Research On Damping Performance Of Inerter Nonlinear Energy Sink With Tri-stable Characteristics

As the world’s earthquake disasters bring more and more serious losses to human beings,the demand for additional substructure damping control technology is more urgent in various countries.The additional substructure damping control technology is to add a substructure to the main structure.under the action of external excitation,the substructure exerts a force opposite to the vibration direction of the main structure to the main structure,thereby reducing the seismic response of the structure.Based on the reference to the domestic and foreign additional substructure damping control technology,this paper finds that compared with other linear shock absorbers,the nonlinear energy sink can effectively absorb and dissipate the energy of the main structure in a wide frequency band,which makes it have strong frequency robustness.The reason why it is not widely used in the field of structural vibration is that although the advantages of nonlinear energy sinks have been widely recognized,large additional mass blocks need to be introduced into nonlinear energy sinks.The emergence of inerter provides an effective method for greatly reducing the additional mass required by the damping device.On this basis,this paper proposes an inertial nonlinear energy sink with tri-stable characteristics,and studies its damping control performance and robust performance under single-degree-of-freedom and multi-degree-of-freedom main structural systems,the main contents are as follows:In this paper,an inertial nonlinear energy well model with tri-stable characteristics is proposed and the system dynamics equation is obtained according to its mechanical model.Aiming at the typical single-degree-of-freedom main structure model,the standard DE algorithm is used to optimize the structural parameters of the three basic types of inerter nonlinear energy sinks.On the basis of parameter optimization,the vibration control performance of the three basic types is compared and analyzed.With the analysis of the influence of nonlinear restoring force system parameters l1,l2,l3,L and Ks on the system characteristics,it is found that the parameters l3 and L have a great influence on the system characteristics.For the typical single-degree-of-freedom main structure model,the standard DE algorithm is still used to optimize the structural parameters of TMD,cubic NES and inertial NES,under the condition of parameter optimization,the robust performance and the damping control performance of each control mode is compared and analyzed,it is found that the inertial NES has better damping control performance than cubic NES and better frequency robustness than TMD.In order to analyze the damping control mechanism of each control mode,the time-frequency diagram of seismic response of each system is drawn by wavelet transform,Phenomenon about that in addition to the 1:1 main resonance behavior near the fundamental frequency and the main structure,the inertial NES also produces instantaneous superharmonic internal resonance trapping behavior and instantaneous subharmonic(also known as subharmonic)internal resonance trapping behavior at high and low frequencies respectively is found,this reveals the reason why the inertial NES has excellent damping control performance and good damping robustness.Although the damping control performance of the inertial NES in the multi-degree-of-freedom system is degraded compared to the single-degree-of-freedom system,it has a certain damping control effect on the main structure is obtained by installing a inertial NES in the isolation layer of a 20-story Benchmark model.The inertial NES still has excellent damping robustness in the case of multi-degree-of-freedom system is obtained by analyzing the damping performance of the inertial NES when its own parameters change by ± 20%and the stiffness of the main structure changes by ± 20%.