LAUSR

Abstract In this study, the problem of “what is the critical value of notch root radius ρ max 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 σ f and σ F 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 σ f with σ F , the admissible maximum notch root radius ρ max is investigated. Based on the investigation, it is found that when the notch root radius ρ is approximately 0.4 times smaller than d 0 m  =  2 / π ( K IC / σ C ) 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 > 4 d 0 m .