海洋平台振动测量及模型与荷载修正

发布时间：2018-03-28 19:24

本文选题：海洋平台　切入点：振动　出处：《华南理工大学》2015年硕士论文

【摘要】：随着海洋资源开发进程的推进,海洋平台的振动问题也越来越受到重视。关于海洋平台的振动分析主要集中于环境荷载下的振动,而对于W12-1海洋平台等长期服役的结构,其设备振动带来的影响更大。平台设备的振动,不仅直接影响设备的运行寿命,还会产生噪声严重影响平台人员的身体健康。为了抑制该类型的振动,需要准确地了解影响振动的若干要素,如平台的结构参数(质量、刚度等)和荷载参数等。但是,对于长期服役的海洋平台,其结构刚度的退化、工作和生活设备的变化等,使得结构与原设计有较大不同,结构参数难以正确估计;而载荷参数与结构参数相耦合,不仅与运行设备相关,而且和局部结构参数有关,更难以准确测量。本文针对这些存在的困难,通过对平台进行大范围的振动测量,分析平台的振动特性,并在工程振动测量的基础上,应用数值分析方法,发展了相关振动参数修正方法,合理地确定了平台结构参数和荷载参数。具体工作包括:(1)对W12-1海洋平台进行较全面的振动测试。测点布置围绕下层和中层平台进行布置,按照平台结构特点分七组,一共51个测点。这七组测点,涵盖了平台不同类型的结构:压缩机及周边的构件、压缩机附近的平面结构、远离压缩机的平面结构和层间立柱等。通过对测试信号的处理与分析,得到各个测点的位移时程曲线和相应的频域曲线,进而通过分析得到海洋平台各测点的振动平均幅值、局部结构的固有频率以及激励信号在该点的激振幅值等关键振动信息。实测数据表明每个测点存在振动频率与压缩机运转频率一致的振动信号,这说明海洋平台振动的振源为压缩机。对平台进行振动测试与分析不仅能较全面地了解海洋平台振动分布特征,并为进一步确定海洋平台结构参数和荷载参数打下基础。(2)根据初始设计图纸,用梁和板壳单元建立了海洋平台的空间有限元模型。在有限元模型中,对于结构刚度退化和设备质量不确定问题,等效地用附加质量方式加以考虑;压缩机激振行为,用外加周期性荷载等效;振动求解则采用ABAQUS的显式求解器进行求解和分析。这样可以较精确地得到各测点的模拟加速度、位移等时程曲线,再进行相关的频谱分析,以便和实测信号进行对比。而不采用简单的模态分析法是因为海洋平台结构十分复杂、自由度多,采用模态分析难以准确判断各测点对应的模态。(3)针对长期服役的海洋平台振动问题所表现的结构参数和激振参数难以准确估计的特点,基于实测数据的分析,确定了对平台各层甲板设备质量以及激励荷载值的修正思路。以各组控制点的振动平均幅值、局部结构的固有频率以及激励信号在该点的激振幅值等振动特征值作为目标控制参数,对模型各层等效质量参数以及荷载参数进行修正。修正后的模型目标值与实测值在位移时程曲线和位移频域曲线均匀较好的拟合,可以用于进一步的振动研究分析。
[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.

【学位授予单位】：华南理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：P752

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