Fatigue Strength Analysis And Structural Optimization Of The Connecting Rod In A Diesel Engine

A connecting rod is an important structural component in internal combustion engines,which transfers the pressure power from the piston to the crankshaft and converts the reciprocating motion of the piston to the rotary motion of the crankshaft.A connecting rod mainly bears alternate loads such as compression,stretch and bending.Therefore,the fatigue strength of a connecting rod should be high enough and its mass should be as small as possible.In this paper,the fatigue strength of the connecting rod in a diesel engine is calculated and its structure is optimized based on the finite element analysis.Firstly,according to the design requirement and the force analysis,the basic design size of the connecting rod is determined.Secondly,the stress distribution of the connecting rod under different conditions is obtained by finite element analysis using software ANSYS Workbench 14.According to the analysis results,the position of the oil hole in the small head of the connecting rod is modified.By determining the transition fillet radius between the small head and the rod body and the chamfering radius of the cross section near the small end as the design variables,and limiting the mass of the connecting rod,the optimization is carried out to obtain the minimal equivalent stress.After the optimization,the maximum equivalent stresses of the connecting rod in both the maximum tensile condition and the maximum compression condition are reduced.The fatigue safety factor is improved by 5 %,and the mass of the connecting rod is decreased by 2.8%.These results have met the design requirements.