Qingyuan Zhao

Corrosion failure was investigated in the aluminum alloy positioning sleeve of a limit positioner used on a coastal railway line. Field inspection, optical microscopy, scanning electron microscopy, energy-dispersive X-ray spectroscopy, and bulk chemical composition analysis were used to characterize the failed component. The sleeve exhibited layered exfoliation at the surface and blocky spalling in the central corroded region. Microscopic observations revealed intergranular cracking and separation of corrosion layers. Sulfur was detected in the analyzed regions, whereas chlorine was detected in one region. The measured Cu content was 2.08 wt%, exceeding the 0.10 wt% upper limit specified for 6082 aluminum alloy in GB/T 3190–2008. These findings suggest that the failure was associated with the coastal corrosive environment and the nonconforming alloy composition. Pitting, intergranular corrosion, and exfoliation were identified as relevant forms of damage, with sea breeze and train-induced airflow potentially promoting the detachment of loosened material. Material composition control, routine inspection, and suitable surface protection are recommended to reduce similar failures in catenary components.

In high-speed train traction power supply systems, compensation ropes serve as critical transmission components to ensure system stability. These ropes are specially designed as right-hand alternating lay wire ropes. During tension compensation of the contact wire, the compensation rope undergoes repeated bending around the ratchet device, making it susceptible to fatigue fracture. This study conducted bending fatigue tests on compensation ropes with complete structural configurations in accordance with GB/T 12347-2008. The stress distribution and deformation evolution induced by bending were simulated using the finite element method, enabling fatigue life prediction under cyclic bending conditions. Given the significant convergence difficulties encountered in large-deformation bending simulations of the full structural model, this study innovatively adopts Love’s elastic thin-rod theory as an alternative approach, which avoids the computational prohibitions of full-scale helical modeling while preserving critical bending stiffness characteristics. The results demonstrate that the equivalent elastic modulus derived from Love’s elastic thin-rod theory closely matches the modulus obtained through stress–strain curve fitting from strand tensile tests. Furthermore, under identical axial tensile loads, the equivalent diameter model and the full-structure finite element model exhibit nearly identical end elongations. The predicted bending fatigue life using the equivalent diameter model agrees well with experimental results, and the fatigue fracture mechanisms are further revealed through microscopic morphology analysis, collectively confirming that the proposed equivalent modeling strategy provides an efficient and reliable solution for fatigue life prediction of complex wire rope structures under coupled tension–bending conditions.