THREE-DIMENSIONAL MODE SEPARATION TO OBTAIN STRESS INTENSITY FACTORS

摘要

For mixed-mode loading at a crack tip under small-scale yielding condition, mode Ⅰ, mode Ⅱ and mode in stress intensity factors control the crack propagation. This paper discusses three-dimensional mode separation to obtain the three stress intensity factors using the interaction integral approach. The 2D interaction integral approach to obtain mode Ⅰ and mode Ⅱ stress intensity factors is derived to 3D arbitrary crack configuration for mode Ⅰ, mode Ⅱ and mode HI stress intensity factors. The method is implemented in a finite .element code using domain integral method and numerical examples show good convergence for the domains around the crack tip. A complete solution for the three stress intensity factors is obtained for a bar with inclined crack face to the cross-section from numerical calculations. The solution for the bar is plotted into curves in terms of a set of non-dimensional parameters for practical engineering purpose. From the solution, mode mixity along the crack front and its implication to the direction of crack propagation is discussed.