本文選題：海洋平臺　切入點：振動　出處：《華南理工大學》2015年碩士論文

【摘要】：隨著海洋資源開發(fā)進程的推進,海洋平臺的振動問題也越來越受到重視。關于海洋平臺的振動分析主要集中于環(huán)境荷載下的振動,而對于W12-1海洋平臺等長期服役的結構,其設備振動帶來的影響更大。平臺設備的振動,不僅直接影響設備的運行壽命,還會產生噪聲嚴重影響平臺人員的身體健康。為了抑制該類型的振動,需要準確地了解影響振動的若干要素,如平臺的結構參數(shù)(質量、剛度等)和荷載參數(shù)等。但是,對于長期服役的海洋平臺,其結構剛度的退化、工作和生活設備的變化等,使得結構與原設計有較大不同,結構參數(shù)難以正確估計;而載荷參數(shù)與結構參數(shù)相耦合,不僅與運行設備相關,而且和局部結構參數(shù)有關,更難以準確測量。本文針對這些存在的困難,通過對平臺進行大范圍的振動測量,分析平臺的振動特性,并在工程振動測量的基礎上,應用數(shù)值分析方法,發(fā)展了相關振動參數(shù)修正方法,合理地確定了平臺結構參數(shù)和荷載參數(shù)。具體工作包括:(1)對W12-1海洋平臺進行較全面的振動測試。測點布置圍繞下層和中層平臺進行布置,按照平臺結構特點分七組,一共51個測點。這七組測點,涵蓋了平臺不同類型的結構:壓縮機及周邊的構件、壓縮機附近的平面結構、遠離壓縮機的平面結構和層間立柱等。通過對測試信號的處理與分析,得到各個測點的位移時程曲線和相應的頻域曲線,進而通過分析得到海洋平臺各測點的振動平均幅值、局部結構的固有頻率以及激勵信號在該點的激振幅值等關鍵振動信息。實測數(shù)據(jù)表明每個測點存在振動頻率與壓縮機運轉頻率一致的振動信號,這說明海洋平臺振動的振源為壓縮機。對平臺進行振動測試與分析不僅能較全面地了解海洋平臺振動分布特征,并為進一步確定海洋平臺結構參數(shù)和荷載參數(shù)打下基礎。(2)根據(jù)初始設計圖紙,用梁和板殼單元建立了海洋平臺的空間有限元模型。在有限元模型中,對于結構剛度退化和設備質量不確定問題,等效地用附加質量方式加以考慮;壓縮機激振行為,用外加周期性荷載等效;振動求解則采用ABAQUS的顯式求解器進行求解和分析。這樣可以較精確地得到各測點的模擬加速度、位移等時程曲線,再進行相關的頻譜分析,以便和實測信號進行對比。而不采用簡單的模態(tài)分析法是因為海洋平臺結構十分復雜、自由度多,采用模態(tài)分析難以準確判斷各測點對應的模態(tài)。(3)針對長期服役的海洋平臺振動問題所表現(xiàn)的結構參數(shù)和激振參數(shù)難以準確估計的特點,基于實測數(shù)據(jù)的分析,確定了對平臺各層甲板設備質量以及激勵荷載值的修正思路。以各組控制點的振動平均幅值、局部結構的固有頻率以及激勵信號在該點的激振幅值等振動特征值作為目標控制參數(shù),對模型各層等效質量參數(shù)以及荷載參數(shù)進行修正。修正后的模型目標值與實測值在位移時程曲線和位移頻域曲線均勻較好的擬合,可以用于進一步的振動研究分析。
[Abstract]:With the development of marine resources to promote the process of vibration of offshore platform is also more and more attention. The vibration analysis of offshore platform focused on the environmental loads, and long-term service for W12-1 offshore platform structure, the influence of equipment vibration caused more vibration. Platform equipment, not only directly affects the service life the equipment, noise seriously affects the health of the workers on the platform will. In order to suppress the vibration of the type, need to accurately understand the influence of some factors such as vibration, the structure parameters of the platform (mass, stiffness) and load parameters. However, the long serving for the offshore platform, the degradation of the stiffness of the structure. The life and work of the equipment changes, the structure is quite different from the original design, the structure parameters are difficult to estimate; and the parameters and structural parameters of load coupling, not only with the operation of the equipment. Close, but also on the local structure parameters, more difficult to measure accurately. Aiming at these problems, through a wide range of vibration measurement platform, vibration analysis platform, and on the basis of engineering vibration measurement, numerical analysis method, the development of the vibration parameter correction method, to determine a reasonable structure platform parameters and load parameters. The specific work includes: (1) for a comprehensive vibration test of W12-1 platform. The lower and middle platform are arranged around the sensor arrangement, in accordance with the platform structure is divided into seven groups, a total of 51 points. The seven groups of measuring points, covering different types of structure: component platform the compressor and the surrounding the plane structure of compressor near, away from the compressor plane structure and inter layer column. Through the processing and analysis of the test signal, get a time history curve of each measuring point and the corresponding The frequency curve, and then through the analysis of offshore platform vibration amplitude of each point, the local structure of the natural frequency and the excitation signal at the point of the vibration amplitude of the vibration information. Key measured data indicate the presence of vibration signal and vibration frequency of compressor running frequency to each measured point, indicating that the source of vibration for the compressor. The testing and analysis of vibration on the platform not only can comprehensively understand the distribution characteristics of offshore platform vibration, and to further determine the offshore platform structure parameters and load parameters of foundation. (2) according to the original design drawings, the finite element model of the offshore platform established by using beam and shell element in finite element. In the model, the structural stiffness degradation and equipment quality uncertainty problem, equivalent to consider using additional mass method; compressor vibration behavior, with external periodic load Effect of vibration is solved; by using the explicit solver of ABAQUS are solved and analyzed. This can simulate the acceleration of each measuring point accurately, curves of displacement, then the analysis of the spectrum, and the measured signal for comparison. Instead of using a simple modal analysis method for offshore platform structures very complex, multi degree of freedom, using the modal analysis, it is difficult to accurately determine the modal point corresponding to each test. (3) the characteristics of structure parameters and vibration parameters according to the performance of offshore platform vibration of long serving is difficult to accurately estimate the measured data based on the analysis, determine the revision on the platform of the deck equipment quality and the load value. The average amplitude of each vibration control point, the local structure of the natural frequency and the excitation signal at the point of the vibration amplitude and vibration characteristic value as control parameters, the model The equivalent mass parameters and load parameters of each layer are corrected. The corrected target and measured values agree well with each other in displacement time history curves and displacement frequency domain curves, which can be used for further vibration analysis.

【學位授予單位】：華南理工大學
【學位級別】：碩士
【學位授予年份】：2015
【分類號】：P752

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