Abstract
Particles slide and roll on each other when a granular medium is sheared. Consequently, the tribological properties, such as inter-particle friction and adhesion, play a major role in influencing their bulk failure and rheology. Although the influence of roughness on adhesion and friction of contacting surfaces is known, the incorporation of the surface roughness in the numerical modelling of granular materials has received little attention. In this study, the boundary element method (BEM), which is widely used for simulating the mechanics of interacting surfaces, is coupled with discrete element method (DEM) and the bulk deformation of granular materials is analysed. A BEM code, developed in-house, is employed to calculate the normal force–displacement behaviour for rough contact deformations, based on which a contact model is proposed. This is an efficient and relatively fast method of calculating the contact mechanics of rough surfaces. The resulting model is then implemented in the simulations by DEM to determine the effect of micro-scale surface roughness on the bulk compression of granular materials. This study highlights the importance of the effect of surface characteristics on contact behaviour of particles for the case of shallow footing and provides an efficient approach for modelling the flow behaviour of a large number of rough particles.
Highlights
The mechanical behaviour of granular materials originates from force transmission at inter-particle contacts [18]
In Eq 2, r is the rigid body movement of two rough surfaces in the normal direction, Z2 and Z1 are the surface profiles of the two rough particles, FN is the total applied load in the normal direction, H is the hardness of the softer material in contact, Ac is the area of contact and N is the total number of nodes in the domain of study
A novel approach for accounting elasto-plastic deformation of rough surface is presented by coupling boundary element method (BEM) derived contact behaviour and discrete element method (DEM) modelling for predicting bulk compression behaviour of a penetrating footing
Summary
The mechanical behaviour of granular materials originates from force transmission at inter-particle contacts [18]. The works so far can be categorised into two groups: direct geometry refinement, and contact model enhancement [1, 12, 23, 31, 32] In the former case, direct inclusion of roughness in DEM modelling has been carried out by assuming that asperities are small spheres, which are bonded to the main particles. This methodology is computationally expensive and restricted to surface roughness with a spherical shape [12, 31].
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