Burst strength and impact performance on glass fibre reinforced epoxy (GRE) composite pipes

Abstract

While in service environment, the changes in the degradation mechanisms of the GRE composite pipes may occur in the matrix, fibre, and the fibre-matrix interfacial regions due to water diffusion. These composite pipes may also be subjected to impact loads, during manufacturing, installation or while in service. This research involves an experimental investigation of the deformation and failure on unaged and aged GRE composite pipes through the impact loadings and monotonic burst tests. Pipes were aged in tap water temperature at 80°C for periods of 500, 1000 and 1500 h in order to simulate in service environments, while trying to obtain reliable results from accelerated laboratory tests. At the end of ageing condition period, the pipes were impacted at room temperature for three different energy levels, which are 5 J, 7.5 J and 10 J before subjected to monotonic burst tests. The hyperbolic tangent model produced better predictions of moisture diffusion rate to the experimental results. From the experimental results and mathematical analysis, it was evident that the modulus of GRE pipes were significantly degraded (27% in axial and 15% in hoop direction) due to water diffusion. The results indicated that as the impact energy increase the peak force, displacement and absorbed energy also increased. The increased absorbed energy signifies that more energy was consumed in damage growth of the pipes. The impacted pipes have been subjected to moisture absorption content above 1% yielded lower burst strength and the ratio of the residual burst strength also reduced rapidly by about 50%. Weepage and eruption failures were observed depending on the applied impact energies.