The Influence of Contact Friction on the Breakage Behavior of Brittle Granular Materials using DEM

In this study, a numerical triaxial compression test was carried out to investigate the influence of contact friction on the breakage behavior of brittle granular materials using the 3D discrete element method. An commercial software named Particle Flow Code 3D (PFC3D) was applied to undertake these simulations. The cubic numerical model was 30mm wide, 30mm long, and 30mm high, and contained 562 crushable agglomerates. Each agglomerate was made of 57 uniform spheres bonding together by parallel bond and packing in the form of hexagonal close packing(HCP), then ten percent of spheres were randomly deleted to consider the effect of initial flaws. A new method based on Graph theory was developed to track the Particle Size Distribution (PSD) evolution during shearing. Four numerical models with different inter-particle friction coefficients μ ranging from 0.2 to 0.8 were tested and the particle breakage extent was quantified with the Hardin's breakage index and the ratio of broken parallel bond. The results showed that both Hardin's breakage index and the ratio of broken bond increased with an increase in the inter-particle contact friction coefficients. However, the frictional energy dissipation did not demonstrate the same trend. The mechanism of this discordance was discussed in this paper. keywords: contact friction, particle breakage, granular materials, DEM.