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Owing to its easy implementation and robustness, the pounding tuned mass damper (PTMD), which uses viscoelastic materials to cover the pounding boundary to increase the energy dissipation during impact, has been studied in recent years. The conventional PTMD design includes a gap between the pounding mass and the viscoelastic material; the value of this gap should be optimized. In this paper, a novel PTMD is proposed to control structural vibrations. In the proposed PTMD, the pounding boundary covered by viscoelastic materials is simply added to one side of the tuned mass when the tuned mass is in the equilibrium position. Unlike the conventional PTMD, the gap between the tuned mass and the pounding boundary is zero in the proposed design and is no longer a design parameter. A new analytic model is proposed to accurately predict the impact force between viscoelastic materials and steel. Through comparison with the impact force and the indentation from impact experiments, the accuracy of the proposed impact force model is validated. To verify the control performance of the proposed PTMD, an experimental study on a frame with the proposed PTMD is carried out to investigate the control performance in free vibration and forced vibration cases. Both experimental and numerical results show that the proposed PTMD can effectively reduce the response of the frame structure and that the damping ratio of the frame is significantly increased.

In the case of a thin surface precision mechanical device, it is often accompanied by mechanical vibration, mechanical vibration will reduce the precision of the device. In order to eliminate the influence of the vibration, the surface eddy current damper is introduced, which can quickly generate the damping force of multi degree of freedom, and has the advantages of simple structure, high safety and reliability. The mechanism of the eddy current damper is analyzed, and based on the calculation and analysis of the electromagnetic damping force, the vibration suppression effect of the eddy current damper is designed. The experimental results show that the surface mechanical device of precision parts vibration when using eddy current damper, vibration suppression of surface mechanical device type disk can be effective, the fast response speed, high reliability and safety, which has important reference value for the study of vibration reduction of panel type precision machinery parts.

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Undesirable vibrations occurring in undersea pipeline structures due to ocean currents may shorten the lifecycle of pipeline structures and even lead to their failure. Therefore, it is desirable to find a feasible and effective device to suppress the subsea vibration. Eddy current tuned mass damper (ECTMD), which employs the damping force generated by the relative movement of a non-magnetic conductive metal (such as copper or aluminum) through a magnetic field, is demonstrated to be an efficient way in structural vibration control. However, the feasibility and effectiveness of ECTMD in a seawater environment has not been reported on before. In this paper, an experiment is conducted to validate the feasibility of an eddy current damper in a seawater environment. A submerged pipeline is used as the controlled structure to experimentally study the effectiveness of ECTMD. The dynamic properties of the submerged pipeline are obtained from dynamic tests and the finite element method (FEM). The optimum design of TMD with a linear spring-damper element for a damped primary structure is carried out through numerical optimization procedures and is used to determine the optimal frequency tuning ratio and damping ratio of ECTMD. In addition, the performance of ECTMD to control the submerged pipeline model is respectively studied in free vibration case and forced vibration case. The results show that the damping provided by eddy current in a seawater environment is only slightly varied compared to that in an air environment. With the optimal ECTMD control, vibration response of the submerged pipeline is significantly decreased.

In this paper, a novel pounding tuned mass damper (PTMD) utilizing pounding damping is proposed to reduce structural vibration by increasing the damping ratio of a lightly damped structure. The pounding boundary covered by viscoelastic material is fixed right next to the tuned mass when the spring–mass system is in the equilibrium position. The dynamic properties of the proposed PTMD, including the natural frequency and the equivalent damping ratio, are derived theoretically. Moreover, the numerical simulation method by using an impact force model to study the PTMD is proposed and validated by pounding experiments. To minimize the maximum dynamic magnification factor under harmonic excitations, an optimum design of the PTMD is developed. Finally, the optimal PTMD is implemented to control a lightly damped frame structure. A comparison of experimental and simulated results reveals that the proposed impact force model can accurately model the pounding force. Furthermore, the proposed PTMD is effective to control the vibration in a wide frequency range, as demonstrated experimentally.