A numerical investigation on critical plane orientation and initiation lifetimes in fretting fatigue under out of phase loading conditions

This study focuses on application of critical plane approach to in-phase and out-of-phase loading conditions in fretting fatigue problems. The efficacy of various multiaxial damage criteria is analysed to determine critical plane orientation and initiation life, and is investigated for the first time in case of out-of-phase loading condition. Furthermore, our study focuses on the estimation of initiation angle and initiation lives using multiaxial damage criteria. For analysis purpose, the damage criteria are categorized as stress-based (Findley parameter and McDiarmid criterion), strain-based (Brown-Miller criterion and Fatemi-Socie criterion) and virtual strain energy. based (Smith-Watson-Topper criterion and Liu 1 and 2 criteria). It is observed that shear stress and shear strain based criteria are able to predict both critical plane orientation and fretting fatigue lifetimes, whereas energy. based criteria, which employ normal stress and strain, are only suitable to predict initiation life. The deviation in estimation of initiation life for stress-based criteria is observed to be higher than others if the internal stresses are higher than yield stress. It is shown that initiation can occur on either of the preferred shearing plane depending upon material and loading conditions. The phase difference of 90 degrees and 180 degrees increases and decreases the initiation life respectively as compared to in-phase loading. In addition, 90 degrees phase difference introduces more shearing planes for damage nucleation.