Insights Into the Dynamic Fracturing Behaviours of Rocks Under Multiaxial Static and Dynamic Coupled Loads Through 3D FDEM With Various Contact Algorithms and Cohesive Zone Models

ABSTRACT Finite–discrete element method (FDEM) has become a widely recognised numerical method for simulating the fracturing behaviour of materials under various loading conditions. However, the substantial computational cost of three‐dimensional (3D) FDEM has led to a marked imbalance: extensive research exists on two‐dimensional (2D) FDEM, while studies on 3D FDEM remain limited. This study investigates the dynamic fracture behaviours of rocks under multiaxial static and dynamic coupled loads, utilising a self‐developed 3D FDEM parallelised based on a general‐purpose graphics processing unit (GPGPU). The 3D FDEM incorporates both intrinsic and extrinsic cohesive zone models (ICZM and ECZM) as well as various contact interaction algorithms to facilitate robust simulation of a full‐scale triaxial Hopkinson pressure bar (Tri‐HB) testing system. Dynamic uniaxial and biaxial compression (UC and BC) tests within the Tri‐HB framework are modelled with different combinations of cohesive zone models and contact algorithms, and the results are compared against each other and against laboratory experiments reported in the literature. The simulations demonstrate that the 3D FDEM with all these models and algorithms can reasonably capture the stress wave propagations in both metal bars and rocks as well as the primary dynamic fracturing behaviours of rocks under the coupled static and dynamic loads. However, computing accuracy and efficiency vary across model combinations. Overall, the 3D FDEM with the ECZM achieves the highest accuracy and efficiency.