Analysis And Research On Novel Vibration Mitigation Systems

In the field of vibration control,vibration absorption and isolation are the main ways to reduce vibration.In the field of vibration absorption,the application of dynamic vibration absorber（DVA）is a common and efficient measure to reduce the amplitude of the system.In the field of vibration isolation,vibration isolator is an important measure to reduce the energy of transmission to the foundation or the object to be vibration isolation.However,the traditional vibration Mitigation Systems have poor control effect on low frequency vibration,while the inertia and the amplifying mechanisms have great performance in the field of low frequency vibration control.In order to improve the vibration performance of the system,a new design concept is proposed in this paper,in which the inertia and the amplifying mechanism are applied to the vibration systems.The main research contents are as follows:（1）A new three-element dynamic vibration absorber with amplifying mechanism is established,and the system performance of the three-element dynamic vibration absorber under optimal analytical solution was studied by H_∞optimization principle.The series viscoelastic model and amplification element were added to control the vibration of the system.The design formulae for the optimal tuning ratio and optimal stiffness ratio and the optimal damping ratio of the dynamic vibration absorber are derived by using the fixed-point theory and minimizing the peak value of the amplitude-frequency curves,which could better suppress the amplitude of the main system.（2）Lever component and inertia are introduced in dynamic vibration absorbers by Den Hartog（voigt）and Ren.The vibration absorption effects of the inertia between the main system with the vibration absorber and grounding are discussed,while the vibration absorption effects of four DVAs are studied.According to the fixed-point theory,the optimal parameters of the models are studied,and the influence of the inerter-to-mass ratio and amplification ratio on the vibration absorber are analyzed.Finally,it is shown that the vibration performances of DVAs are different with different inertia locations.If inertias are placed improperly,the vibration amplitude will not be suppressed,but increased.（3）Two kinds of vibration absorption systems with amplifying mechanism and inertia without vibration absorbing mass are proposed.The natural frequency changes of the vibration models with inertia and the lever component and the response changes under harmonic excitation and random excitation are studied.The parameters were optimized based on H_∞and H₂ criteria,and the vibration performances are analyzed in detail.（4）A new vibration isolation system with amplifying mechanism and inertia is proposed.According to the theory of vibration isolation,the design formulas for isolation efficiency evaluation associated with force transmissibility,insertion loss,vibration level difference and power flow rate are defined.In the end,compared with the power flow rates of general single-layer vibration isolation system and single-layer vibration isolation system with inertia,it is found that the isolation system with inertia and lever component can greatly improve the isolation efficiency and reduce the transmission of vibration energy in a specific frequency band.Finally,the advantages of the vibration absorber with inertia and lever component in the field of vibration control are summarized,and the performances of the vibration absorber and isolator with two kinds of amplification mechanism are described in detail.In addition,the problems of friction loss and space restriction that need to be solved in the future are prospected.