Study On Revised Forms And Parameters Optimization Of Dynamic Vibration Absorber

Dynamic vibration absorber(DVA) has been widely used in engineering practice for its properties such as efficiency, low cost and reliability. A dynamic vibration absorber usually consists of viscoelastic material and mass. The fractional-order calculus has many advantages in the modelling of the viscoelastic material, so that the optimal parameters of fractional-order dynamic vibration absorber is studied in this thesis. At the same time, two kinds of negative stiffness dynamic vibration absorbers are introduced to improve the control performance of the DVA in low frequency domain. The work in this thesis is as follow:(1) The fractional-order calculus is introduced to the Voigt type dynamic vibration absorber, and the approximate analytical solution is obtained by the averaging method. The optimum parameters are obtained by the definition of equivalent stiffness and damping based on the H∞ and H2 optimization criteria. And the comparison between the numerical solution and analytical solution shows the accuracy of the results in this thesis. At last the comparison with the traditional integer one shows the fractional order and coefficient can almost replace the linear stiffness and damping at the same time.(2) The negative stiffness is introduced to the dynamic vibration absorber where the damping element is connected directly to the earth. The optimum parameters for both damped and undamped primary system are all obtained when considering the effect of the negative stiffness on the system stability. The comparison with other two traditional DVAs shows the proposed model can largely reduce the resonance amplitude and broaden the vibration frequency range in lower domain.(3) The negative stiffness is also introduced to the Voigt type dynamic vibration absorber for the excellent performance by the damping element connected directly to the structure. The optimal parameters of the model is obtained for the primary system without damping. And the numerical simulation and comparison with other DVAs shows the negative Voigt model can also get a better control performance.At last, the contents of this thesis is summarized and some possible research directions in future are pointed out.