Structural response of a flexible pipe with damaged tensile armor wires under pure tension

• A FE model is used to study the response of a 6.0” flexible pipe under pure tension.
• Several wires of the outer and inner tensile armor layers are assumed to be broken.
• Results from experimental tests are used to validate the FE predictions.
• Axial forces are redistributed among the intact wires of the damaged tensile armor layers.
• High stress concentrations occur in the wires near the broken ones.

This article studies the structural response of a 6.0” flexible pipe under pure tension considering intact and damaged conditions. In the damaged condition, several wires of the tensile armor layers are assumed to be broken. A three-dimensional nonlinear finite element (FE) model devoted to analyze the local mechanical response of flexible pipes is employed in this study. This model is capable of representing each tensile armor wire and, therefore, localized defects, including total rupture, may be adequately represented. Results from experimental tests validate the FE predictions and indicate a reduction in the axial stiffness of the pipe, a non-uniform redistribution of forces among the remaining intact wires of the damaged tensile armor layers and high stress concentrations in the wires near the broken ones. Moreover, the FE model indicates that significant normal bending stresses may arise in the pressure armor and inner carcass due to an uneven pressure distribution on these layers. Finally, the results obtained are employed to estimate the pull out capacity of the studied flexible pipe.