Stochastic wave spectra estimation (SWSE) based on response surface methodology considering uncertainty in transfer functions of a ship

• Published in: Marine structures Vol. 90; p. 103423
• Main Authors: Chen, Xi, Takami, Tomoki, Oka, Masayoshi, Kawamura, Yasumi, Okada, Tetsuo
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.07.2023
• Subjects: Polynomial chaos expansion (PCE); Sea state estimation (SSE); Stochastic mean wave period; Stochastic significant wave height; Stochastic wave spectra estimation (SWSE); Uncertainty in transfer function; Stochastic wave spectra estimation (SWSE); Polynomial chaos expansion (PCE); Sea state estimation (SSE); Uncertainty in transfer function; Stochastic mean wave period; Stochastic significant wave height
• ISSN: 0951-8339; 1873-4170
• DOI: 10.1016/j.marstruc.2023.103423

In this paper, a new wave spectra estimation method is proposed in which the frequency domain wave estimation method (FDWE) is extended into a probabilistic analytical framework in order to estimate the encountered sea states involving uncertainty in transfer functions of a ship. The proposed method, named the Stochastic Wave Spectra Estimation (SWSE), makes use of an Hermite polynomial chaos expansion (PCE) to represent the uncertainty in the transfer functions and the response surfaces. The method involves a mathematical formulation where an extension of the deterministic FDWE concept to the space of random variables is made. The proposed method can accurately and easily estimate the encountered wave spectra based on ship response measurements accounting for uncertainty in the transfer functions. In this paper, numerical and experimental investigations of the proposed SWSE are made, where the uncertainties in the transfer functions of heave and pitch motions of a containership are taken into account. The validity of the SWSE is demonstrated by comparison to results of uncertainty analyses through the Monte-Carlo simulations (MCS). •The stochastic wave spectra estimation (SWSE) method in long-crested waves was proposed which is formulated by an Hermite polynomial chaos expansion (PCE).•The present SWSE offers the probability distribution of the wave parameters, i.e. significant wave height and mean wave period, based on the pre-defined uncertainties in the transfer functions of ship responses.•The uncertainties in H and T can be estimated by optimizing the stochastic objective function equations only once.•The validity of the SWSE is demonstrated by comparison to results of uncertainty analyses through the Monte-Carlo simulations (MCS).