Study On The Vibration Control Of Marine Equipment By TMD

The low-frequency vibration control of marine equipment is a difficult problem of vibration control, while the low-frequency vibration of equipment after a vibration isolation system would be partly attenuated, but main frequency peak still exists, so the primary problem of marine equipment’s low-frequency vibration control is to control the main frequencies vibration. Low-frequency vibration frequencies of marine equipment are mainly rotation frequency and double frequency. Vibration Absorption is a technique for effective control of low-frequency vibration of mechanical and electrical equipment and its application in engineering is mainly in the form of tuned mass dampers. TMD is a oscillating system composed of mass, spring and damper and the mechanism is that inertia force through the mass is provided, so as to reduce the vibration of the controlled structure.A set of land simulation device is designed for simulating marine equipment’s low-frequency vibration, targeting with reducing simulation device’s low-frequency vibration, two structure forms of TMD are designed, and applying TMD to control its characteristic frequency vibration. By theoretical calculation analysis and large of test validation analysis, quality ratio, frequency, damping ratio and installation location on effects of the vibration absorption effect and robustness are researched. The annular TMD satisfying the engineering demand is designed to solve the matter that rotation frequency vibration of the compressor sets is out of limits. The main research contents and results are as follows: 1. By the analysis of marine equipment’s low-frequency vibration characteristics, a set of land simulation device is designed for simulating marine equipment’s low-frequency vibration. The device is composed of a work unit, the vibration isolation system etc. The work unit plans to use the frequency modulation motor. The vibration isolation system consists of a set of single layer vibration isolation system, in order to study how modal frequency can influence vibration absorption effect and robustness, when equipment installation rack is designed, try to make the first order elastic body frequency be close to or away from the excitation frequency. 2.Through the analysis of rigid body model, quality ratio, frequency and damping ratio on effects of the vibration absorption effect and robustness is researched. And land simulation device as the research object, on this basis installation location on effects of the vibration absorption effect and robustness is intensively researched by application of harmonic, and the effect of mass ratio, damping ratio and TMD frequency influenced on vibration absorption effect and robustness is verified. Research shows that the influence of TMD installation position and arrangement on the vibration absorption effect are significant and increasing the mass ratio, reducing the damping ratio can both increase the vibration absorption effect and robustness, while the offset of TMD frequency only affects vibration absorption effect at excitation frequency. 3.Two kinds of different structural TMDs of cantilever beam TMD and rubber TMD are designed. The effective length of cantilever beam TMD is calculated by the application of the mode extraction method and by two estimation methods of the application of modal extraction method, and static stiffness method, the rubber hardness of rubber TMD is calculated. By comparison with experimental values, for cantilever beam TMD, the modal method can estimate the effective length and is high-precision. For rubber TMD structure, mode method and static stiffness method can be used in the estimation of the rubber hardness. The average value of the two kinds of calculation method for estimating the rubber hardness as the cast hardness is more close to the actual hardness. 4.TMD test was done on land simulation device and compared with the theoretical analysis. Research shows that the influence of TMD installation position and arrangement on the vibration absorption effect are significant and the selection of the best installation location is not only related to the vibration acceleration response and transmission paths, the local modal of the installation location also has an effect on the vibration absorption effect. The frequency of TMD has a significant effect on vibration absorption effect and in general, the maximum vibration absorption effect will appear when the TMD natural frequency is slightly larger than the excitation frequency. For a TMD system, increasing the mass ratio and reducing the damping ratio will make the vibration absorbing effect and robustness increase. When controlling the vibration of multiple excitation frequencies, different TMDs according to the different frequency are installed to control the vibration, under normal circumstances, multiple frequencies does not produce interference each other, and the vibration absorption effect of multiple frequencies and that of single frequency vibration absorption effect are consistent. When the main system after the installation of TMD, low-frequency vibration isolation effect will be better, so the full-frequency vibration isolation effect will be better. 5.Referring to the characteristics of two kinds of TMD and considering the working environment and reliability, the annular TMD satisfying the engineering demand is designed to solve the matter that rotation frequency vibration of the compressor sets is out of limits.Through the above research, a set of design method and an engineering method of debugging TMD is summed up, and it has certain referential significance for application of TMD to control low-frequency vibration.