Composite fibre reinforced pipe elbows subject to combined loading

Abstract

Composite pipes are currently being used in a multitude of applications varying from civil to oil and gas applications. Pipes are generally connected together by means of pipe elbows that in turn are subjected to bending moment and pressure loading. This study looks into the effect of combined loading on the first ply and ultimate failure load of pipe elbows. The influence of pressure loading followed by a bending moment versus firstly applying bending moment followed by subsequent pressure loading, on the ultimate catastrophic failure, is investigated through numerical methods. The combined bending moment and pressure load ramping is also studied. Design by analysis finite element damage mechanics numerical methods are applied to investigate post first ply failure and stress redistribution. The study shows that different loading combinations can give rise to different damage mechanisms and ultimately failure loads. A safe design load envelope for a typical fibre-reinforced pipe elbow and following first ply failure and ultimate catastrophic is established and discussed.