Material modelling for crash simulation of thin extruded aluminium sections

An accurate prediction of material failure and fracture is essential for a successful crash simulation. A computationally efficient shell modelling is indispensable when simulating large structures. This does not allow for a physically based Gurson fracture model. Many phenomenological fracture criteria were developed, which often challenge experimental material characterisation. In this paper, the description of material failure and fracture for the aluminium alloy EN AW-6082 is carried out with a minimum set of experimental tests. The yield function and the strain hardening function are evaluated with orthotropic tensile tests. In addition, flat shear specimens are tested giving another point on the yield surface. With the experimentally determined strain hardening and yield function, forming limits are calculated with a simulation model and are integrated into LS-DYNA (Livermore Software Technology Corporation LSTC, LS-DYNA Version 971, Revision R6.0.0) as Müschenborn and Sonne forming limit curve. Material fracture is described by the maximum shear stress criterion which is also calibrated with the flat shear specimens. Finally, the material model is verified with three-point bending tests of thin extruded sections showing good agreement between experimental and simulated force-displacement curves as well as in the fracture pattern.