Automatic adaptive mesh upgrade schemes of the step-by-step incremental simulation for quasi-linear viscoplastic granular materials

A new approach is suggested for the generation of adaptive finite-element meshes applied in the step-by-step incremental simulation for compaction of quasi-linear viscoplastic granular materials. A contact detection algorithm is employed for accurately prediction of where and when a contact between particles occurs. On the basis of a mixed triangular and quadrilateral finite-element mesh system, a mesh upgrade scheme is generated to simply remesh the whole system after a contact is detected. By carefully monitoring the geometrical distortion of each quadrilateral element, a suggested concave element modification algorithm can be used to improve accuracy of the finite-element model. In addition, a locking prevention scheme is generated to prevent highly constrained situations during the viscoplastic analysis. Results of numerical experiments demonstrate efficiency of the mesh upgrade procedures used in the step-by-step incremental simulation. In fact, the proposed mesh re-generation schemes can easily be extended to many other cases without major modification.