Research On Parabolic Equal Stress Taper Leaf Spring For Suspension System

The performance of vehicle suspension system is closely related to riding smooth and comfort.With the implementation of the policy of automobile lightening,few-chip parabolic leaf spring has gradually attracted the attention of experts and manufacturers in the field of suspension research.Considering complicated loading conditions for the end of first-chip and improving intensity of leaf spring,it is necessary to adopt the structure of few-chip root-intensive parabolic leaf spring with non-isomorphic for the end part.At present,however,for the design of few-chip parabolic leaf spring,designers usually adopt the method of“experience” and “repeating test” combination ways,or repeatedly amend simulation results by using CAE finite element software to meet the design requirements,there has not been given accurate analytical design method for few-chip parabolic leaf spring,and it can’t meet the design and production requirements of digital factories.In this paper,some research was conducted,aiming at the problems of static characteristics calculation and design for parabolic leaf spring,the innovations were as follows:(1)Based on the mechanics model of single chip parabolic leaf spring,combining Castigliano second theorem,deflection and stiffness calculation formulas were set up.According to the endpoint force and the thickness change rule,the stress formula was established for it.Stiffness,deflection and maximum stress calculation formulas for non-isomorphic leaf spring were built by the relationship of stiffness and load between few-chip and single chip spring.And on this basis,stiffness,deflection and different position’s stress calculation formulas for few-chip root-intensive parabolic leaf spring were founded.(2)According to static characteristic calculation formulas of few-chip root-intensive parabolic leaf spring,and combine the design requirement,single-chip root equivalent thickness calculation formula was instituted,and then set up the root thickness and the number of chips.Based on its stiffness calculation model,the design method of horizontal length for root intension part was established,and then the thickness of any section for each chip leaf spring was built.From the assembly camber under the free state,the design method of free camber for each chip leaf spring was founded.(3)Based on static characteristic calculation formulas of few-chip root-intensive parabolic leaf spring,changing laws impacted on deflection,stiffness and stress for its were analyzed under different changing scopes of root thickness,parabolic thickness ratio,root diagonal thickness ratio,elasticity modulus of material and end load,which had guiding significance of optimization design for few-chip root-intensive parabolic leaf spring based on the stiffness requirement and the stress constraint condition.A sample of few-chip root-intensive parabolic leaf spring was designed for testing the performance of it by using microcomputer controlled hydraulic spring pressure testing machine,the load-deformation curve was acquired,and verified the stiffness and camber of leaf spring.The results showed that relative deviations meet the requirements of engineering design accuracy,which indicates that the design method of few-chip root-intensive parabolic leaf spring is correct and reliable.This study has important theoretical guidance significance and engineering application value for the design and performance improvement of the few-chip parabolic leaf spring.