Measurement of the critical energy release rate GIIC for filament wound GRP pipes

An experimental procedure is described for measuring the critical energy release rate GIIC of filament wound pipes by making use of lateral indentation experiments on these pipes and correlating the dissipated energy to the delamination area. Factors that might influence the results of this procedure are discussed. Two pipes of different nominal thicknesses have been tested and their critical energy release rates measured. The values obtained from different specimens of the same type show good consistency. The thinner pipes tend to produce a lower critical energy release rate. The measured values have been used as part of the input data in a numerical simulation of the problem of indentation of the pipes, which involves large deformations and extensive damage. Excellent agreement has been demonstrated between the results and experimental data, which serves as a validation of the procedure proposed for estimating the critical energy release rate.