Dynamic response of deep-water catenary risers made of functionally graded materials

This paper examines the structural behavior of a steel catenary riser (SCR) with a segment composed of a functionally graded material (FGM) at the touchdown zone (TDZ). A co-rotational beam formulation is employed to evaluate the influence of material gradation on the static and dynamic nonlinear behavior of the riser. A finite element model is developed to predict the riser response considering environmental and operational conditions such as self-weight, buoyancy, current, soil contact, waves, buoys, and ship motion. Moreover, a comparison of SCR configurations is made between those constructed from FGM and those constructed from standard homogeneous materials. The study indicates that an SCR configuration with an incorporated FGM segment improves the curvatures near the TDZ, where designing to mitigate fatigue damage is critical.