On the efficiency of the numerical evaluation of fracture parameters using a virtual strain gage method

A simple method, called the virtual strain gage method, is proposed for an accurate numerical evaluation of the stress intensity factor, the T-stress and the biaxiality parameter β. This method is based on the optimal positions of virtual strain gages located near a crack tip so that the effect of dominant singular strains are canceled. The applicability of the proposed method is examined for quasi-static and low-velocity impact loading conditions on an epoxy three-point bending specimen and PMMA single edge notched specimen. The effects of the loading conditions, the geometry configuration and the length of the crack were presented and discussed. A good agreement has been found between the results of the proposed method and those of the numerical and experimental data previously published. In addition, it is noticed that the proposed method is an alternative and more advantageous then the extrapolation method because of its simplicity and accurate results.