Finite element analysis of AHS steel under dynamic loading using a micromechanical modelling

Abstract

Currently, advanced high strength (AHS) steel sheets have been increasingly used in the automotive structural parts, where improved crashworthiness and lightweight design are required at the same time. Such steel sheets provide an excellent combination between high strength and great energy absorption. Most AHS steels exhibit microstructures containing several phases and constituents with different morphologies and mechanical properties. In this work, the dual phase (DP) steel grade 780 was investigated under dynamic tensile loading by means of a finite element modelling on the micro-scale. A representative volume element (RVE) model was applied to take into account the effects of microstructure characteristics on the mechanical behaviour of steel sheets at high strain rates. For the RVE modelling, the Johnson-Cook constitutive model was applied to describe the stress-strain response, whereas the Johnson-Cook damage model and damage locus were employed for predicting failure development of each individual phases of examined steel. The RVE simulations were performed under varying strain rates and states of stress and the results were subsequently compared.