抄録
Axles are one of the most important components in railway vehicle with regard to safety, since a fail-safe design is not available. Initiation of the fretting fatigue cracks at the press-fitted part of the railway axle still remains unsolved. Using 40-mm diameter axle assemblies, fretting fatigue tests were performed in order to clarify the effect of the understress, which is lower than the crack initiation limit under constant load, on crack initiation in two-step multiple loading test. Two-step multiple loading patterns consist of fretting fatigue limit under constant load based on the stress to initiate cracks σ_<wfl.mic> and a stress of half or one third of the σ_<wfl.mic>. It was found that the fretting fatigue cracks were initiated under variable loading condition even if a stress is not exceeding σ_<wfl.mic>.
