Test MethodA methodology for assessing fatigue degradation of joined fibre-reinforced polymer composite tubes

Advantageous properties of fibre-reinforced polymer composites, such as high corrosion resistance, may lead to enhanced performance of structures compared to those made from conventional engineering materials. For this reason, composite pipe has been the subject of various studies aimed at mitigating deficiencies that metallic components exhibit in corrosive environments. Using advanced winding techniques, composite tubes can be manufactured cost effectively with high quality. The joining of composite tube sections is best achieved using adhesive bonding. However, incomplete understanding of associated damage mechanisms hampers modelling and failure predictions. The present contribution is concerned with the fatigue damage evolution in joined composite tubes. It was observed from experiments with joined tube sections that two simultaneous damage mechanisms govern the damage evolution under fatigue loading, namely matrix cracking in the tube sections and debonding of the joint. A methodology is presented that allows for the individual quantification of damage in the joint and tube sections by means of a mechanical model. The effectiveness of this methodology is demonstrated employing results form an experimental study on adhesively bonded glass-fibre-reinforced epoxy polymer tubes.