Mechanical stress distribution in composite line insulators with crimped end fittings

Abstract:
The state-of-the-art in the production of composite line insulators is that the end fittings are crimped onto the fibre reinforced plastic (FRP) rod with a hydraulic press. Decisive for the quality of the crimping is to apply the optimum crimping pressure. The paper deals with the influence of the properties of the involved materials, in particular the influence of the properties of the metallic end fitting on the crimping process. The solution requires simulating the crimping process by using finite element analysis (FEA). For the calculation of the mechanical stresses, a model of the jaws, the end fitting and the rod was established. The material of the rod is modelled as orthotropic as the fibres are unidirectional. The steel of the end fitting was modelled multi-linear to reproduce its stress-elongation-behaviour. Based on the mechanical properties of the FRP rod and the metallic end fitting, the results of the simulation fit well to the real stresses in crimped end fittings. In conclusion, knowing the exact material parameters, it is possible to calculate the proper crimping stress for a given parameter set using a FEA.