Structural Design And Analysis Of Quasi-zero Stiffness Isolator For Car Seats

The stiffness of the car seat vibration isolation system has an important impact on ride comfort.Reducing the stiffness of vibration isolation systems is a common way to control vibration in the body’s sensitive vibration frequency range.However,it is a contradiction between reducing the stiffness of the vibration isolation system and maintaining the carrying capacity of the car seat.How to reduce the stiffness of vibration isolation and achieve lowfrequency vibration reduction under the condition of ensuring the bearing capacity of the seat has become a research direction of many scholars.As a car seat vibration isolator,a nonlinear isolator with high static stiffness and low dynamic stiffness is designed.Different from the traditional linear vibration isolator,the quasizero stiffness isolator is composed of positive stiffness elements and an Euler bar with elements.With the characteristics of quasi-zero stiffness of the isolator,low-frequency vibration isolation is achieved.Firstly,the theoretical model of negative stiffness is established.The influence of Initial position parameters on load-displacement and stiffness-displacement is analyzed.Then,combined with the theory of negative stiffness system,a theoretical model of quasi-zero stiffness system is established.And the numerical analysis results calculated by the theoretical model are compared with the results of finite element analysis.Then,based on the established theoretical model,four quasi-zero stiffness isolators for car seats are designed,which are single beam single-layer spring isolator,parallel double-layer beam single-layer spring isolator,symmetrical double-layer beam single-layer spring isolator and parallel Double beam double spring isolator.The carrying capacity and stiffness of the four isolators are discussed.Studies show that four types of isolators have quasi-zero stiffness characteristics,but the parallel double beam single-layer spring isolator is an unstable system.When the load changes slightly around the quasi-zero stiffness,the isolator will instantaneously lose stability.The remaining three quasi-zero stiffness isolators have a low first-order natural frequency.And they can reduce low-frequency vibration and have a wider vibration isolation band.Finally,the processing methods and their effects are discussed when the load changes.In this paper,load changes are divided into overloading and underloading conditions.The pre-stress of the system is adjusted by the up and down movement of the load adjustment mechanism to meet the requirements of different loads.