Research On Matching Of The Leaf Spring With Shock Absorber For Heavy Truck Suspension System

Leaf spring and shock absorber are the important component parts of heavy truck suspension system.By preventing road shocks from being transmitted to the vehicle frame,they can improve vehicle ride comfort and driving safety.Therefore,reasonable matching of leaf spring with shock absorber and designing a good suspension system are of great significance for improving vehicle ride comfort.However,damping matching which is affected by the precise calculation of leaf spring equivalent damping is the key problem to shock absorber design.So far,there is no effective way for the matching and designing of leaf spring with shock absorber.They used to be designed by the method of “experience and trial”,which is expensive,unreliable and unable to meet the rapid development of the vehicle industry and the requirements of comfort by people.This paper takes a heavy truck as research object and does some research about the matching and designing of leaf spring with shock absorber.The innovations are as follows:(1)According to two degree of freedom vibration model of 1/4 vehicle suspension and the random vibration theory,taking vehicle vibration acceleration mean square value and wheel dynamic load mean square value as the target function,a mathematical model of optimal damping ratio of suspension respectively based on ride comfort and driving safety was established,and then,integrating ride comfort and driving safety,a mathematical model of optimal damping ratio of suspension was established by the golden section method.(2)According to the theory of mechanics of materials,the monolithic equivalent model of multi-leaf spring was established by using the same deformation conditions of leaf spring.(3)Based on the quarter vehicle model and random vibration theory,the mathematical model of suspension dynamic deflection and vibration velocity were established.Based on this,the equivalent damping of leaf spring under certain work condition was obtained by analyzing and processing the load and deformation array data of leaf spring loading-unloading test.Then,combining the optimal damping ratio of suspension and equivalent damping ratio of leaf spring,the optimal damping ratio of shock absorber was concluded,and then,according to the smoothness-to-safety ratio and two-way ratio of shock absorber,the mathematical model of velocity characteristics of shock absorber was established.(4)According to elastic force theory,the deflection of throttle slice under the localdistribution of variable load is studied,and the formula of elastic throttle-slice bend deformation are created based on the shape of boundary conditions and continuity conditions.Using the formula of elastic throttle-slice bend deformation and the hydrodynamics theory,optimum design method of the shock absorber throttle valve parameters was established.The finite element analysis software ANSYS simulation and the leaf spring stiffness test proved that the designing method of leaf spring is correct.Simulation by Matlab/Simulink and the vehicle riding comfort test proved that the matching and designing method of leaf spring with shock absorber is correct.It can effectively reduce the body vertical vibration acceleration and improve ride comfort.The research is of extremely significance and practical application value for the design of heavy truck suspension system.