastic energy, which can be readily obtained by numerical simulation, a general yield definition is proposed to determine the yield behavior of the closed-cell foam materials at macroscopic scales. To test the adaptability of this general yield definition, we analyze multiple random models with different relative densities and inner structures. The results indicate that this general yield definition method can be used for different models, even applied to continuum materials.