A Novel Semi-active Tuned Mass Damper With Tunable Stiffness

The harm brought by vibration exists widely in people's life.With the rapid development of social and economic level,the demand for vibration control of civil structures and mechanical systems is increasingly fierce.As an effective vibration control method,Semi-Active Tuned Mass Damper(SATMD)with tunable stiffness has attracted more and more attention.Compared with optimizing the main structure design and increasing the actuator to provide external forces,tunable stiffness SATMD has higher economy and stability.Firstly,the vibration damping principle and design principle of Passive Tuned Mass Damper(PTMD)are introduced in detail,and the influence of parameters of PTMD on the amplitude of main structure is revealed through numerical analysis by introducing examples,thus providing a theoretical basis for the study of variable stiffness SATMD.Secondly,the working principles and characteristics of tunable stiffness mechanism(TSM)in the tunable stiffness SATMD was analyzed in detail.TSM consists of a rigid rotating piece and two cylindrical helical springs.The first step introduces the structure of TSM.According to the structure,the mathematical model of stiffness adjustment is established.Then a drive part is designed for rigid rotating piece,a contact model between rotating parts and spring rigidity is established,the functional relationship between the torque required for rotating the rigid rotating piece and the position of the rigid rotating parts and the tensile length of TSM is deduced.Finally,the energy conversion relationship in the whole stiffness adjustment process is analyzed in detail.The analysis results show that most of the external torque work overcomes the friction between the rigid rotating part and the spring,and a small part is converted into elastic potential energy stored in the spring.Finally,the vibration control algorithm is proposed,the vibration damping device is designed,the vibration experiment platform is built,and the vibration damping performance of the proposed variable stiffness SATMD is tested.Seventeen different excitation frequencies were selected in the experiment,and the stiffness of SATMD was adjusted to adapt to these different excitation frequencies in combination with the control algorithm during the experiment.Finally,the influence of the adjusting speed of SATMD stiffness on the vibration of the main structure was studied.The experimental results show that the proposed variable stiffness SATMD can effectively reduce the amplitude of the main structure within the range of excitation frequency ratio 0.8?1.2.Compared with traditional PTMD,the vibration damping performance of SATMD with variable stiffness is greatly improved.