Effect of subway speed and track irregularities on the fatigue life of e-type fastening clip under vehicle–track coupling dynamics

Vehicle–track coupling vibrations, primarily induced by track irregularities and vehicle speed, have a profound influence on the service life of fastening systems. However, the failure mechanism and damage evolution of elastic fasteners under such vibration coupling have remained elusive. In this research, tensile tests on 60Si2Mn steel and quasi-static as well as fatigue tests on e-type clips were conducted. A finite element model of the fastening system and a vehicle–track coupling dynamics model for a metro vehicle were developed to conduct a comprehensive analysis of the fatigue life of the e-type clip, considering the combined effects of track irregularity, vehicle speed and initial clamping force. Additionally, a modified mean stress correction model was employed to predict the clip’s fatigue life, and a novel two-parameter nonlinear fatigue cumulative damage model was proposed to describe the clip’s damage evolution. These innovative approaches and models provide valuable insights for guiding the installation and maintenance of track infrastructure.