Effect of stress gradient and quadrant averaging on fretting fatigue crack initiation angle and life

摘要

Fretting fatigue involves multiaxial stress field due to presence of contact between two bodies. Near the contact edge, high stress gradient may be present depending on load and geometrical conditions. To account for high stress gradient or singular results, a regularization method may be required for better prediction of crack initiation angle and life. In the present work, conventional point and volume averaging methods are compared with a proposed quadrant averaging method to predict crack initiation angle and life. It is found that quadrant method produce more realistic results for initial crack orientation than other methods. Two multiaxial critical plane damage parameters, McDiarmid (MD) and Fatemi Socie (FS) are employed for this purpose. In addition, the influence of stress averaging on crack initiation life is analysed for two different geometries. It is observed that critical radius for stress averaging depends on stress gradient or rate of decay of damage parameter under the surface of the contact.