3D Finite Element Modelling of Fracture of Sand Particles Subjected to High Strain Loading Rate

Fracture is a common failure mode of sand particles when they are subjected to high strain rate (HSR) loading conditions such as blast, impact, or projectile penetration. The constitutive behavior and the failure mode of sand particles are influenced by the loading rate; therefore, a particle-scale constitutive model is necessary to address the effects of HSR loading and particle fracture within a sandy material. To that end, a Kolsky test (i.e., a HSR 1D compression test), 3D X-ray computed tomography (CT), and finite element methods were employed in this study to investigate the failure mode of individual natural sand particles when they are subjected to a HSR loading. Individual particles were first imaged using CT technique followed by testing them using Kolsky bar at an approximate strain rate of 104S-1. The fragments of fractured particles were collected and imaged using synchrotron micro computed tomography (SMT) for further evaluation of the fracture mechanisms within individual particles. A brittle fracture model was adopted to perform 3D Finite element (FE) modelling to capture the fracture of individual sand particles. 3D CT images of the particles were used to generate 3D meshes with similar morphology as the actual sand particles and the particles were loaded similar to Kolsky experiments. The paper discusses the calibration and the validation of the model and compares the fracture mechanisms within the sand particles based on FE simulations with experimental measurements. The brittle fracture model successfully simulated the fracture mechanisms of the experiments. The effect of loading mechanisms on the mechanisms of the fracture of the particles is discussed in detail.