Study On Dynamic Characteristics Of The Double-diamond Bionic Vibration Isolation System With Inerter

Vibration is a common physical phenomenon in nature and human social activities.In most cases,vibration will cause negative effects.In this paper,two integrated bionic passive vibration isolation systems are proposed based on double-diamond bionic structure and inerter,namely series double-diamond bionic vibration isolation system with inerter and parallel bionic double-diamond vibration isolation system with inerter,aiming at the problems of low frequency vibration isolation performance,narrow vibration isolation band and large additional mass of passive vibration isolation system.In order to analyze the low frequency vibration isolation performance and effective vibration isolation band of two vibration isolation systems,a nonlinear dynamic equation is established by using Lagrange equation,and a set of algebraic equations of amplitude-frequency response are obtained by harmonic balance method.Then,the displacement transmissiveness of the system is obtained by using Newton-Raphson iterative solution of the algebraic equations of amplitude-frequency response.According to the abnormal line segment in the displacement transfer curve of a series doublediamond bionic vibration isolation system with inerter,the time domain response of the system is obtained by using the fourth-order Runge-Kutta numerical method in order to analyze its stability.Finally,in order to analyze the vibration isolation performance of the bionic vibration isolation system proposed in this paper,three comparison models are established for comparative study.The results show that:1)In a specific frequency band,the dynamic characteristics of the two vibration isolation systems are adjustable and designable.By adjusting platform mass m0,spring stiffness parameters(k1、kh、kv),damping parameters(c1、ch、cv),Angle a and inertial coefficient b,the displacement transfer characteristics of the two vibration isolation systems can be changed to achieve a wider frequency range and better vibration isolation performance.2)The introduction of inertial vessel makes the two vibration isolation systems have an anti-formant in addition to two formants in the whole frequency domain.In the series double-diamond vibration isolation system with inerter,the anti-resonance is after the second-order resonance.However,in the parallel double-diamond bionic vibration isolation system with inerter,the anti-resonance is located after the first or second resonance,which depends on the choice of inertial coefficient b.When the excitation frequency is close to this frequency,the vibration isolation performance of the system can be improved by about 10 dB3)In the series double-diamond bionic vibration isolation system with inerter,under the specific inertial coefficient,the second-order resonance frequency will be close to or coincide with the first-order resonance frequency,so that there is only one resonance peak,which further broadens the valuable frequency range of vibration isolation.4)When kh ≤ 1.78 × 106 N/m,the unstable motion of a series type double-diamond bionic vibration isolation system with inerter can eliminated nearΩ=0.5.To sum up,introducing the inertial vessel with smaller additional mass into the nonlinear bionic vibration isolation system can make the system have better vibration isolation performance and wider effective vibration isolation band.The proposed bionic vibration isolation system with double diamond shape containing inertial vessel provides a new solution for vibration control in practical engineering.