Study Of The Mechanical Properties Of The Leaf Spring Based On ALGOR Numerical Simulations

Leaf spring is an important elastic component in suspension system,predicting of the mechanical properties and fatigue life is the key issue for the design,so it is often necessary to carry on the exact calculation of the leaf spring.In this thesis,the parameterized CAD model of multi-leaf spring was built using Autodesk Inventor software,and the strength and stiffness properties of leaf spring are researched using ALGOR Nonlinear MES module.The fatigue life was predicted using ALGOR-Fatigue Wizard.Based on the design requirements and CAE results,lightweight for the leaf spring was conducted.To simulate the structure characteristics of the leaf spring,simplifications and the boundary equivalence of the leaf spring were put forward.The largest pre-tightening force and reacting force produced during the assembly process were calculated.The pre-tightening force characteristics changing with the assembly process was studied.By simulating loading and unloading process of the leaf spring,the characteristics of its stiffness and stress characteristics were obtained.For the structural stiffness of theoretical calculation and simulation,the results were compared.The method how to speed up the convergence of a nonlinear computation for the simulation was investigated.Fatigue life characteristics is one of the key indicators in the design of the leaf spring.The fatigue life characteristics was studied through stress-based fatigue analysis under varied amplitude loading which was obtained with the transient analysis methods.The method of obtaining S-N curve is proposed,and the Goodman correction and Gerber correction was compared for their differences.The influence of surface processing factors on the fatigue life was considered.Based on the simulation results,a parametric CAD model for the leaf spring was created with Inventor.By importing into ALGOR for analysis and with consideration of vehicle arrangement,the leaf spring can be optimized.Results show that pre-tightening force increases with decreasing the distance of the assembly.The pre-stress results obtained by theoretical calculation and simulation are the same.Under the full-load loading,the maximum stress at each plate occurs near the U-bolt which is consistent with the real situation and the strength requirement is satisfied.In addition,the change of structure stiffness is less related with loading.Comparing theoretical calculation results for stiffness,the simulation results are almost the same with the tolerance within 2%.The minimum fatigue life occurs at the location of the maximum principal stress under varied load,and the Goodman correction is more reliable.According to the simulation results,the thickness parameter of each plate was optimized and the overall weight of leaf spring was reduced by 5 percent.