Study On Adaptive Tuned Vibration Absorbing Technology

Tuned vibration absorbers (TVAs) are widely used in industries to suppress undesirable vibrations of machines excited by harmonic forces. However, the TVA is only effective in a narrow frequency range. As the excitation frequency varies, the vibration attenuation effect of the TVA decreases or even collapses because of mistuning. This problem limits many practical applications of the TVAs. One solution is to develop an adaptive tuned vibration absorber (ATVA). By adjusting a resonant frequency in real time to track the excitation frequency, the ATVA is able to improve the vibration attenuation performance significantly. In recent years, the adaptive tuned vibration absorbing technology has been developed rapidly. However, in real engineering applications, many issues are still needed to be dealt with appropriately. These issues include:poor vibration attenuation performance of the device, low level of practical applications, and lack of the application research. Therefore, further research on the adaptive tuned vibration absorbing technology is crucial in theory and engineering application. This dissertation reports both theoretical and experimental researches on the adaptive tuned vibration absorbing technology. The developed technology is also an aim of national application technology research. The main contents include three parts:(a) design of a mechanical ATVA, (b) application of the ATVA to a multi-modal system; and (c) research on the active-adaptive vibration absorber (AAVA).In the design and development of the ATVA, several key factors in influencing the vibration attenuation effect were analyzed. These analyses led to a novel mechanical ATVA with the variable stiffness as the heart. The natural frequency of the device can be adjusted in real time by adjusting its geometry parameters. The proposed ATVA was prototyped and it has the advantages of compact structure, high utilization of the mass and so on. The dynamic performance of the ATVA was experimentally evaluated, which indicates that the ATVA has wide frequency-shift range and low damping ratio. An optimal variable step-size control strategy of the ATVA was investigated. The validity of this strategy was verified via simulation.The application of the ATVA to a multi-modal system was also investigated through both theoretical and experimental approaches. The theoretical study firstly set up the mathematics model of the system with transmission mobility method. The vibration attenuation effects of the ATVAs installed at different mounting positions were analyzed and compared; the optimal installing position was determined. The experimental study in terms of the vibration attenuation effect of the ATVA was conducted with a self-made massive multi-mode experimental platform. Furthermore, the finite element method was employed to analyze the ATVA performances, which agreed well with experimental results.To further improve the performance of the ATVA, an active-damping-compensated magnetorheological elastomer adaptive tuned vibration absorber (AAVA) was designed and prototyped. The principle and the vibration attenuation performance of the proposed AAVA were theoretically analyzed. Based on the analysis, an effective control strategy of the AAVA was developed. This control strategy used the velocity signal of the oscillator as the feedback control signal. The dynamic properties of the MRE AAVA prototype and its vibration attenuation performances were experimentally investigated. The experimental results demonstrated that the damping ratio of the developed AAVA was significantly reduced by the active force. Consequently, its vibration attenuation capability was significantly improved compared with the conventional MRE ATVA. This demonstrates that the developed method is effective for improving the performance of the absorber. Additionally, the coupling system model of the beam and the AAVA was developed and analyzed. The simulation results agree well with the experimental results.