A 3D FEM methodology for simulating the impact in rock-drilling hammers

A three-dimensional (3D) finite element approach for modeling impact as it occurs in impact tools used in rock drilling is presented. The model permits one to simulate the energy transmission to the rock, the bit-rock interaction, and the process of rock fragmentation, all of which are important in the study and evaluation of such tools. The finite elements method (FEM) analysis allows one to simulate the impact in 3D stress-strain problems, to consider linear material properties, and to include post failure fracture propagation. Anisotropic elements have been used to model the rock post failure behavior. Infinite domain elements have been used to characterize boundary conditions far away from bit-rock interaction. The accuracy of the model has been evaluated both theoretically by comparing the result to those obtained with a model based on impulse-momentum principle as well as experimentally.