Research Of A Dynamic Vibration Absorber With Wideband Resonant Frequency

Modern industry has brought us a brand new lifestyle with unprecedented convenience and efficiency. However, vibration and correlated noise accompanied with those advance machines are negatively affecting living environment, human health and both accuracy and service life of equipments. As an effective damping measure, Dynamic Vibration Absorber (DVA) technology is widely used in modern industry for its simple structure, low cost and simple control strategy.A new kind of DVA is presented in this thesis. One the one hand, its natural frequency can be real-time adjusted by adapting rigidity of its springs. The rigidity of the springs can be adjusted by compressing or stretching curved beams. On the other, the working frequency range of the DVA can also be adjusted by replacing different adjustable mass. A physical model and a mathematical model of the spring group are built respectively. A theoretical linear relation between effective rigidity of the spring group and square of span between screw nuts is founded. And effective rigidity of the spring group is only related to section size and radius of the spring. Vibration attenuation characteristics are analyzed both theoretically and numerically. A linear relation between natural frequency of the DVA and the span of the screw nuts is founded, as well as frequency shift characteristics of the DVA, and frequency shift radio can reach77%.By means of numerical simulation analysis, damping effects of the DVA working on a plate loading with harmonic force are researched. The results show that the damping effect can reach9dB, and better damping effects can be got when installation site of the DVA is closer to vibration source.In order to make the DVA to achieve an optimal damping effect, a stepwise optimization is performed. At first, a kinematics differential equation is built and a mathematical model of the steady-state amplitude of vibration system is found, four main system parameters involving the ratios of massμ, natural frequency f,vibration frequency g and damping ζ are solved by small-step-search method to obtain optimal steady state amplitude. Then the sizing optimization of the dynamic vibration absorber is proceeded to search an optimal damping effect based on the optimal parameters μ,f, g,ζ. The damping effect is simulated in a flat structure; the results show that the damping effect reaches11.8dB, a30%improvement after optimization.In order to achieve a better damping effect in broadband vibration environment, a topological optimization is carried out assisted by commercial Finite Element Method (FEM) code HyperWorks. The FEM analysis shows that, the DVA attains more modal distribution in the frequency band range of0-200Hz, and damping effect averagely reaches5dB within50Hz-200Hz, achieving a25%enhancement.