Fracture loads for blunt notches under mode I loading

In the present study, fracture load evaluation technique for blunt notches under mode I loading is investigated using the mean stress based line criterion. Considering the effect of notch root radius ρ, a new fracture evaluation method, applicable not only for the V-shaped notches but also for other notches such as shallow notches, is developed, For a large notch root radius ρ (i.e. ρ>ρ|_Cri-1), the notch fracture can be evaluated by a simple rule that the fracture occurs when the maximum stress σ_max reaches the material ultimate tensile strength σ_C. If ρ is large adequately such that ρ|_Cri-1>ρ>ρ|_Cri-2, the notch fracture is evaluated as the fracture problem of a circle hole in an infinite plate. Here, ρ|_Cri-1 and ρ|_Cri-2 are the critical values for ρ to satisfy the σ_max-alone condition and the ρ-alone condition, respectively. Moreover, as long as the V-notch condition is fulfilled by the notch geometry, the notch fracture under mode I loading can be treated as the fracture problem of V-shaped notches and evaluated by the generalized notch stress intensity factorK_I ^V,R or the maximum stress at the notch root σ_max. Whether the σ_max-alone condition, the ρ-alone condition or the V-notch condition is fulfilled is mainly determined by the ratio of the characteristic length d_0m to the geometric size of notched specimen.