With the continuous elevation in operating speed and traffic density of rail transit systems, dropper failures induced by high-frequency vibration and elevated stress levels have become increasingly prominent. However, field service data and mechanism-oriented studies on boltless integral droppers remain limited, leading to an inadequate understanding of their failure modes and underlying mechanisms. In this study, fatigue tests and finite element simulations were combined to investigate the failure characteristics and mechanism of boltless integral droppers. Fatigue tests show that the heart-shaped ring exhibited progressive wear-through at the contact interface with the wire clamp. Surface grooves, microscopic cracks, and cross-sectional delamination indicate that the damage process is governed by fatigue wear under repeated impact-sliding motion. A simplified finite element (FE) wear model based on Archard law was established to describe the material-removal component of this process. Under the investigated conditions, the model reproduced the same damage location and the same increasing trend of wear rate with tensile force as observed in the tests. Parametric studies show that higher tensile force and larger relative slip accelerate the wear of the heart-shaped ring. This study provides a feasible approach for wear simulation of boltless integral droppers and offers a useful basis for structural optimization and condition-oriented maintenance of railway catenary systems.
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