Abstract
A new technique, called “unloading elastic compliance method”, to detect the fatigue crack length as well as the crack closure behavior inside of the specimen by using strain gages has been developed.
The crack propagation rate and the crack closure behavior at a low stress intensity level were investigated on various kinds of materials using the above mentioned method, and it was shown that the crack propagation rate above the region of 10-5mm/cycle could be represented by the effective stress intensity range, ΔKeff. However, the crack closure behavior at the threshold level was found to be strongly dependent on the material properties.
