The Crack Growth Resistance Curve as a Single-Parameter Representation of Stable Crack Propagation in Thin-Walled Structures

摘要

Tensile tests were done on center cracked specimens. The materials chosen were 7075-T6, 7475-T761 and 2024-T3 aluminum alloys. The specimens were L-T orientated with the thickness in all cases 2 mm. By systematic variation of the specimen width and the initial crack length, the effect of these parameters on the crack growth resistance curve (R-curve) was investigated. The R-curves of the specimens tested are a single-valued function of the stress intensity up to a limiting value of the net section stress that is equal to 0.9 times the yield strength. The crack length was measured simultaneously by the potential and the compliance method. The potential method yields less scatter than the compliance method. The potential based R-curves were then used to predict failure by the R-curve concept. The results of failure prediction for elastic-plastic behavior support a recommandation for a standard test method, using R-curve measurements.