Design And Analysis Of Quasi-zero Stiffness Car Seat Vibration Isolation System Based On Beam Structure

With the continuous improvement of living quality,people's requirements for carcomfortableness are also increasing day by day.The car seat vibration isolation system is crucial for the ride comfort of the car.When the car is running,various excitations from the road are transmitted to the human body through the car seat vibration isolation system,and the human body is most sensitive to low-frequency vibration,which can easily lead to physical discomfort.For the traditional linear car seat vibration isolation system,the cost of achieving low-frequency vibration isolation is to significantly decrease the stiffness of the system,which can not guarantee its bearing capacity.While the quasi-zero stiffness car seat vibration isolation system with high static stiffness and low dynamic stiffness can solve this problem well.The quasi-zero stiffness system can have a low dynamic stiffness while ensuring its bearing capacity,so that the purpose of isolating low-frequency vibration can be achieved,and the ride comfort of the car can be improved.In this paper,the positive and negative stiffness elements are designed separately using the beam structure,and parallelly forming them into a quasi-zero stiffness car seat vibration isolation system.And based on this,compliant mechanisms are added to improve its applicability.Firstly,the mechanism of applying beam structure to achieve positive and negative stiffness is analyzed,and their load-displacement relation is obtained by mathematical derivation.Then compare the analytical solution calculated by MATLAB with the simulation result obtained by ANSYS through an example,which proved the feasibility of constructing the positive stiffness element and the negative stiffness element with the beam structure.Then,the positive stiffness element and the negative stiffness element are designed separately by using the beam structure,and the influence of structural parameters of beams on their mechanical properties is analyzed.After that,the positive stiffness element and the negative stiffness element are established by selecting appropriate structural parameters of the beam,and combining them into a quasi-zero stiffness system for car seat,which the working load of the system is about the weight of an ordinary adult.Then the static and dynamic characteristics of the system are analyzed,and the relation of load-displacement and stiffness-displacement are obtained.By calculating the transmissibility of the working range of quasi-zero system and comparing it with the linear system,it is proved that the vibrationisolation performance of the quasi-zero system is obviously better than that of the linear system.Besides,the quasi-zero stiffness system has a good performance in low-frequency vibration isolation.Finally,compliant mechanisms are added to the quasi-zero stiffness car seat vibration isolation system,and the influence of compliant mechanism parameters on the mechanical properties of the quasi-zero stiffness system is analyzed.And compare it with the quasi-zero stiffness system without the compliant mechanisms,it is proved that performance in low-frequency vibration isolation of the quasi-zero stiffness system with compliant mechanisms is not as good as the quasi-zero stiffness system without compliant mechanisms,but it is showed that it requires less displacement to reach the equilibrium position and it has a larger working range.Which means the quasi-zero stiffness car seat vibration isolation system with compliant mechanisms is more stable and more adaptable.