Fracture prediction of key-hole notched graphite plates by using the strain energy density based on the equivalent factor concept

In this research, the strain energy density criterion is modified to predict the fracture load in engineering components weakened by key-hole notches under tensile-shear mixed mode loading. This new approach is based on the equivalent mode І factor concept as presented in a new closed-form solution. In fact, the new proposed method is the governing idea of the equivalent local mode I concept, which has been formerly applied to U- and V-notches; but in this investigation the new equivalent factor is introduced in order to reduce the numerical analyses. Therefore, by applying the equivalent mode І factor, one can eliminate the large part of the energy section calculation to predict the fracture load of the notched specimens. To verify the validity of the presented new method, the theoretical predictions are compared with a large bulk of experimental data reported in the literature which obtained from the fracture tests on the key-hole notched graphite specimens. Finally, it is shown that new proposed model with a total discrepancy of about 6 % is an appropriate failure criterion.