抄録
The fatigue crack growth and the crack closure behaviors of a clad material were examined by using an explosively-bonded brass clad steel plate, in the case when the crack was propagated across the interface of the clad material. The apparent fatigue crack growth behavior of this material was complicated. Both acceleration and retardation were observed near the material interface. Corresponding to these crack growth behaviors, the extremely high and low values of the crack opening ratio, U, were observed. It was found that there was a poor correlation between the crack growth rate and the stress intensity factor range, ΔK. It was concluded that this was mainly due to the residual stresses which had been introduced in the material production process. A good correlation was found between the crack growth rate and the effective range of the stress intensity factor, ΔΔKeff. The result of the finite element analysis on the relation between the residual stress and the crack closure supported the conclusion that the observed complicated crack growth behavior of the clad material was caused by the residual stress.
