Displacement Range Based Fatigue Strength Verification of KR-Type Rail Clip

Abstract

Because of recent enhancements to fatigue strength regulations in Korea, an analytical and experimental study was conducted to assess the fatigue performance of KR-type rail clips. Given the intricate shape and stress distribution of rail clips, accurately measuring stress at potential fatigue crack locations proves challenging. Hence, the finite and infinite life fatigue strengths of the rail clip were evaluated based on the displacement induced by train wheel passage, as opposed to stress. A test setup, capable of testing eight rail clips simultaneously, was developed. Fatigue tests across six displacement ranges from 1 to 4 mm identified a potential fatigue limit at a 2 mm displacement range for the KR-type rail clip. This proposed fatigue limit was analytically validated using the Smith–Watson–Topper method. Two distinct fatigue failure modes, consistent with finite element analysis findings, were observed. Additionally, a displacement range-based fatigue life equation, predicting a 5% probability of failure, was proposed.