Study On The Performance Of New Quasi Zero Stiffness Vibration Isolators

The quasi-zero-stiffness structure with positive and negative stiffness components can provide excellent low frequency/ultra-low frequency vibration isolation performance for vibration isolation systems while maintaining its bearing capacity.Based on the characteristics of quasi zero stiffness structures,passive vibration isolation technology with quasi-zero stiffness has received widespread concern and rapid development in last years.It has been applied in engineering and achieved good results.In this paper,a new Euler beam with bending deformation quasi zero stiffness isolator(EB-QZS isolator)and X-combined nonlinear isolator are proposed through geometric nonlinear innovative design and research.The main tasks are as follows:Euler beam is often used in quasi zero stiffness(QZS)isolators because of its bistable characteristics.However,the bistable characteristics often cause the vibration isolation system to lose a considerable part of the working range,which makes the isolators using Euler beam as the main components have problems such as instability and low utilization of the working range.Therefore,in order to solve the above problems,this paper adjusts the position and size of the QZS range of the structure by coupling the linear spring with the curved Euler beam,and by limiting the displacement of a certain place on the beam,so that the vibration isolation system can have the QZS or positive stiffness characteristics to improve the performance of the isolator when the Euler beam changes from the first steady state to the second steady state.The QZS vibration isolator was theoretically studied and analyzed by using the simulation software COMSOL Multiphysics.Meanwhile,the vibration isolation performance of passive vibration isolator of EB-QZS isolator is studied by COMSOL Multiphysics and carry out the parameter study.The displacement transmissibility was used as the evaluation standard to study its vibration isolation performance,and the vibration experiment is carried out to verify the correctness of the theoretical research results.Secondly,X-shaped structure or similar structure(scissors structure,Z-shaped structure,etc.)widely exist in nature,which enables organisms to better support their bodies and maintain good stability in the process of movement,especially in response to the vibration or impact brought by the external environment.Therefore,some bionics scholars apply it to the isolator to improve the vibration isolation performance.In this paper,a new X-combined nonlinear structure is designed by coupling X-shaped structure and inclined springs.The negative stiffness in X-shaped structure is eliminated by using the nonlinear positive stiffness of inclined springs,and the nonlinear vibration isolation range and working stability of the structure are improved.It also increases the designability of vibration isolation structure.And construct an X-combined nonlinear isolation platform using three X-combined nonlinear isolators.In the research,the dynamic equation of X-combined nonlinear structure is provided by utilizing Hamiltonian’s principle,and the nonlinear dynamic equation is solved by harmonic balance method.Similarly,the vibration transmissibility is used as the evaluation standard to study its performance of vibration isolation,and investigated the effect of some vital parameters on the isolation performance of the structure.What’s more,the multi-rigid body simulation software Adams is used to corroborate the correctness of theoretical results.Finally,the physical structure is designed and the vibration experiments are proceeded to validate the correctness of the theoretical and simulation research results.