A coupled thermo-mechanical cohesive zone model for strain rate-dependent fracture of hat-shaped specimens under impact

Abstract

A coupled thermo-mechanical cohesive zone model for strain rate-dependent materials is proposed to illustrate the shear failure in the hat-shaped specimens made of U75V rail steel at various impact loads and temperatures.The cohesive energy and the maximum cohesive stress in the proposed cohesive zone model depend on strain rates and temperatures. The coefficients in the functions of cohesive energy, maximum cohesive stress, and the cohesive law are obtained through a combination of experimental and simulation data. The experimental strain waveforms are obtained by a split Hopkinson pressure bar system and the cohesive zone model is implemented using ABAQUS finite element software with the assistance of user subroutines.The findings substantiate the efficacy of the proposed cohesive zone model in accurately predicting the shear failure of hat-shaped specimens under high-speed impacts, as evidenced by the notable concurrence between experimental and computational outcomes within an acceptable margin of error. Notably, the cohesive energy and maximum cohesive stress in the model demonstrate a dual dependency on strain rates and thermal conditions, emphasizing the significance of considering both thermal and mechanical effects when simulating shear failure in materials experiencing high temperatures and high strain rates.