Journal ArticleDOI
Stochastic Response of a Tension Leg Platform to Viscous Drift Forces
M. G. Donley,Pol D. Spanos +1 more
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TLDR
In this paper, an equivalent stochastic quadratisation method is proposed, in which the drag force nonlinearity is replaced by an equivalent quadratic non-linearity.Abstract:
A stochastic analysis of a tension leg platform subject to wave and current loads is performed. The viscous force is modelled by the nonlinear Morison equation drag force term. As an improvement to equivalent stochastic linearisation of the drag force, and equivalent stochastic linearisation of the drag force, an equivalent stochastic "quadratisation" method is proposed, in which the drag force nonlinearity is replaced by an "equivalent" quadratic nonlinearity. The resulting nonlinear equivalent system is in a form which can be solved approximately by a Volterra series expansion. The non-Gaussian probability distribution of the response is approximated by a Gram-Charlier expansion. The method is applied on a three degree-of-freedom model. The power spectrum of the response determined by the proposed method compares well with the one obtained by Monte-Carlo simulation.read more
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Journal ArticleDOI
Modeling Nonlinear Systems by Volterra Series
Luigi Carassale,Ahsan Kareem +1 more
TL;DR: In this paper, an alternative technique for the evaluation of VFRFs is presented with the goal of simplifying and possibly automating the evaluation process, based on first representing the given system by an assemblage of simple operators for which VFRs are readily available, and subsequently constructing VFRF of the t...
Journal ArticleDOI
Equivalent Statistical Quadratization and Cubicization for Nonlinear Systems
TL;DR: In this paper, the authors developed two techniques for handling system and excitation nonlinearities: equivalent statistical quadratization and equivalent statistical cubicization, which may be employed to approximate it by a quadratic or cubic polynomial.
Journal ArticleDOI
Volterra models of ocean structures : extreme and fatigue reliability
TL;DR: In this paper, a new method is developed to estimate the reliability of nonlinear structural systems, modeled with second-order Volterra series, against both extreme and fatigue failures, including nonlinear response effects for a given input spectrum as well as long-term variations in the parameters of this input spectrum.
Journal ArticleDOI
Coupled Analysis of a Spar Structure: Monte Carlo and Statistical Linearization Solutions
TL;DR: In this article, the response of a combined dynamic system consisting of a Spar, a mooring line system, and top tension risers is presented, where the top tension of a riser is provided by a buoyancy can that is laterally supported by a preloaded compliant guide.
Journal ArticleDOI
Surge response statistics of tension leg platforms under wind and wave loads: a statistical quadratization approach
TL;DR: In this article, a method of equivalent statistical quadratization is proposed, whereby a statistically asymmetric nonlinearity in the forcing of a tension leg platform (TLP) is cast in a quadratic form.