Numerical Investigation on Mixed Mode (I-II) Fracture Propagation of CCBD Specimens Under Confining Pressure

Abstract

A new numerical method, verified by the analytical solution of the weight functions and experimental paths, is developed to evaluate the crack initiation and propagation generally in mixed mode (I-II). This numerical method combining the interaction integral method and the maximum tangential stress (MTS) criterion is based on the finite element method of secondary development. The influence of combined confining pressure and diametric forces on crack propagation trajectories for CCBD specimens are studied. It is indicated that the crack propagation direction independent of the confining pressure keeps the same with the line of original crack as the loading angle is equal to [Formula: see text]. But when the loading angle is greater than [Formula: see text], the curvature of the curve trajectory in the early stage of crack propagation increases with a larger confining pressure. Further, it is found that larger values of the loading angle and relative length will make the effect of confining pressure more significant at the early stage of crack growth.

Numerical Investigation on Crack Propagation for a Central Cracked Brazilian Disk Concerning Friction

“…There is a new contour C set outside the contour Γ, which makes the region S closed. Then, through the divergence theorem, the line integral of Equation (1) can be further written as below [19,27,31]…”

“…Because the selection of the stress intensity factors and T-stresses in the auxiliary fields is different for the interaction integral, the selection of auxiliary fields in this paper is consistent with that of the Refs. [19,[32][33][34].…”

“…If the SIFs of the auxiliary fields satisfy special conditions [19], the SIFs of the actual fields can be derived as…”

“…For instance, Hua et al [11,16] and Zhou et al [18] accurately calculated the stress intensity factors and T-stresses for CCBD under concentrated force and confining pressure through conventional finite element method (FEM). Huang et al [19] and Hou et al [20] calculated those fracture parameters under different confining pressure coefficients based on the improved finite element method. Furthermore, various methods were reported for the fracture propagation under complex conditions.…”

“…Moreover, there are few reports on fracture parameters and propagation of crack, considering the effect of friction for CCBD specimens through the general numerical methods. Therefore, prompted by an improved numerical method proposed by Huang et al [19], a modified finite element method (MFEM) is developed. The MFEM involving the behavior of the frictional contact is based on FEM using user defined subroutine.…”