Parametric instability prediction in a top-tensioned riser in irregular waves

Nonlinear vibration modes of an offshore articulated tower

“…However, two major problems arise, as stated by Bulian et al (2004), when dealing with parametric resonance in a stochastic environment: the determination of the stability threshold and the evaluation of the statistical properties of the process when stability limits have been exceeded. Many different definitions of stochastic stability can be used making the analysis of the stability threshold more difficult than that when a deterministic excitation is addressed (Bulian et al, 2004;Bulian, 2005;Hashimoto, 2006;Yang et al, 2013). Recently Silva and Gonçalves (2015) proposed the use of Hermite-Chaos polynomials together with the Galerkin stochastic procedure to discretize the stochastic differential equation of motion in a set of deterministic differential equations and obtained the parametric instability boundaries of a non-deterministic system as the lower bound of the results considering uncertainties in a given parameter.…”

Long-term stochastic heave-induced dynamic buckling of a top-tensioned riser and its influence on the ultimate limit state reliability

“…A riser is held at its top end by a tensioning system, which keeps the riser's body under tension in order to avoid compressive loads; nevertheless, due to the floater's heave (vertical motion), the tension fluctuates with time, and lateral vibrations (dynamic buckling) can be excited. The unwanted consequence us such phenomenon is the riser's damage due to excessive stress which could lead to oil or gas spills with consequent pollution and economic loses (Yang et al, 2013). Moreover, it is known that the heave motions of floaters are responsible for bending and buckling conditions that can lead to fatigue damage of risers (Katifeoglou and Chatjigeorgiou, 2016).…”

“…Many studies have been devoted to the issue of parametric excitation of offshore structures in which a coefficient appears as function of time in the governing differential equation. Said studies have included the research about risers and cables (Chatjigeorgiou, 2004;Chatjigeorgiou andMavrakos, 2005, 2002;Franzini et al, 2015;Franzini and Mazzilli, 2016;Hsu, 1975;Kuiper et al, 2008;Lei et al, 2014;Park and Jung, 2002;Prado et al, 2014;Wang et al, 2015;Wu et al, 2016;Xiao and Yang, 2014;Yang et al, 2013;Yang and Xiao, 2014;Zhang and Tang, 2015), tethers for tension-leg platforms Park, 1995, 1991), submerged floating pipelines (Yang et al, 2017) and parametric rolling of ships (Pipchenko, 2009;Thomas et al, 2010).…”

“…The general approach to investigate the parametric excitation of risers and tethers is as follows: (1) First, the nonlinear governing equation of motion with a timedependent coefficient is derived. (2.a) Then the stability of the linear Mathieu's equation (for single-frequency excitation) (Chatjigeorgiou and Mavrakos, 2002;Hsu, 1975;Park and Jung, 2002;Park, 1995, 1991;Prado et al, 2014;Wang et al, 2015) or Hill's equation (for multi-frequency excitation) (Xiao and Yang, 2014;Yang et al, 2013) is analyzed via the Strutt's diagram, where the stability is estimated analytically. (2.b) Another alternative is to analyze the linearized system by means of the Floquet theory (Kuiper et al, 2008;Lei et al, 2014;Zhang and Tang, 2015).…”

On the probabilistic distribution of loads on a marine riser

“…Special attention has been paid to VIV; W. Chen et al ( , 2014 studied coupled floater motions and VIV; Gu et al (2013b) and Josefsson and Dalton (2010) focused on the development of analytical models to assess VIV; Ma and Spencer (2014), Wang and Xiao (2016), Xu and Cater (2016) and Park et al (2015) studied the use of helical strakes to suppress VIV, whilst Dai et al (2015) opted for the use of time-delay feedback controller. Riser parametric excitation has received plenty of attention; Kuiper et al (2008) and studied single frequency parametric excitation, and Yang et al (2016Yang et al ( , 2013 and Yang and Xiao (2014) studied multi-frequency parametric excitation. Furthermore, scholars have dealt with long-term distribution of loads.…”