| Dynamic vibration absorber is a common vibration control method,which can reduce the impact of vibration in daily life.Dynamic vibration absorbers can be divided into three types:passive,semi-active and active.Among them,semi-active vibration absorbers are widely used due to their advantages of broadening the damping frequency band and reducing energy consumption during the damping process.Magnetorheological elastomer(MRE)materials are not easy to settle,have good stability,and have variable stiffness.Therefore,this paper proposes a semi-active MRE dynamic vibration absorber which combines MRE material with traditional dynamic vibration absorber.Using MATLAB/Simulink to establish a simulation model,the frequency shift characteristics and vibration damping performance of the semi-active MRE dynamic vibration absorber are simulated and analyzed,and a vibration test-bed is built to test and analyze the acceleration response of the main system under fixed frequency and sweep frequency,respectively,to verify the effectiveness of the designed vibration absorber.The main research contents of this paper are as follows:1.Silicone rubber,silicone oil and carbonyl iron powder with particle size of 5-7 μm were selected as preparation materials,and three kinds of magnetorheological elastomers with carbonyl iron powder content of 70%,60% and 40% are prepared respectively.During curing,an external magnetic field of 0m T,300 m T,600 m T and 900 m T is applied respectively.The rheological properties are tested with MCR 302 rotary rheometer,and the changes of shear storage modulus and loss modulus are analyzed,and the test and analysis results are compared.MRE with the best magnetorheological effect is selected as the variable stiffness element in the dynamic vibration absorber.2.A semi-active MRE dynamic vibration absorber is proposed.Symmetrical excitation coil is used to increase the maximum magnetic field that can act on MRE material and achieve better vibration reduction effect.Starting from the structure of the designed semi-active MRE dynamic vibration absorber,the materials of the vibration absorber are selected,and the magnetic circuit is simulated and analyzed using Maxwell 16.0 software to determine the structural parameters to ensure that the magnetic induction intensity through MRE meets the requirements.3.According to the dynamic model of the dynamic vibration absorber,the dynamic simulation model is built using MATLAB/Simulink,and the frequency shift characteristics and vibration damping performance of the semi-active MRE dynamic vibration absorber are analyzed from the frequency domain and the time domain respectively.Through the simulation analysis,it is shown that the semi-active MRE dynamic vibration absorber can broaden the damping frequency band,and the vibration control effect of the main system is more obvious when the natural frequency and external excitation frequency are close or equal.In the frequency sweep simulation,in order to eliminate the resonance peak caused by the addition of vibration absorber,a stiffness adjustment method is proposed.The simulation results show that the method is effective.4.The semi-active MRE dynamic vibration absorber is used to build a vibration system test platform,and its frequency shift characteristics and vibration damping performance are analyzed experimentally.In the experiment,the control current changes the MRE stiffness,and then achieves the purpose of adjusting the natural frequency of the semi-active MRE dynamic vibration absorber.The acceleration response changes of the main system with or without vibration absorbers under different excitation and current are tested respectively,and the response changes are analyzed and compared.It is proved that the semi-active MRE dynamic vibration absorbers designed in this paper can broaden the damping frequency band and have good damping effect,which shows the correctness of the design and achieves the expected design objectives. |
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