Stress concentration testing of composite insulators with crimped end-fittings

In recent years, many studies on the mechanical properties of composite insulators using finite element analysis (FEA) techniques have been carried out. However, FEA is only an approximate method. In order to evaluate the actual mechanical stress on the surface of a fiber reinforced plastic (FRP) rod during the crimping and tensioning process, stress testing utilizing foil gauges were performed on the crimped insulator ends, subjected to compression or axial tensile loads. The mechanical strength effects of variations of axial strain of the rod surface, in the compression procedure, for various crimping conditions, were tested. The tested axial stress distribution along the axial FRP rod under various tensile loads was given, and the influence of different crimping conditions on stress concentration of the FRP rod was discussed. In addition, experimental testing results have been compared with the numerical data obtained by the FEA method.