Analytical prediction for lateral buckling of tensile wires in flexible pipes

The development of oil and gas fields in deepwater challenges the design of flexible pipes due to high pressures, temperatures and dynamic loads. Amongst the known failure modes, lateral buckling of tensile armor layers in flexible pipes has attracted extensive interest for its complicated mechanisms. The present paper addresses lateral buckling behavior of tensile armor wires in flexible pipes when armor annulus is flooded. Based on the thin curved beam theory, a single armor wire is modeled on a cylindrical surface without considering the effect of friction and bending through a system of six order nonlinear differential equations. Then, by applying a perturbation technique, analytical solutions are obtained which reveal a series of potential lateral buckling modes. An estimate for the lateral buckling is obtained under conditions given herein. Case studies are performed comparing the proposed model with the results obtained through a numerical program and alternative analytical model available in the literature.