Senior research engineer, Swiss Federal Labs, for Materials Testing and Research (EMPA), Duebendorf,
Pages: 13 Published: Jan 1999
The cut compliance method was developed to measure residual stress profiles. Its idea is to release them by introducing progressively a cut into the considered body. From the strain change due to progressive cutting it is possible to calculate the distribution of the released stresses. Since the method uses fracture mechanics principles the stress intensity factor due to residual stresses is delivered as well. Being a special type of residual stresses, the distribution of the contact stresses of fatigue crack closure and the corresponding closure stress intensity factors can be suitably determined by this method. Furthermore, it enables the residual stresses in front of the crack tip to be determined, which in crack retardation play a role as important as the closure effects. The basic theoretical relations for some frequently used fatigue specimens are analytically derived. They also can serve to evaluate the contact stresses from the commonly used unloading compliance technique, which is often used to identify crack closure effects. Some preliminary examples demonstrate the capability of the suggested method.
crack closure, closure stress intensity factor, experimental, influence functions, residual stress
Paper ID: STP15757S