Simulation study on mechanical properties of ultrahigh voltage insulation pull rod and its composite material structure

Insulation pull rod is an important component of SF₆ combined electrical equipment, which mainly plays the role of transmitting the mechanical load and insulation when the switch acts. To illustrate its failure mechanism, this paper considers the stability issue of cylindrical shells composed of anisotropic materials and employs finite element analysis (FEA) to model composite material tubes using a curved coordinate system. A model of aramid composite tube-type insulation pull rod was established to ensure its structural compliance with ultra-high voltage standards. Mechanical property simulations were conducted on the pull rod, Subsequently, the buckling characteristics of the pull rod under different end conditions were analysed. Finally, the multi-layer composite material tube was adopted to analyse the effect of the laying angle deviation of layers on buckling. The results show that the method using the curved coordinate system can effectively model and analyse anisotropic cylindrical tube materials. Under static load, the stress distribution on the rod is not uniform, with significant stress concentration at the junction of rod and metal joint. Different end connection condition has a great impact on the critical load for buckling instability. When both ends are fixed, the critical load is eleven times that of one end being fixed. The deviation of the primary material direction of the cladding from the axial direction in the rod results in a decrease in the critical load of buckling. When the laying angle deviation exceeds 3°, each additional degree of deviation decreases the critical buckling load by approximately 1.6%. This paper provides references for the stress characteristics and causes of damage in ultra-high voltage insulation pull rod.