本文選題：疲勞分析 + S-N曲線法　； 參考：《中國海洋大學(xué)》2014年碩士論文

【摘要】：隨著我國經(jīng)濟(jì)的飛速發(fā)展，能源的需求量也越來越大，加速我國海上油氣資源開發(fā)是當(dāng)務(wù)之急。淺海導(dǎo)管架平臺(tái)與深海浮式平臺(tái)作為目前海上石油開發(fā)普遍采用的形式，在隨機(jī)波浪載荷作用下會(huì)產(chǎn)生累積疲勞損傷，嚴(yán)重的會(huì)發(fā)生疲勞破壞，造成嚴(yán)重后果。隨著平臺(tái)服役年限的增長(zhǎng)和平臺(tái)老化問題的日益加劇，疲勞損傷已成為海洋平臺(tái)構(gòu)件損傷的重要原因。因此疲勞壽命分析和評(píng)估研究對(duì)海洋平臺(tái)的安全至關(guān)重要。 本文系統(tǒng)回顧了疲勞分析相關(guān)理論和常用的疲勞分析方法，，對(duì)疲勞分析的研究現(xiàn)狀及非線性因素對(duì)疲勞分析影響進(jìn)行了論述，重點(diǎn)針對(duì)非線性波浪力對(duì)海洋平臺(tái)疲勞壽命評(píng)估的影響展開研究工作，主要研究?jī)?nèi)容和創(chuàng)新點(diǎn)如下： 1)本文系統(tǒng)研究了頻域法、確定性法和時(shí)域法三種疲勞分析方法，開展了針對(duì)導(dǎo)管架平臺(tái)的疲勞壽命評(píng)估工作，對(duì)比和分析了不同疲勞分析方法所得疲勞壽命。將時(shí)域法計(jì)算結(jié)果作為基準(zhǔn)，則得出確定性法高估結(jié)構(gòu)疲勞壽命和頻域法低估疲勞壽命的結(jié)論。同時(shí)，在頻域方法中考慮循環(huán)計(jì)數(shù)修正因子可以提高頻域法分析結(jié)果的準(zhǔn)確性。 2)本文在確定性方法中根據(jù)線性波與Stokes5階波的適用條件引入非線性波浪理論，并針對(duì)導(dǎo)管架平臺(tái)開展疲勞壽命分析工作，研究并分析了非線性波浪理論代替線性波浪理論后對(duì)疲勞壽命結(jié)果的影響。通過計(jì)算可以得出引入Stokes5階波浪理論以后，結(jié)構(gòu)的疲勞壽命有所增加，增加量在20%左右，影響較為明顯。 3)針對(duì)小樁柱求解波浪力時(shí)普遍使用線性化波浪力譜計(jì)算的現(xiàn)狀，本文在疲勞計(jì)算中引入了非線性拖曳力譜，推導(dǎo)了非線性波浪力譜表達(dá)式，并針對(duì)導(dǎo)管架平臺(tái)結(jié)合非線性波浪力譜進(jìn)行疲勞分析。計(jì)算結(jié)果表明，增加非線性拖曳力譜修正項(xiàng)的影響后，導(dǎo)管架平臺(tái)的疲勞壽命減少10%左右，對(duì)疲勞結(jié)構(gòu)有較大影響。 4)深海浮式平臺(tái)系泊系統(tǒng)在受到波頻波浪力作用的同時(shí)，還會(huì)受到二階差頻波浪力的影響，且在疲勞計(jì)算中經(jīng)常被忽略。本文為研究二階差頻波浪力對(duì)深海平臺(tái)系泊系統(tǒng)的影響，進(jìn)行了深海平臺(tái)系泊系統(tǒng)的時(shí)域耦合分析，分別計(jì)算波頻張力時(shí)程、差頻張力時(shí)程和總張力時(shí)程，利用波頻張力時(shí)程、差頻張力時(shí)程和總張力時(shí)程進(jìn)行疲勞損傷與疲勞壽命的計(jì)算。研究結(jié)果表明，差頻波浪力引起的疲勞損傷度在總損傷度占有一定比例。說明對(duì)于深海浮式平臺(tái)的疲勞壽命評(píng)估必須考慮二階差頻的影響.
[Abstract]:With the rapid development of China's economy, the demand for energy is increasing. It is urgent to accelerate the development of offshore oil and gas resources in China. Shallow water jacket platform and deep-sea floating platform are widely used in offshore oil development at present. Under random wave loads, cumulative fatigue damage will occur, and fatigue damage will occur seriously, resulting in serious consequences. With the increase of the service life of the platform and the increasing aging of the platform, fatigue damage has become an important reason for the damage of offshore platform members. Therefore, fatigue life analysis and evaluation are very important to the safety of offshore platforms. In this paper, the related theory of fatigue analysis and the commonly used fatigue analysis methods are reviewed systematically, and the research status of fatigue analysis and the influence of nonlinear factors on fatigue analysis are discussed. Focusing on the influence of nonlinear wave forces on fatigue life assessment of offshore platforms, the main contents and innovations are as follows: 1) in this paper, three fatigue analysis methods, frequency domain method, deterministic method and time domain method, are systematically studied. The fatigue life evaluation for jacket platform is carried out, and the fatigue life obtained by different fatigue analysis methods is compared and analyzed. Based on the results of time-domain method, it is concluded that the deterministic method overestimates the fatigue life of structures and the frequency-domain method underestimates the fatigue life. At the same time, the accuracy of the analysis results can be improved by considering the cyclic counting correction factor in the frequency domain method. 2) in the deterministic method, the nonlinear wave theory is introduced according to the applicable conditions of linear wave and Stokes5 order wave, and fatigue life analysis of jacket platform is carried out. The influence of nonlinear wave theory instead of linear wave theory on fatigue life is studied and analyzed. It can be concluded by calculation that the fatigue life of the structure increases by about 20% after the introduction of Stokes5 wave theory, and the effect is obvious. 3) in view of the current situation that linearized wave force spectrum is widely used in solving wave force of small pile column, nonlinear drag force spectrum is introduced in fatigue calculation, and nonlinear wave force spectrum expression is derived. Fatigue analysis of jacket platform combined with nonlinear wave force spectrum is carried out. The results show that the fatigue life of jacket platform is reduced by about 10% with the addition of the correction term of nonlinear drag force spectrum, which has great influence on the fatigue structure. 4) the mooring system of deep-sea floating platform is affected by the wave force and the second-order differential wave force, which is often neglected in fatigue calculation. In order to study the influence of second-order differential wave force on the mooring system of deep-sea platform, the time-domain coupling analysis of deep-sea platform mooring system is carried out. The wave-frequency tension time history, differential frequency tension time history and total tension time history are calculated respectively, and the wave-frequency tension time history is used. The fatigue damage and fatigue life were calculated by the time history of differential tension and total tension. The results show that the fatigue damage caused by differential wave force accounts for a certain proportion of the total damage. It shows that the influence of second order difference frequency must be considered for fatigue life evaluation of deep sea floating platform.
【學(xué)位授予單位】：中國海洋大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2014
【分類號(hào)】：P731.22;P751

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本文編號(hào)：1948394