Mechanical behaviour of a granular solid and its contacting deformable structure under uni-axial compression - Part I: Joint DEM-FEM modelling and experimental validation

This paper proposes an exquisite confined compression experiment to validate a recently developed numerical method (Joint DEM-FEM approach). A uni-axial compression apparatus was designed to investigate the mechanical behaviour of a granular solid under vertical loading and the load transmission to the containing wall. This tester consists of an instrumented thin-walled circular cylinder, two platens, a commercial dynamic material test machine (MTS 810), a bottom load cell and twelve bi-axial strain gage rosettes. Experiments were conducted on polystyrene beads. The delicately-designed confined compression test provides abundant experimental data for proving the validity of the proposed modelling technique.The corresponding simulations were performed by the developed numerical approach with the linking of discrete element method (DEM) and finite element method (FEM). To attain a high level of quantitative validation, the important particle properties required for DEM simulation were not simply assumed but measured directly in laboratory tests. Characteristics of the compression system, such as load-displacement response, force transmission to boundary surfaces, lateral pressure ratio, bulk wall friction, and stress distribution in the cylindrical wall, were evaluated. A comparison between the numerical and experimental results was made and discussed in this paper. The majority of compared physical quantities show reasonable to good agreement, thus giving a convincingly quantitative validation for the developed Joint DEM-FEM modelling technique. This proposed linking methodology is shown to give plausible results and can be used as a first step to solve the particulate solid-structure interaction problems.