Crashworthiness of aluminium extrusions: validation of numerical simulation, effect of mass ratio and impact velocity

Based on an experimental database obtained from static and dynamic tests on square aluminium extrusions in alloy AA6060 tempers T4 and T6, a numerical model using the LS-DYNA computer code was validated. Excellent predictions of the response of the tubes were found by using isotropic elasticity, the von Mises yield criterion, the associated flow rule and non-linear isotrop ic strain hardening. The plastic material parameters such as the initial yi eld stress and the strain hardening were determined from uniaxial tensile t ests. The geometry was modelled using shell elements and a small trigger in the extrusion side-wall represented the initial geometrical imperfections. The validated model was used to study the response of square aluminium tub es, varying the mass of the projectile and the impact velocity. The simulat ions showed that the mean load was an increasing function with respect to a n increase in the impact velocity and that the mass ratio between the proje ctile and specimen had no influence on this response parameter. (C) 1999 Pu blished by Elsevier Science Ltd. All rights reserved.