Evaluation of the brittle failure of blunt U-shaped notch under mode I loading

Abstract In the present study, the evaluation technique of fracture loads for blunt U-shaped notches is investigated using two fracture criteria, i.e. the mean stress based line criterion and the volume-based strain energy density (SED) criterion, and Filippi’s stress equation. It is found that under certain geometric conditions the fracture loads of blunt U-shaped notches can be evaluated by not only the generalized notch stress intensity factor K IC U , R , but also the maximum stress at the notch root σ maxC , and both the values of K IC U , R / K IC and σ maxC / σ C can be expressed by a function of ρ / ( K IC / σ C ) 2 . Two techniques are essentially equivalent. The geometric conditions can be estimated from the condition that the mean stress or the average SED over the control region in the actual specimens can be approximately evaluated by Filippi’s stress equation.