Fatigue testing and theoretical studies of two 4 in flexible pipes

The paper deals with fatigue testing, stress analysis, and fatigue modelling of two nonbonded 4 in inner diameter flexible pipe specimens. The pipes were exposed to different dynamic loading conditions until fatigue failure occurred in the tensile armouring layers. The primary failure modes were pure fatigue of both armouring layers for one specimen and fretting fatigue in the inner armouring layer for the other. Theoretical studies were carried out to investigate the correlation between the experimental failure modes and the conditions predicted by the fatigue model. Good correlation was found between the observed and theoretical behaviour.