切欠底に発生したモードIIIき裂のJ積分の簡便評価式

概要

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A J-estimation formula in the fully plastic regime was developed for mode III cracks emanating from notches. Power-law stress-strain relations were assumed. From examination of analytical stress and strain solutions of notches under longitudinal shear, it was found that the stress and strain distributions in the neighborhood of the notch root are approximately expressed as a function of the maximum shear stress τ_<max> (or the maximum shear strain γ_<max>) at the notch root and the notch root radius ρ, for nonlinear-hardening materials as well as for linear elastic materials. Based on this fact, the following J-estimation formula was proposed, which predicted the J-value of short cracks at notches : J=(π/2)(πn/2)^<(n-1)(2n-1)>τ_<max>γ_<max>c/(1+kc/ρ) where n is the strain-hardening exponent, c is the crack length, and k is a coefficient expressed as an increasing function of n. The accuracy of this formula was demonstrated by finite element J-integral analyses for elliptical notches with mode III cracks.
1986-05-25