Numerical estimation of fretting fatigue life of bolted joints using continuum damage mechanics and SEAM Tool

Abstract

For fretting fatigue, micro-slipping often causes initial micro-cracks in the contact surfaces, which gradually propagate and eventually result in fracture failure. However, it is difficult to directly observe and measure the crack initiation and propagation processes of single-lap bolted joints due to the obstacle of testing technique. Therefore, this article presents an elastic analysis–based method, in which the total fretting fatigue lifetime is divided into initiation life predicted by continuum damage mechanics and propagation life calculated by SEAM Tool in combination with Paris’s law. Since the initiation life model implicitly reflects the result of damage process, one can directly calculate the initiation life based on the elastic stress analysis. The predicted fretting fatigue life, initial crack location, and propagation path are in reasonable agreement with the fretting fatigue test and scanning electron microscope observation results. In addition, it is found that among the main factors affecting fretting fatigue of steel single-lap bolted joints, the initial life is affected by cyclic stress, friction coefficient, and tightening torque, and the propagation path is mainly influenced by tightening torque.