SHEAR INTERACTION AND TRANSVERSE BUCKLING OF TENSILE ARMOURS IN FLEXIBLE PIPES

The present paper addresses aspects of stresses, relative sliding and buckling in tensile armour layers of flexible pipes. Analytical models for torsion and curvature due to both axisymmetric loads and bending are presented. A shear interaction model is further formulated that allows for including the effect of shear deformations in the plastic layers and the model performance is investigated with respect to two full-scale experiments. A simple analytical model for non constrained transverse tensile armour buckling is formulated and compared to laboratory test data. Numerical studies are carried out to investigate the validity range of the torsion and curvature both due to axisymmetric and bending loads. In the former case two different computer codes are applied together with results published by others to validate the model. In the latter case, models including friction interaction between layers and the effect of cyclic bending is used to investigate the performance of the analytical models.