The Study Of Design Method Of Rear Balance Suspension For Heavy Tractor

With the development of the society in China,requirements for vehicle driving comfort,especially for heavy trucks,are increasing gradually.Leaf spring balanced suspensions in heavy trucks can ensure the vehicle’s riding comfort and handling stability while meeting the requirements of improving transport efficiency.Because of its low cost,simple structure,easy maintenance,etc.,leaf spring is widely used in balanced suspension.On account of its nonlinear geometry,nonlinear contact etc.,the precise design of leaf spring becomes difficult.The development of advanced contact dynamics and CAE technology makes it possible to solve this problem.This paper takes a heavy truck as an example.According to the latest designs and applications of the rear balanced suspension,research has been done by utilizing the well-developed modern research methods on the following aspects:(1)The mathematical model of leaf spring is studied,and the calculation methods of trapezoid tapered leaf spring are verified.Then the taper-leaf spring mathematical model is established,the stiffness,strength and other calculation methods for taper-leaf spring are also studied,and then the establishing of the three-dimensional model is discussed mainly.(2)The basic analysis methods of advanced contact dynamics theory are summarized.Considering large deformation,interleaf contact simultaneously,the FEA model of one taper-leaf spring is built using Ansys based on the nonlinear finite element method.The stress and strain distribution and stiffness properties are calculated and analyzed under three conditions:clamping,fully loaded,and extremely loaded.(3)The taper-leaf spring of balanced suspension is optimized.First,under the design requirements of balanced suspension,structure parameters of the spring are chosen and optimized using Matlab.To determine the appropriate structure parameters of the spring,the curve height and working stroke are decided considering parameters such as the specific stress and stiffness to decrease the empty loaded frequency of the spring and improve the riding comfort.Finally,the structural properties of the original structure of balanced suspension’s spring and the optimized one are compared,the bench test results show that optimization design of the leaf spring meets the design requirements,and the model is highly accurate.The elastic deflection and stiffness are measured through the property experiments of the spring.The simulation results and experimental results are identical,which verifies the accuracy of the leaf spring finite element analysis model and the analysis method.(4)Basic research on the performance of the rubber parts in the suspension system is done.Since the strain-stress relation of rubber parts is relatively complex,metal plates are usually inserted into rubber parts in order to increase their performance like stiffness.The rubber-metalplate structures are studied by finite element methods and ductile mechanics,strain changes of the rubber parts under certain loads are analyzed.Based on the real service condition,the influences of the rubber bearing on lead spring supports are analyzed.Served as the connection between leaf spring supports and supports of the balanced suspension,the rubber bearing influences the supports greatly with its stiffness and strength.The nonlinear constitutional model of the rubber and the complex contacts between rubber bearing and leaf spring supports make it difficult to analyzed the strength of the rubber bearing and leaf spring support.Based on multiple bench tests and nonlinear analysis using Abaqus,strength analysis is conducted accurately considering the material properties of the rubber parts.