Effect of Specimen Thickness on Fatigue Crack Growth Rate

摘要

Fatigue tests were performed on the compact tension (CT) specimens of Type 304 stainless steel and Inconel 718. The effects of specimen thickness on crack tip deformation and fatigue crack growth rate (FCGR) were investigated for specimens of different thicknesses. In the analysis, the elastic plastic fracture mechanics (EPFM) parameter known as the cyclic J-integral (triangle openJ), was adopted to observe the local plasticity at the crack tip. This was compared wit the linear elastic fracture mechanics (LEFM) parameter known as the stres sintensity facotr range (triangle openK). The results show that FCGR is a function of spedimen thickness, the effect of which is accelerated as specimen thickness increases. It is therefore concluded that specimen thickness which is not considered in ASTM E647 should also the taken into account in the measurement of FCGR.