Improvement of a Cycle J Integral for CT Specimens

Abstract

The cycle J integral formula for CT specimens has been improved as follows: ΔJ=(2/Bb)(α1 •U + α2 •ΔP•Δδ) + (2/Bb)Ue −1.2025a/w + 0.6233 for 0.3≤a/w≤0.53; ΔJ=(2/Bb)(α1 •U + α2 •ΔP•Δδ) + (2/Bb)Ue −0.02 sin[(π/0.23)(a/w−0.53)] for 0.53<a/w<0.95. This formula is applicable to the fatigue crack propagation range of 0.3≤a/w<0.95. In comparison with other formulae of the cycle J integral, the application range of the above expression is enlarged and its accuracy is also increased to a certain extent.