The importance of the fibre-matrix interface on the mechanical stability of composite insulators

An important aspect of the design of transmission line insulators is the mechanic answer to different loadings including highly dynamic cases like load transfer or ice drop. In the latter cases an assessment using force balances as per IEC 61109 is only limited in predicting the failure behaviour. The main reason is that this design method is not able to take into account the detailed damage state and accumulation of a given Glass Fibre Reinforced Plastic (GFRP) rod and especially the sharp stress increase at crack tips. Within this contribution typical examples of damage accumulation as well as mechanical fatigue are presented. Based on this description the basics of fracture mechanics are shortly explained. From its foundations in 1919 this method has been established as the preferred…