| The connecting rod is one of the important transmission parts in the automobile engine.The quality of the connecting rod has an important influence on the energy conversion of the engine and the driving safety of the vehicle.Because of its high material utilization rate,good mechanical properties,high forged precision,less production process,low production cost and so on,powder forged connecting rod has good prospects for development.Because the force of the connecting rod is very complicated,so it need have sufficient strength and stiffness.At the same time,under the influence of the periodic load,the connecting rod is prone to fatigue failure,affecting the normal work of the engine.Therefore,the strength and fatigue life is an important part of connecting rod design.This paper is based on the a certain type powder forged connecting rod developed by a company.The finite element model under typical engine condition and the fatigue life prediction model of connecting rod were built.Through the FEM model and fatigue life prediction model,the stress distribution and the factors that affect the fatigue life of the connecting rod were studied,especially for the influence of geometrical asymmetry on the strength and fatigue properties.Based on software ABAQUS,the static force finite element analysis model of powder forged connecting rod is established.The stress distribution and deformation of the connecting rod were obtained by finite element analysis of the force of the connecting rod under three typical working conditions.The effects of two different loading modes on the stress distribution of the connecting rod were compared,the two loading modes were to apply the load directly to the piston pin and apply the load directly to the bushing.According to the results of finite element static force analysis,the fatigue life of powder forged connecting rod was analyzed and predicted by Fe-safe software.The effects of different fatigue algorithms and mean stress correction methods on the fatigue life prediction of connecting rod are compared.According to the failure pieces and fatigue failure position of the powder forged connecting rod provided by thecompany,the stress-Based Brown-Miller algorithm and the Morrow mean stress correction method were used to establish the fatigue life prediction model.The effects of the surface roughness and material strength on the fatigue life and fatigue safety factor of the connecting rod were studied.In view of the fact that the geometric asymmetry that may occur in the actual forging process of powder forged connecting rod,the finite element analysis model and fatigue life prediction model of connecting rod under the case of geometric asymmetry were established,and the influence of three different geometric size deviations on the stress distribution and deformation of the connecting rod and the influence of the geometric asymmetry of the connecting rod on the fatigue life and fatigue safety factor of the connecting rod were analyzed. |
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