Time-load testing of nonceramic insulators with fiberglass core rod-a 20 year summary

Time-Load (static fatigue) testing of fiberglass rods used in nonceramic insulators (NCIs) has been underway for over 20 years. Data collected over that time frame is reported in this paper for NCIs manufactured with 16 mm (5/8") diameter and 22 mm (7/8") diameter epoxy fiberglass rods. All of the samples tested utilized crimped steel end fittings for transference of the applied tensile load to the fiberglass rod and from the rod to the support structure. Samples with and without a polymer housing covering the core rod are included. The data includes time-load test results under constant load to failure and residual strength evaluations after the removal of a long-term time-load. The results indicate a very flat time-load curve under nominal conditions. The residual strength tests were unable to quantify any significant loss in strength as a result of long-term overload conditions.