【作者】 屈召富；

【导师】 孙家林；

【作者基本信息】 山东大学 ， 机械工程， 2008， 硕士

【摘要】 海洋平台是海上石油天然气资源开发的基础设施。平台的有效振动控制已成为延长平台使用寿命、提高平台可靠性、改善平台工作人员的舒适感的重要措施。因此,如何减轻平台在各种载荷作用下的振动日趋重要。本文对ETMD(METMD)减振系统在海洋平台中的减振效果进行研究。第一,利用海洋平台上的设备和装置作为质量体构造ETMD减振系统。为分析ETMD减振系统的振动控制效果,将海洋平台和ETMD减振系统简化为二自由度系统进行研究。同时,引入振动控制效果评价指数作为减振效果评价指标,研究各个参数对振动控制效果的影响。结果表明,影响ETMD系统振动控制效果的参数有系统的阻尼比、固有频率比和质量比,各参数的取值不同,振动控制效果也不同。第二,为得到ETMD减振系统的最优参数,根据二自由度动力学方程,编写了MATLAB程序。得到最优振动控制效果下ETMD系统的参数及最优参数区间。第三,为提高ETMD减振系统的减振效果,在结构上设置多个不同的固有频率ETMD减振系统(METMD减振系统),形成一个频率范围。提高了复杂载荷作用下平台的减振效果。首先把平台简化为单自由度系统(SDOF系统),利用多个ETMD减振系统(METMD减振系统)进行振动控制,理论分析了S-METMD系统的频带宽度、阻尼比和ETMD数量三大因素对海洋平台振动控制效果的影响,并得到了最优参数。接着,把海洋平台简化为多自由度系统(MDOF系统),研究METMD减振系统对平台的振动控制效果。对M-METMD系统进行了理论分析,得到了简化研究方法,为复杂系统的研究奠定了基础。最后,为验证ETMD减振系统对海洋平台的振动控制效果,利用时程分析法研究了平台在海浪和地震载荷作用下的振动响应。根据波浪阻力线性化理论推导出波浪载荷公式,利用Matlab编制程序,生成不同有效波高波浪随机载荷时程曲线来研究组合抗振海洋平台在恶劣海浪下的响应;选取El-centro、Taft和宁河三类典型地震波,根据8度罕遇地震的标准调整了加速度幅值,研究组合抗振海洋平台在三维地震载荷作用下的动态响应和振动情况。仿真结果表明,ETMD(METMD)减振系统能够有效的控制海洋平台的振动。总之,理论分析和仿真研究表明,ETMD(METMD)减振系统对海洋平台的振动具有显著的控制效果。根据满足固有频率相似条件的方法,设计的海洋平台模型能够满足相似条件,为下一步的研究奠定了基础。在后续研究中,将制造模拟平台,对ETMD减振系统在海洋平台控制中的应用做进一步的研究。更多还原

【Abstract】 The offshore platforms are the bases of offshore oil and gas exploitation. Vibration control techniques for offshore platforms are important methods to extend the service life, enhance reliability of the platforms and improve the comfortable feeling of the workers. Some researches on the effect of the extended tuned mass damper (ETMD) system and multiple extended tuned mass dampers (METMD) for vibration control of offshore platforms were done in this dissertation.Firstly, the ETMD system is constructed by using the equipments of offshore platform as the mass body. The offshore platform, on which one mass body is chosen as an ETMD system, is simplified as a double-degree-of-freedom system in the research. In order to analyze the influence of all parameters to the vibration control effects, the appraisal index of vibration control effect is introduced to study the vibration control effect of the ETMD system. The influence of all parameters to the vibration control effect of ETMD system is studied. The results show that the parameters, which influence the vibration control effect, are the ratios of damping, natural frequency and mass. The values of the parameters of the ETMD system determine the vibration control effect. Different values have different influence on the vibration control effect.Secondly, the optimal parameters and optimal parameter regions are given by making use of the software of MATLAB. The ETMD system has the best vibration control effect when the parameters take the optimal parameters and has better vibration control effect when the parameters take values in the optimal parameter regions.Thirdly, several ETMD systems, which have the different frequencies, are set on the platform in order to increase the vibration control effect. Firstly, the platform is simplified as a single-degree-of-freedom system to do research. Several ETMD systems are assigned on the platform in order to enlarge the frequency band of the controlled loads. Then, the platform, on which several mass body are chosen as ETMD systems, is simplified as a multiple-degree-of-freedom system to analyze the effect of frequency bandwidth, damp ratio and ETMD’s number to the platform’s vibration control and find out their optimal parameters. The vibration control effect on the offshore platform of the ETMD (METMD) system is simulated by using the software of ANSYS, which is subjected to random loads of wave and earthquake. It shows that the ETMD (METMD) system can reduce the vibration of the offshore platform effectively.Lastly, the response of the platform with the ETMD’s vibration control under the ocean wave and earthquake loads is researched using the time-history method in the dissertation. The formula of the ocean wave load is derived based on the resistance force linearizing theory. And the loads of different significant wave height are gotten using the MATLAB program. In order to analyze the dynamic response and the vibration of the platform under the random seismic loads, El-centro, Taft and Ninghe seismic waves are chosen and their maximum acceleration have been adjusted according to 8 level fortification under rarely occurred earthquake. The ETMD system has the better vibration control effect under the two random loads mentioned above.In conclusion, the theoretical analysis and the simulation show that the ETMD system has marked effect for vibration control of offshore platforms. The similar model of the offshore platform, which is based on the new method for satisfying the similar condition of the natural frequency ratio, establishes the foundation of the next study. A model platform will be made to study the application of the offshore platform vibration control to the ETMD system in the follow-up research.更多还原