Frequency Adjustable Tuned Mass Damper Based On Magnetorheological Elastomers

After long-term use,the natural frequency of the main structure will change to a certain extent due to reasons like stiffness degradtion,fatigue damage.The parameters of tradtional tuned mass damper(TMD)is fixed after installation.At this time it can not achieve a good damping effect due to the mismatch of paramters with the main structure.Magnetorheologcal elastomer(MRE)is a new kind of smart material,whoes modules can be changed with the change of exteral magnetic field.This paper proposed a frequency adjusatble TMD based on MRE and then carried out the corresponding research.This paper is divided into five chapters.The research status of TMD and MRE are introduced in chapter one;The fabrication,performance and physical model of MRE is introduced in chapter two;The working principle of TMD and the related stiffness adjustable strategy are described in chapter three;in the fourth chapter,the natural frequency identification method of structure whoes dynamic characteristics is detailly introduced.Lastly a long time used pedestrain bridge is used as an example to compare the vibration reduction effect between traditional TMD and this kind of frequency adjustable TMD.In this paper,the following results are obtained:(1)when the main structure is used for a long time,the parameters of traditional TMD is not matched with the main structure thus the effect of vibration reduction is weaken.(2)The combination of FFT,HHT and NExT is an effective method to identify the modal parameters of nonlinear and unstable signals.(3)The stiffness adjustable method of frequency adjustable TMD based on MRE is correct and it can obtain a good damping effect in a wider frequency band compared to traditional TMD.