Parameter sensitivity analysis on the buckling failure modes of tensile armor layers of flexible pipe

Abstract

Unbonded flexible pipes have become widely employed in marine environments with the development of the offshore oil and gas exploration industry. Such pipes are subject to complex loads, which may lead to significant failure. Tensile armor layers are key components of these flexible pipes, and radial buckling failure may occur under high compressive or other combined loads. In this paper, a simplified numerical model of the flexible pipe is developed using the finite element (FE) method, and the main failure modes of the tensile armor layers are simulated. This simplified model is an improvement over those employed in previous studies on tensile armor failure. Several parameters that have important effects on pipe stiffness are investigated. The results show that an increase in the winding angle of the tensile armor wires as well as the damage to the outer sheath of the flexible pipe will decrease the compressive stiffness significantly. The presence of friction between adjacent layers will increase the stiffness to a small extent while the external hydrostatic pressure enhances its axial stiffness greatly and improve the stability of the pipe. These results may be used as a reference in the development and engineering applications of flexible pipes.