A New CTOD Calculation Formula, Considering Strain-hardening Property

AbstractCrack opening profiles and crack tip opening displacement (CTOD) in single edge notch bend (SE(B)) specimens were investigated by the silicone rubber replication of loaded crack tips. Their measurements revealed that CTOD in BS7448 overestimated the actual CTOD for low yield-to-tensile ratio steel, and motivated to investigate a new CTOD calculation method, considering the variation of crack tip blunting behavior due to strain hardening. Supposing that CTOD45FEM, which was defined by the width between two intersections of ±45o lines from the crack tip and the numerical crack opening profile, was applied as CTOD, the calculation formula was then calibrated based on finite element analyses. The elastic term was decided with boundary layer model simulations. A geometric hinge rotation was examined, and a rotational factor, rp was newly calibrated. Furthermore, a new factor f, which was given as a function of the yield-to-tensile ratio of the material and the specimen thickness, was introduced to correct the plastic term. The appropriateness of the proposed CTOD calculation was verified numerically an