Research on Thermo-Mechanical Fatigue Properties of XL-ETFE Flexible Cable Insulation

To thoroughly investigate influence mechanism of cyclic loading and temperature on fatigue life of cross-linked ethylene-tetrafluoroethylene (XL-ETFE) flexible cable insulation, simulation framework was established through coupled solid mechanics, heat transfer, and fatigue life analysis modules with the COMSOL Multiphysics in the paper. Specialized multiphysics simulation model was developed for XL-ETFE insulated flexible cables in aerospace applications. Results revealed that as temperature increased from 298 K to 423 K, the peak thermal stress in XL-ETFE insulation rose by 26.76%, from 781 MPa to 990 MPa. Meanwhile, the maximum thermal deformation increased from 1060 μm to 1080 μm, showing a 1.89% growth, conclusively demonstrating substantial temperature dependence of mechanical properties. Furthermore, fatigue cycle number progressively decreased with reduced distance from mechanical constraints, reaching a minimum of 1650 cycles. Notably, when temperature escalated to 423 K, the minimum fatigue cycles declined to 1200, representing a 27.27% reduction. It demonstrated that thermal stress accumulation and mechanical constraints dominated fatigue failure. These findings could provide critical theoretical insights for optimizing the design of XL-ETFE insulated flexible cables in aerospace applications.