Study on fretting fatigue crack initiation of scaled railway axles in consideration of fretting wear

Abstract

The objective of this study is to investigate the fretting fatigue crack initiation of press-fitted railway axles. Fretting fatigue tests were conducted on scaled railway axles, and the fretting wear and crack at the fretted zone were analyzed. Based on the test results, FE models which take the fretting wear profiles into account were established. And then, three multi-axial fatigue criteria combined with the theory of critical distance were used to evaluate the fretting fatigue crack initiation. The analysis results show that the contact pressure and slip amplitude within the fretted zone are increased with the evolution of fretting wear, and thus produce a gradual increment of frictional shear stress at the inner side of the fretted zone. This finally leads to the fretting fatigue crack initiation of press-fitted axles. The fretting wear would play a more significant role in fretting fatigue initiation of press-fitted axles in the condition of lower applied stresses and higher loading cycles. As compared with the SWT criterion based on the maximum normal stress and elastic strain amplitude, the criteria considering the shear stress as the main controlling parameter (modified Dang Van criterion and McDiarmid criterion) can give a better-predicted result of the fretting fatigue crack initiation for press-fitted axles.