Study on the effect of particle morphology on single particle breakage using a combined finite-discrete element method

Particle morphology is an inherent characteristic that has a significant influence on breakage behaviors of natural sands. Based on X-ray micro-computed tomographic scanning and image-processing, the three-dimensional (3D) particle surfaces of natural sand particles were first reconstructed by the spherical harmonic (SH) analysis. The traditional morphological parameters of the particles, including sphericity, roundness, and aspect ratio were then calculated based on the SH-reconstructed particle surfaces. Furthermore, a 3D local roundness descriptor was used to characterize the local angularity of the contact area between a particle and its loading platens. To model particle breakage, this study developed a combined finite-discrete element method (FDEM) in which the cohesive interface elements were inserted between the finite elements to simulate solid fracture by defining a traction-separation damage law. By using the developed FDEM, a series of single particle crushing simulations were conducted for ellipsoid particles and two types of sand particles. The results show that the developed FDEM model is capable of simulating breakage behaviors of sand particles. Statistical analysis showed that local roundness is the most significant factor in determining the particle fracture pattern, with the strongest positive correlation with the particle crushing strength of sand particles subjected to uniaxial loading.