A New Model of Fatigue Crack Growth Rate Considering Mean Stress Effects Due to Locked-In Stress

During the fabrication of large structures, proper consideration of the mean stress due to locked-in stress is very important to quality control. In general, crack propagation life is shortened when applying the tensile mean stress. In this study, we examine the mean stress effect in terms of the fatigue crack growth rate (FCGR). We propose a FCGR model that considers crack closure, partial crack closure and compressive loads. The proposed model is validated with aluminum 5083 as well as three other materials at various stress ratios, and is compared with other existing FCGR models. We show that the proposed model effectively characterizes the FCGR under various stress ratios into a single line.