Extension of a dynamic constitutive model to rock: validation with granite

The dynamic response and fracture of rock materials under high-rate and impact loading conditions are long-standing and critical issues in geotechnical engineering, impact dynamics, and protective engineering. Accurate constitutive modeling of rocks remains challenging due to the complex coupling among pressure dependence, strain-rate effects, damage evolution. In this study, a dynamic constitutive model integrated with an equation of state, originally developed for concrete-like materials, is extended to rock materials and validated using granite as a representative example. Triaxial compression tests were conducted using the RMT-301 rock mechanics testing system to systematically investigate the mechanical behavior of granite under varying confining pressures. The model parameters were determined based on a comprehensive experimental dataset, encompassing static triaxial compression tests, split Hopkinson pressure bar (SHPB) tests, split Hopkinson tension bar (SHTB) tests, and planar impact experiments. A user-defined material subroutine (VUMAT) was developed and implemented in the ABAQUS/Explicit finite element framework to simulate the mechanical response of granite under static triaxial loading, planar impact, and projectile penetration conditions. The results demonstrate that the proposed model accurately captures the stress-strain behavior of granite under different confining pressures, the particle velocity-time history, wave-structure evolution and Hugoniot elastic limit (HEL) under plate impact, and effectively predicts the penetration depth and failure morphology observed in projectile penetration tests. These results verify the reliability and robustness of the proposed model in capturing the dynamic response characteristics of granite over a broad range of impact conditions.