A continuum damage mechanics approach for fretting fatigue under out of phase loading

- Continuum damage mechanics (CDM) approach.
- Critical plane (CP) approach.
- Out of phase loading conditions in fretting fatigue.
- Comparison between CDM and CP.

The phenomenon of fretting fatigue involves multiaxial stress states near the contact interface and is mainly characterized by nucleation and propagation phases. Based on the mechanism of each phase, various approaches have been developed to predict damage initiation location and life. This paper aims to investigate the effectiveness of continuum damage mechanics (CDM) approach under in phase and 90° out of phase loading. Two cases with different material and loading conditions are considered for this analysis. The first case includes constant normal load and phase difference is generated between axial cyclic stress and tangential load. Whereas in the second case, cyclic normal load is applied and phase difference is generated between normal load and other two loads i.e. cyclic axial stress and tangential load. The results obtained using CDM approach are compared to those obtained using critical plane (CP) approach. The numerical results are also compared with experimental results from literature. It is observed that, both approaches provide good estimate of initiation location and life for in phase loading. With phase difference of 90°, the initiation locations also match well with the experimental results, however, for life estimation CDM approach has shown better prediction than CP approach, especially at lower loads. In addition, both approaches have shown that with phase difference of 90°, the fretting fatigue life increases as compared to in phase loading.