Fracture Mechanics Parameter Computation Using Tetrahedral Finite Element with Drilling Degrees of Freedoms (Virtual Crack Closure-Integral Method for Generalized Tetrahedral Finite Element)

This paper presents a virtual crack closure-integral method (VCCM) for a generalized fournode tetrahedral finite element that has drilling nodal degrees of freedoms (DOFs) . The generalized tetrahedral finite element has superior accuracy over the liner tetrahedral element. VCCM computes the energy release rate and the stress intensity factor at the crack front. VCCM computes the fracture mechanics parameters accurately only from the nodal reaction forces and displacements. Furthermore, in mixed mode problem, it is easy to split energy release rate into each mode of crack deformation. In this paper, a VCCM formulation for the generalized tetrahedral finite element is developed for the case of mode I crack deformation. The contributions of nodal drilling DOFs on the computation of energy release rate are described in detail. Similar discussions can be extended to mixed mode problems. Finally, some numerical examples are presented and discussions on the accuracy of proposed VCCM are given.