Investigating rock particle breakage using 3D coupled peridynamics-discrete element method: Emphasis on local surface features

Individual particle breakage within rock-based granular medium profoundly influences the overall macro-scale behavior of the assembly, with the strength being notably impacted by particle morphology and surficial features. However, the widely used numerical methods often oversimplify the realistic morphology, resulting in unrealistic particle breakage simulations. The current study addresses the limitation by specifically investigating the influence of local surface geometry on particle strength and breakage patterns. X-ray Computed Tomography (CT) images of particles were used to obtain the realistic geometry and Voronoi Parallel Linear Enumeration (VPLE), a morphology-preserving surface generation strategy was introduced to capture the complex surficial features. A coupled peridynamics-discrete element framework was proposed to simulate the breakage of individual rock based aggregates. The numerical framework was validated with Brazilian tests on basalt rock cores, and a rigorous comparison was made against other finite-discrete element methods. The study explores different extremes of particle morphology, considering the presence and absence of concavities in the breakage simulations. Robust computational geometry pipeline was employed to measure contact area and local radius of curvature during the breakage. The findings highlight that the concave features, along with the contact curvature significantly reduce the particle strength ($\approx 40\text{\%}$) as opposed to the convex particle variants exhibiting higher strength. The presence of sharp surficial features led to multiple failure mechanisms, including initial asperity crushing and subsequent splitting failure. The present work strongly emphasizes the importance of considering realistic particle geometry in numerical simulations of granular materials undergoing crushing.