Numerical Analysis of Cyclic Impact Damage Evolution of Rock Materials under Confining Pressure

To study the effect of cyclic impacts and confining pressure on the damage evolution of rock materials, numerical simulations of cyclic impact tests on rock materials under confining pressure were carried out by LS-DYNA using dynamic relaxation and full restart analysis. The static confining pressure was applied by dynamic relaxation, and cyclic impacts were realized by full restart analysis. As the crack generation and propagation result in the failure of elements in the finite element model, the damage variable defined by the crack density method was characterized by volume reduction. Numerical simulation indicates that both the confining pressure and amplitude of incident stress waves significantly affect the damage evolution of rock materials. High incident stress waves lead to severe damage, while large confining pressure results in minor damage. Under confining pressure, the damage to rock materials is alleviated due to the constraint effect on crack propagation. The number of cyclic impacts before macroscopic fracture increases as the confining pressure increases and decreases when the amplitude of the incident stress waves increases. The cumulative damage of rock materials under confining pressure progressively increases with the number of cyclic impacts, and the damage evolution exhibits three distinct stages: rapid rising, steady development, and sharp rising.

Automated summary

Numerical simulations using LS-DYNA were performed to study the effect of cyclic impacts and confining pressure on the damage evolution of rock materials. The results show that both the confining pressure and amplitude of incident stress waves significantly influence the damage evolution. High incident stress waves result in severe damage, while large confining pressure leads to minor damage. The damage to rock materials is alleviated under confining pressure due to the constraint effect on crack propagation. The cumulative damage of rock materials under confining pressure progressively increases with the number of cyclic impacts, exhibiting three distinct stages of evolution: rapid rising, steady development, and sharp rising.