Research And Optimization Of Interference Assembly Reliability Of Connecting Rod Bushing

The engine connecting rod bushing is a joint part connecting the small end of the connecting rod and the piston pin.The reliability of the interference fit between the connecting rod bushing and the connecting rod small end hole is a prerequisite for reliable engine operation.Fretting and loosening occur during the reciprocating motion of the rod;it is also necessary to ensure that the equivalent stress generated by the interference assembly of the connecting rod bushing meets the strength requirements and prevents its plastic deformation failure.Therefore,the analysis of the contact pressure and equivalent stress generated by the interference assembly provides a theoretical basis for the reliability research and optimization of the interference assembly of the connecting rod bushing.This article takes a certain type of engine connecting rod bushing as the research object,and the combined cylinder interference fit theory,crank linkage dynamics theory and ABAQUS finite element simulation were used.Analyze the variation of contact pressure and equivalent stress under different interference assembly methods for the interference,the elastic modulus of the material and the wall thickness that affect the reliability of the connecting assembly of the connecting rod bush Surmount the assembly method and conduct experimental verification.The research content and results of this article are as follows:1.By analyzing the variation of the contact pressure and equivalent stress of the connecting rod bushing interference assembly method on the connecting rod bushing interference fit surface,the advantages and disadvantages of different interference assembly methods are obtained;the equivalent stress at different press-fitting stages is analyzed The change of the pressure and the effect of the pressing speed on the equivalent stress and the pressing curve at the beginning of the pressing process give a reasonable value of the pressing speed.2.Analyzed the influence law of the three factors,and obtained the value range of the influence factors;the contact pressure of the interference fit surface of the connecting rod bushing increased with the increase of interference,material elastic modulus and wall thickness;The force increases with the increase of the interference and the elastic modulus of the material,and decreases with the increase of the wall thickness.3.Optimize the interference assembly method of the connecting rod bushing.After the optimization,the average contact pressure on the mating surface increases and the equivalent stress decreases.The fitting rate of the trial-produced connecting rod bushing and connecting rod small-end hole exceeds 85%,and the interference assembly is effective;the average maximum extrusion force of the extrusion experiment is 64.61 kN,which meets the technical requirements of the interference assembly and the error of the simulation result is 5.58%.It can prevent the connecting rod bushing from loosening and failing,and provides a basis for connecting rod bushing design and interference assembly design.