Optical observation and numerical simulation on the evolution of adiabatic shear band in structural steel

Adiabatic shear band (ASB) may cause damages and failures of many metal materials under impact loading, which is a key issue in the research of damage mechanism. The theoretical study is mainly focused on the relationship among the strain, stress, speed of shear and the initial flaw size in one-dimension shear conditions, which is used to determine the possibility of the generation of ASB. By experimental investigations, the features of ASB of titanium alloy, tungsten alloy and high-strength structural steel, including deformation fields, local temperature and the threshold value for ASB generating, can be detected. However, since there is little study on the real-time and in-situ measurements on the evolution process of ASB, the failure details according to the shear-localization are still unknown. In this paper, the real-time observations and visualizations on the evaluation of ASB in 45 steel under different impact conditions in SHPB are presented. The generating and evaluating processes in a single sample are detected and analyzed by a self-design optical system and the self-designed software, which is based on Digital Correlation method with high resolution. At the same time, the numerical simulations and micro-observations by SEM are obtained by LS-DYNA and the simulation results are in good agreement with the experimental ones.