Parameter identification for open cell aluminium foams using inverse calculation

Abstract

Open cell metal foams are interesting lightweight materials, which are used in a variety of applications. Effected by the complex microstructure of open cell metal foams the macroscopic material behaviour cannot be described with a von Mises yield criterion. In comparison to bulk metals, open cell metal foams collapse under hydrostatic compression and tension. Modelling of this behaviour is realised by using a closed yield surface to describe the plastic behaviour. This contribution considers the asymmetric yield surfaces measured for open cell metal foams with 10 and 20 ppi. A Finite Element implementation of a single closed yield surface is introduced. Furthermore, a new approach to identify the material parameters of the yield surface as well as the structural Young’s and hardening moduli is introduced. The simulations are realised with a Finite Element Method and the numerical results are compared with the experiments. The numerical results are fitted to the experimental data by modifying the material parameters of the model in an iterative optimisation process. The optimised material parameters are used to describe different loading conditions for open cell aluminium foams. The results of the simulation are compared with the multiaxial experiments for the sake of validation.