Experimental analysis and modelling of dynamic deformation and failure behaviour of steel

Institute of Automotive Lightweight Design, University of Siegen, 57076 Siegen, Germany

^* Corresponding author: chongyang.zeng@uni-siegen.de

Published online: 9 September 2021

Abstract

New specimen geometries with various stress states are designed and applied for dynamic loading tests. Oscillation-free force is measured during multiaxial loading tests in the strain range of 10^-4 – 10³ s^-1. The deformation and local strain fields of specimens have been measured using high-speed camera and evaluated by digital image correlation (DIC) techniques. It is found that the strain rate effects on fracture strain are stressstate dependent. To model the material plasticity and ductile fracture behaviour during dynamic tests, an extended damage mechanics model (eMBW model) is used. In this work, the model is enhanced and implemented into LS-DYNA. To cover the strain rate effects on plasticity at a large strain rate range, a modified Johnson–Cook-type rate-dependency and exponential temperature-dependency are used. In addition, the influences of both stress state and strain rate on fracture locus are considered. The enhanced damage mechanics model successfully predicts the deformation and fracture behaviour of the investigated steel under dynamic multiaxial loading.