Numerical modelling of the structural behaviour of thin-walled cast magnesium components

Abstract

Axial crushing, 3-point bending and 4-point bending tests have been performed in order to establish an experimental database of the behaviour of generic high pressure die cast (HPDC) AM60 structural components. In this paper, the experimental data are applied to obtain a validated methodology for finite element modelling of thin-walled cast components subjected to quasi-static loading. The HPDC structural components are modelled in LS-DYNA using shell elements. The cast magnesium alloy is modelled using both the classical J2-flow theory and an elastic–plastic model based on a non-associated J2-flow theory. In the latter, the constitutive model includes the Cockcroft–Latham fracture criterion, which is coupled with an element erosion algorithm available in LS-DYNA. It is further possible to define the fracture criterion as a Gauss-distributed stochastic parameter to allow for heterogeneities in the cast material. The constitutive model and fracture criterion are calibrated with data from tension and compression tests. Comparison of experimental and predicted behaviour of HPDC components gives promising results. It is found that the strength difference between uniaxial compression and tension has little influence on the numerical simulations. The fracture criterion of Cockcroft and Latham seems to be an effective approach to predict failure in HPDC components.