A Thermo-Mechanical Smoothed Particle Hydrodynamics Framework for High-Speed Multimaterial Impacts

This study presents a coupled thermo-mechanical SPH framework for simulating high-speed multimaterial impacts involving large deformations. The framework consistently integrates reaction heat release, heat conduction, and temperature-dependent constitutive laws and equations of state into the governing equations, enabling accurate modeling of plastic flow, thermal response, and damage evolution. For metallic materials, the Johnson-Cook constitutive model and failure criterion are employed, while a friction- and viscosity-dominated post-failure response is introduced to represent mechanical behavior after melting and fragmentation. To address tensile instability in conventional SPH methods, a novel physically based pressure-limiting technique coupled with temperature evolution is developed. Furthermore, a dynamic particle activation strategy is proposed to efficiently resolve only the shock-affected regions, greatly enhancing computational efficiency. Numerical results show that the proposed framework can robustly capture interface evolution, temperature distribution, and failure patterns in high-speed multimaterial impacts. The findings highlight the crucial role of thermal effects in impact-induced damage processes. Overall, the developed model achieves high accuracy and stability under extreme strain-rate conditions, offering a reliable computational tool for investigating coupled thermal-mechanical behavior and damage mechanisms in high-speed impact events.