Multiphysics Coupling Analysis of HVDC Submarine Cable Joints Considering Dynamic Thermal Contact Resistance at the XLPE-SiR Interface

The cross-linked polyethylene (XLPE) and silicone rubber (SiR) interface in prefabricated high-voltage direct current (HVDC) submarine cable joints is a critical weak point for thermal-electrical reliability. Conventional finite-element models often assume ideal thermal contact, thereby neglecting the dynamic evolution of thermal contact resistance (TCR) during operation. A steady-state thermal-resistance platform is used to characterize TCR over 0.11-1.0 MPa and 30-70 °C. The results show that, at elevated temperature and pressure, silicone grease laterally migrates (“squeeze-out”), leading to a non-monotonic TCR rebound. Accordingly, a dynamic TCR model is developed by augmenting contact-mechanics behavior with a rheology-based correction; parametersnandmquantify asperity deformation and grease extrusion, respectively. The model is then implemented as a thermal boundary condition in electro-thermal-mechanical multiphysics simulations. Considering dynamic TCR yields an interfacial temperature jump up to 9.6 °C under overload, increasing the conductor temperature relative to the ideal-contact case. Although the DC field redistribution is moderate, the temperature-driven reduction in breakdown strength markedly decreases the insulation safety margin (K), to 1/11 of that predicted by the ideal-contact assumption. The results highlight the importance of dynamic TCR in reliability assessment and offer guidance for insulation design and maintenance of HVDC accessories.