Numerical study on the ignition/detonation mechanism of explosives and the associated structural failure under thermo-mechanical stimuli

The vulnerability of munitions to accidental stimuli, such as mechanical impact and thermal cook-off, poses significant safety risks and necessitates an effective assessment framework for Insensitive Munitions (IM). However, accurately predicting the response of munitions remains challenging due to the intricate coupling of thermo–mechanical–chemical processes, which involve multiple ignition/detonation mechanisms and complex structural failure modes. In this work, we present a unified meshfree computational framework designed to evaluate munition insensitivity under diverse loading scenarios. This framework is built upon the Hot Optimal Transportation Meshfree (HOTM) method and is integrated with the Eigen-Erosion algorithm for fracture modeling. To overcome the limitations of traditional single-mechanism detonation models, we introduce a comprehensive formulation that couples pressure-dependent Ignition and Growth (IG) laws with temperature-dependent Arrhenius kinetic model. This hybrid approach enables accurate representation of competing ignition mechanisms—ranging from shock-induced detonation to thermally driven deflagration—as well as the subsequent large deformation, phase transition, and structure fracture driven by the expanding reaction products. The proposed framework is employed to simulations of slow cook-off and bullet impact, demonstrating its capability to reproduce the complex interactions between energetic loading and structural response, and thereby providing valuable insights for assessing the safety of ammunition during storage and transportation.