Fatigue reliability of ship structures

VM Naval architecture. Shipbuilding. Marine engineering

Yu, Lei ; Das, Purnendu K.

University:University of Glasgow

Department:School of Engineering

关键词: Spectral fatigue,Structural reliability,Ship structures;   

Others  :  http://theses.gla.ac.uk/2259/1/2010YuPhD.pdf

来源: University of Glasgow

【 摘 要 】

Today we are sitting on a huge wealth of structural reliability theory but its application inship design and construction is far behind. Researchers and practitioners face a dauntingtask of dove-tailing the theoretical achievements into the established processes in theindustry. The research is aimed to create a computational framework to facilitate fatiguereliability of ship structures. Modeling, transformation and optimization, the three keyelements underlying the success of computational mechanics are adopted as the basicmethodology through the research. The whole work is presented in a way that is mostsuitable for software development.The foundation of the framework is constituted of reliability methods at component level.Looking at the second-moment reliability theory from a minimum distance point of viewthe author derives a generic set of formulations that incorporate all major first and secondorder reliability methods (FORM, SORM). Practical ways to treat correlation and non-Gaussian variables are discussed in detail. Monte Carlo simulation (MCS) also accountsfor significant part of the research with emphasis on variance reduction techniques in aproposed Markov chain kernel method. Existing response surface methods (RSM) arereviewed and improved with much weight given to sampling techniques and determinationof the quadratic form. Time-variant problem is touched upon and methods to convert it tonested reliability problems are discussed.In the upper layer of the framework common fatigue damage models are compared.Random process simulation and rain-flow counting are used to study effect of wide-bandednon-Gaussian process. At the center of this layer is spectral fatigue analysis based on SNcurve and first-principle stress and hydrodynamic analysis. Pseudo-excitation is introducedto get linear equivalent stress RAO in the non-linear ship-wave system. Finally responsesurface method is applied to this model to calculate probability of failure and designsensitivity in the case studies of a double hull oil tanker and a bulk carrier.