The admissible range of notch root radius for applying the singular stress field to its fracture analysis

In this study, the problem of “what is the critical value of notch root radius ρmax below which the fracture load of the notch with ρ≠0 can be evaluated by using the singular stress field for a sharp notch” is investigated analytically. Based on the existing fracture criteria, the ultimate loading stresses σf and σF are respectively calculated by using numerical analysis called body force method for the blunt notch and by using the singular stress field for the corresponding sharp notch. By comparing σf with σF, the admissible maximum notch root radius ρmax is investigated. Based on the investigation, it is found that when the notch root radius ρ is approximately 0.4 times smaller than d0m = 2/π(KIC/σC)2, the predictive error of the fracture load for the blunt notch(ρ≠0) by using the singular stress field for sharp notch (ρ=0) could be within ±5%. Here, the notch depth should be taken as large as t>4d0m.