Axial impact fracture and elastic–plastic deformation characteristics of the assembly of different numbers of spherical particles

To study the fracture characteristics of spherical particles assembly (SPA) under axial impact loading, impact experiments with different numbers of spherical particles are conducted. The propagation of fracture and strain evolution law of the SPA are investigated. Based on the experiments, contact model of the SPA under low-velocity axial impact is established. Firstly, the experimental results show that the stress concentration at the SPA contact forms a compression area, which is the easiest to fracture. The stress-induced cracks propagate along the normal direction of the compression area until the spherical particles fracture. Secondly, the strain variation exhibit obvious transition between spherical particles and the impact mechanisms leading to early fracture of the upper particles are further explored. Thirdly, contact model of the SPA under axial impact is established. The solutions of elastic and plastic deformation are obtained and verified by low-velocity impact experiments. The calculation examples and coefficient of restitution of the contact model are discussed. The results provide a reference for further analysis of failure mechanism of the SPA with axial impact loading.