Static and Dynamic Behavior of Highly Deformed Risers and Pipelines

Abstract

This paper models flexible risers and pipelines as slender elastica structures. The theoretical formulation leads to a type of nonlinear boundary value problem that can be solved numerically given appropriate boundary conditions. The offsetting effects of gravity and buoyancy are included in the analysis. These forces can provide considerable axial loading (as can thermal changes), and hence, stability (buckling) is a major concern. Initial studies are based on the planar problem. A free-vibration analysis is also conducted for small-amplitude oscillations about various deflected equilibrium configurations in terms of natural frequencies and corresponding mode shapes. Energy dissipation and fluid forces are key issues in the forced problem, especially when large deformations are involved. Free vibration information is a vital prerequisite in understanding the response of these types of structures in practice.

Instability of catenary-type flexible risers conveying fluid in subsea environments

“…These works have recently been extended to include static and dynamic analyses for various types of risers equipped with a buoyancy module. In particular, parametric studies to investigate the effect of design parameters such as external current and internal fluid speed on the equilibrium configurations of risers have been performed for a steep wave-type riser by Santillan et al (2010), and a lazy wave-type riser by Wang et al (2014) and Ruan et al (2014).…”

“…Most of the works we have discussed above, i.e., static and dynamic analysis of flexible risers, are based on numerical methods including the finite element method (e.g., Garrett (1982), Nordgren (1974), Chucheepsakul et al (2003), Chatjigeorgiou (2008), and Wang et al (2014)) or a finite difference method (e.g., Santillan et al (2010)) and are all well within the current capabilities of commercial riser design tools such as Orcaflex or Flexcom. Stability analysis, however, is not directly performed by these commercial packages.…”

A nonlinear mechanical model for deepwater steel lazy-wave riser transfer process during installation

“…14-16 show the configurations, tension and bending moment distributions for SLWR during recovery stage (steps [13][14][15][16][17][18][19]. The lower section extends, the TDP moves left, and the finial position of the TDP point is still at the right side of that at initial state SLWR1.…”

“…Li and Chau [17] modeled the suspended part of SLWR as three catenary segments, and focused on the study of dynamic responses which ignored the effect of bending stiffness. Santillan and Virgin [18,19] have presented a systematic study on the lazy-S and steep-S, steep-wave risers and did some experiments to validate the numerical results for varying configurations and conditions. Wang and Duan [20] obtained the numerical solutions of deepwater SLWR behavior based on the nonlinear large deflection theory and some factors are taken into the parametric analysis.…”

Non-linear Static Analysis of Offshore Steep Wave Riser

“…Santillan S.T. [6] put forward an elastic approach to describe the analysis of steep-wave flexible risers by a finite difference technique, and a free-vibration analysis was also conducted for small-amplitude oscillations.…”