Study On Vibration Reduction Performance And Force Model Of Pounding Tuned Mass Damper

Tuned mass damper(TMD) is one of the most widely used passive control devices in structural vibration control. The pounding tuned mass damper(PTMD) is a new type of passive vibration damping device using the inertia force and the pounding force to reduce the structural vibration. On the basis of TMD, a baffle was added to limit the displacement of TMD and a layer of viscoelastic material was arranged between the baffle and the mass in PTMD. PTMD has advantages of small space and good robustness, and is a kind of vibration reduction technology with wide application prospect. In order to determine the optimal design parameters of PTMD,the pounding force model is required to carry out a further study. Based on the review of PTMD research status, two kinds of materials were used to carry out experimental and theoretical research for the pounding force model. According to the force and displacement obtained from test, the particle swarm optimization(PSO) algorithm was used to identify the parameters of the pounding force model. The vibration reduction performance of PTMD under the free vibration and the excited vibration was analyzed. The main research work includes:(1)The research situation of TMD and the present situation in domestic and foreign research of PTMD were introduced, and the main content and significance of this dissertation were established. According to several common contact mechanics model, the approximate damping constant expressions were discussed. The energy dissipation mechanism and nonlinear characteristics of viscoelastic materials in the process of collision were summarized. And the concept of elastic aftereffect was introduced. All the above have established the theoretical foundation for the further study of PTMD.(2)The pounding force test model of PTMD was made, and according to the three pounding types of sphere, cylinder and plane, the pounding test between twokinds of viscoelastic material and steel block was carried out. The pounding force and the indentation displacement time history of pounding processes were obtained. The influence of the cycle times, initial release distance, material thickness and contact surface on the pounding force was discussed. The indentation before and after pounding, the elastic recovery coefficient of the two kinds of materials were analyzed.(3)Base on the classical Hertz-damp contact theory, the viscoelastic pounding force model was presented, and the nonlinear pounding force equation which included elastic restoring force and damping force was established. Based on the energy conservation principle, the relationship of pounding stiffness, nonlinear exponent and pounding damping coefficient was identified. Focusing the optimization goal to pounding force, and according to the pounding force and the indentation displacement obtained by test, the parameters such as pounding stiffness and nonlinear exponent have been identified by using the particle swarm optimization(PSO) algorithm. The experimental values and model theoretic calculated values under different working conditions were compared and analyzed.(4) The motion equation of a single degree of freedom structure-PTMD system was established. The vibration reduction performance simulation analysis of TMD and PTMD were conducted under three conditions as follows: free vibration,harmonic excitation and random excitation. Meanwhile, the vibration reduction performance of different viscoelastic materials, the control robustness and optimized parameters of PTMD were also studied, and the vibration reduction performance of PTMD is evaluated comprehensively.