Fatigue Life Analysis And Structural Optimization Of Connecting Rod In A Gasoline Engine

The connecting rod is an important moving member of the crank connecting rod mechanism.The engine can run normally without the connecting rod with reasonable structure and stable performance.When the engine is working,the connecting rod is connected with the piston pin to convert the reciprocating inertial force caused by the reciprocating linear motion of the piston into the rotating inertial force of the crankshaft.The unique importance of the connecting rod and the working environment must determine the connecting rod Subjected to alternating tensile and compressive stresses,the connecting rod must have sufficient structural strength and fatigue resistance.Firstly,it analyzes the movement and overall stress of the connecting rod during work,and makes a theoretical basis for the load calculation of the connecting rod.It further analyzes and calculates the structural strength of the engine connecting rod,and at the same time completes the connecting rod in the working process.Study on the dynamic characteristics of the link and the fatigue characteristics of the connecting rod,and finally optimize the lightweight design of the link,The result is a connecting rod that is not only reliable in performance,reasonable in structural layout,but also capable of meeting a significant reduction in mass,a small size,and a significant reduction in stress concentration at the transition area between the large and small connecting rods and the shaft.This article takes the connecting rod assembly of the 2V86 gasoline engine developed by the team as the research object,and adopts large-scale general 3D modeling software for connecting rod assemblies such as connecting rod body,connecting rod cover,upper and lower bearing bushes and connecting rod bolts according to the two-dimensional drawings Pro / E carries out the physical digital simulation.Then use the finite element preprocessing software Hypermesh to mesh the connecting rod components,and then calculate the stress,deformation and fatigue strength of the connecting rod under representative working conditions.Calculation under force and bolt preload force.The finite element software ABAQUS was used to perform a finite element analysis on the connecting rod,and the stress distribution of the connecting rod under several typical working conditions was obtained.The analysis results show that the connecting rod completely meets the structural strength requirements under these several working conditions.No structural failure will occur.Further modal analysis,buckling analysis,andfatigue life analysis of the connecting rod provide a basis for the lightweight optimization of the connecting rod.After optimization,the structural displacement is increased by14.8%,the maximum stress is increased by 28.5%,both within the allowable value range,and the volume is reduced by 10.3%.Topology optimization provides designers with the idea of reducing weight,that is,from the connecting rod head and shaft Reducing materials at the joints can save materials and reduce weight,which can effectively reduce the inertial force of the connecting rod and improve the stability of the engine operation.