A hybrid damage model for simulating adiabatic shear bands

Adiabatic shear band (ASB) is one of the most important failure modes under high strain-rate deformation. In this work, we propose a hybrid damage model to simulate ASB. The proposed model possesses the following features: (a) as the criterion both for initiation of shear localization and for transition to fracture, it utilizes the equivalent plastic strain (EPS), a quantity relatively easy to measure experimentally and memory-saving, and (b) it shows an exponential degradation of the flow stress with respect to the EPS after initiation of shear localization, in agreement with experiments. These two features are not simultaneously possessed by two prevalent models, namely, the EPS based damage model and the plastic strain energy based damage model, which indicates the potential advantage of the proposed model. The aforementioned three damage models are compared using two classical tests, i.e., the impact test of a hat-shaped specimen and the explosive compression test of a hollow cylinder, and the results show that the models give somewhat different results under the same setup and the damage criterion highly influences the predicted plastic strain evolution and fracture process.