Mesoscale Contact Characteristics of XLPE–SiR Interface Based on Hyperelastic Constitutive Relation Analysis

The contact characteristics of insulation interfaces in cable accessories are critical in determining the insulation level of cable accessories. In this article, a mesoscale contact characteristic analysis model for the cross-linked polyethylene (XLPE)–silicone rubber (SiR) interface was established based on the hyperelasticity constitutive relation and the equivalent roughness principle. Micro-computed tomography (Micro-CT) was used to observe the cavity distribution of the internal contact interface of an actual XLPE–SiR interface sample, verifying the accuracy of the analytical model. Then, based on this model, the influences of external factors, including surface roughness and contact pressure, on the internal contact characteristics, such as actual contact area ratio, cavity size, and local contact stress distribution, were studied. It was found that the actual contact area ratio at the XLPE–SiR interface decreases exponentially with increasing roughness and increases linearly with increasing interface pressure. The local contact stress exhibits a nonuniform distribution, with the proportions of weak, average, and strong contact points approximately at a 1:3:1 ratio. This model offers a feasible approach for exploring the contact characteristics and insulation properties of the XLPE–SiR interface at a mesoscale.