A coupled isogeometric/multi-sphere discrete element approach for the contact interaction between irregular particles and structures

An isogeometric/multi-sphere discrete-element coupling method is presented to model the contact or impact between structures and particles with complex shape. This coupling method takes advantages of the multi-sphere discrete element method for particles to provide the high computational efficiency and excellent robustness of their contact modelling. The advantage of isogeometric analysis (IGA) for continuous solid material, e.g. the exact geometric description, is also taken to achieve a more accurate contact interaction with an excellent time continuity. In the coupling procedure, the CGRID method is used for the global searching. The exact contact situation of the discrete element and the IGA element surface is further determined in the local searching by solving non-linear equations numerically. Then, the normal contact force between a sphere and an IGA element is calculated using a penalty based Hertz-Mindlin contact model, and damping and friction forces are also considered. Both the accuracy and validity of the coupling method are examined by comparing the numerical results of an example with one particle impacting on a quarter of a cylinder, with those of the FEM model where the particle is modelled as a rigid body. Two additional examples involving particles impacting onto a corrugated plate and particles of different shapes impacting on a chute, are simulated to further assess the applicability and robustness of the proposed method.