Study On The Performance Of Sprag Clutch With Wedge Surface Modification And Optimization Of Modification Parameters

In the sprag clutch,the contact between wedge and the inner?outer ring belong to limited line contact type,stress concentration effect always occurs at the end of line contact in the wedging process,and the contact surface stress distribution is very uneven.This phenomenon will cause the low cycle fatigue life of the material at the axial position of the wedge contact surface,In particular,the plastic deformation or shedding occurs in the end position material during the wedge process.In order to solve this problem,this paper has carried out the related research on the surface modification of the wedge,overcome the end stress concentration effect on the contact surface in the wedging process,and improved the uniform distribution of the stress on the contact surface.In this paper,a single arc all phase type sprag clutch is taken as the research object and the Ansys Workbench is applied to the static simulation of the clutch,so that we can observe the stress concentration at the end of the contact surface of the wedge.We use the Hiroki logarithmic model to modify the contact surface of the wedge and the influence of the modification parameters on the stress distribution of the contact surface is studied based on the finite element method.The influence coefficient method is used to study the influence of contact surface modification on contact deformation.Based on the influence coefficient method and the wedge angle iterative algorithm,the influence of the contact surface modification of the wedge on the wedge joint lift,the inner contact angle and the external contact angle is studied,and the check of the sprag clutch is completed.The dynamic simulation of the sprag clutch under the working condition of wedging is carried out with Ansys-Lsdyna,and the dynamic parameters,such as contact force,contact stress,slip angle and joint time are extracted.The dynamic simulation of the initial modification parameters is carried out,we can observe the distribution of the contact surface stress under the peak contact force and the steady contact force,determine the necessity of the modification on the basis of dynamics.The dynamic simulation of the sprag clutch under different modification conditions is carried out to explore the effect of modification on the contact force and sliding angle and joint time.The key dynamic parameters are analyzed and selected to guide the design of the surface modification parameters.Based on the relevant conclusions about the influence of modification on the mechanical performance of the sprag clutch,the range of each modification parameter under the rated torque is determined.In order to improve the uniform distribution of the stress on the wedge surface in the wedging process,the corresponding Kriging approximate model was established by the response values of the uniform stress distribution coefficient under peak contact force and steady contact force respectively.The prediction accuracy of the approximate model is considered,and the optimization model is established.The genetic algorithm is used to optimize the contact surface modification parameters of the wedge,and the optimization results are simulated and verified.