Design Of Quasi-zero Stiffness Vibration Isolator And Analysis Of Sound Insulation Performance

In recent years,the rapid development of high-speed railway construction has greatly facilitated people’s life and travel.With the increase of train operation speed,the problem of noise inside high-speed trains has also attracted more and more attention.High-speed train floors are connected with bogies,so the noise generated by vibration is large.In order to solve the problem of high-speed train floor sound insulation,this paper designs a quasi-zero stiffness vibration isolator,which is placed in the middle of the high-speed train floor to improve the overall sound insulation performance of the floor.The research content includes the following parts:Firstly,a disc spring with negative stiffness is connected in parallel with two spiral springs with positive stiffness to form a quasi-zero stiffness system.The pre-tightening force of the upper spring through the nut can keep the system in a quasi-zero stiffness state,and adjust it as needed.The structural model of the quasi-zero stiffness vibration isolator is designed and assembled.The load-displacement curve of the system can be obtained through static analysis to determine that the system has the characteristics of high static stiffness and low dynamic stiffness at the equilibrium position.Through dynamic analysis,the vibration isolation characteristics of the quasi-zero stiffness system can be obtained.The dynamic equation of the quasi-zero stiffness system is theoretically established,and the amplitude-frequency characteristic curve of the system is solved by the harmonic balance method,and the dynamic simulation analysis is performed.The time domain and frequency domain response of the system are obtained by dynamic simulation analysis.Analysis of the force transmission rate at each frequency shows that the system has relatively good vibration isolation performance in the frequency range greater than 50 Hz,which provides a theoretical reference for subsequent experimental analysis.Next,the sound insulation performance of the quasi-zero stiffness vibration isolator is analyzed.The evaluation method of sound insulation performance is introduced.The sound insulation theory of single-layer and double-layer panels are respectively analyzed.The finite element equivalent model of the car body floor was established.Through the finite element software,the sound insulation of the two floor models installed with the existing vibration isolator and the quasi-zero stiffness vibration isolator were tested,and the sound insulation curve in the 50 ～ 1000 Hz frequency band was obtained.It is obvious that the quasi-zero stiffness vibration isolator has better sound insulation performance than the existing vibration isolators,and it meets the theoretical results and design requirements.Finally,an experimental platform was built for experimental design.Some components of the quasi-zero stiffness vibration isolator were printed using 3D printing technology.Choose suitable coil springs to matah disc spring’s stiffness.The nut was used for pre-tightening and the assembly model of the quasi-zero stiffness vibration isolator is obtained.The statics experiment and dynamic experiment were done respectively for the quasi-zero stiffness vibration isolator.The static experiment obtained the loaddisplacement curve of the system,which proved that it has high static and low dynamic characteristic.In the dynamic experiment,a vibration exciter was used for vibration testing.The time domain and frequency domain responses of the system are obtained.The calculated acceleration transmission rate at each frequency is basically consistent with the simulation results,which proves that the quasi-zero stiffness vibration isolator has good vibration isolation performance.