AlSi7 metallic foams - Aspects of material modelling for crash analysis

Metallic foam samples of matrix alloy AlSi7 have been produced and mechanically tested under quasi-static and dynamic load. Model parameters for the Deshpande-Fleck and the ABAQUS 'crushable foam' material model were determined covering a density of 0.3-0.8 g/cm3. Yield surface determination uses uniaxial hydrostatic compression test results, extended by tensile test results for the latter model. Strain hardening was described on the basis of uniaxial compression by fitting a Rusch model to the experimental data, deriving its parameters as function of density. The predictive capabilities of the parameterised models were evaluated using experimental data gathered for load cases characterised by superimposed uniaxial and hydrostatic compression. Analyses show good agreement between simulation and experiment. Further uniaxial compression tests performed at varying strain rates over 4 orders of magnitude revealed no significant strain rate dependency of material properties and thus qualify the material model parameters determined for crash simulation.