Using Cyclic Mean Stress Relaxation Data to Predict Residual Stress Changes Fatigue Loading

A method for predicting the cyclic fatigue induced residual stress(RS) relaxation is proposed. Specifically, with reference to a new on-line data base for cyclic mean stress relaxation results, the key variable of fatigue "hot-spot" stress-strain hysteresis loop width (plastic strain) is estimated and used to predict the rate of expected residual stress relaxation. In the paper the similarities of the stress-strain state denoted by a measured RS, when compared to the residuals induced and followed during a cyclic mean stress relaxation fatigue test, are discussed. Examples of the expected behavior of RS states during primarily elastic fatigue loading and during plasticity at the fatigue hot spot are depicted for cold work induced RS. Finally the RS behavior of both a carburized steel case induced RS and a welded steel induced RS are documented.