Experimental and numerical study on press-fitted railway axles: Competition between fretting and plain fatigue

To investigate the competitive relationship between plain and fretting fatigue in press-fitted railway axles, the plain fatigue limit and fretting fatigue strength were tested, respectively, by changing the depth of the stress relief groove. Next, detailed information on fretting and plain fatigue, as well as on fretting wear, was gathered. Finally, an evaluation methodology integrating the finite element (FE) simulation with the Modified Wohler Curve Method (MWCM) was established to evaluate the damage in both fretting and plain fatigue scenarios. It was found that as the groove depth increased, the plain fatigue limit decreased while the fretting fatigue strength increased. The optimal groove depth, h(opt), that equalized the anti-fatigue capabilities of the groove and wheel seat, was affected by the number of test cycles. For this press-fitted railway axle, h(opt) was 0.2 mm < h(opt) < 0.4 mm for 10(7 )test cycles, and h(opt) > 0.6 mm for 10(8) cycles. The calculated critical local stress condition, sigma(Cri), required for initiating a crack, was 161.8 MPa, which almost agreed with the theoretical value. The calculated sigma MWCM values can be used to characterise the fretting and plain fatigue damage. The local stress condition for determining an optimal groove depth was: sigma(MWCM) in the wheel seat and groove root simultaneously reached sigma(Cri).

Automated summary

This study investigates the competitive relationship between fretting fatigue and plain fatigue in press-fitted railway axles. By changing the depth of the stress relief groove, the plain fatigue limit and fretting fatigue strength were tested. Detailed information was gathered, and an evaluation methodology integrating finite element simulation and the Modified Wohler Curve Method was established. The study concludes that the optimal groove depth, which balances the anti-fatigue capabilities, depends on the number of test cycles.