Fretting Wear and Fatigue Interaction Evolution of Bridge Suspender Wires under Various Contact Conditions and Cyclic Load Characteristics

Fretting fatigue is a critical failure mode in bridge cable systems, driven by the combined effects of localized contact conditions and cyclic stress. This study investigates the fretting fatigue wear evolution, fretting fatigue crack propagation, and fretting fatigue life for bridge suspender wires under different service conditions. Using a newly developed experimental apparatus for precise control of contact conditions and cyclic stress, the multiscale damage processes are characterized using an optical microscope, a scanning electron microscope and a three-dimensional scanning laser. Multiscale observations reveal that wear scar morphology evolves through distinct geometrical stages, with crack nucleation occurring preferentially at the scar edge where stress concentrations are most severe. The subsequent fatigue crack propagation is governed by cyclic slip mechanisms. A parametric analysis demonstrates that fatigue life exhibits a nonmonotonic dependence on contact angle and is significantly influenced by the interaction between contact angle and stress ratio. This study reveals the complex interaction between wear and fatigue processes and establishes a comprehensive understanding on how key service parameters govern the dominant failure modes. These insights are crucial for developing advanced life prediction methodologies and informing performance-based, antifatigue design strategies for critical components in long-span bridges.