Ratcheting Behaviour of Stainless Steel 316L with Interference Fitted Holes in Low-Cycle Fatigue Region

Abstract

This article aims to investigate ratcheting and mean stress relaxation in a steel holed plate with interference fit by using kinematic and isotropic hardening models. To predict the fatigue life of the plates, it was necessary to estimate the residual stresses, pre-stresses and ratcheting at the pin entrance and exit faces of the hole which were considered to be the potential location for crack initiations. Based on a three dimensional model, which considered the cyclic plastic behaviour of materials, the interference fit process of the pin into the hole was simulated. Four hardening models based on a strain-controlled pull–push test and unidirectional tension test were used to simulate the hardening behaviour of low-carbon stainless steel 316L. Ratcheting and stress relaxation in different planes through the plate thickness were examined. In order to study the effect of stress ratio on the ratcheting behaviour around the hole, four different conditions of cyclic loading with stress ratios of R = −1, −0.5, 0, 0.15 were investigated. The comparison between the analyses and available experimental results showed that the combined nonlinear kinematic hardening model with nonlinear isotropic model could provide more reasonable and more suitable responses for predicting fatigue life improvements with interference fit methods.