The Analysis Of Connecting Rod And Connecting Rod Bolt Strength On Gasoline Engine

Finite Element Method has been applied widely in Internal-Combustion Enginedesign for its advantage. There are two classes of aims of using Finite ElementMethod in Internal-Combustion Engine project：One is to analyze the structure ofInternal-Combustion Engine, find out the reasons why the parts been damaged，pointout the unsubstantial positions, and advance an improved way; the other is structuredesign. In the process of structure design, some possible structure can be analyzed andcalculated with Finite Element Method in advance, through analyzing and comparingthe calculating results, the best one can be chosen.Connecting rod is an important part of Internal-Combustion Engine, but at sometime, it is unsubstantial. At present, the Finite Element Method has been used widelyin designing and analyzing it. In engine, Connecting rod connect piston pin andcrankpin directly, the contact force is transferred by interface, so the force state ofConnecting rod is related strongly with piston pin and crankpin. Since long before, thecontact has been a difficult problem in Finite Element Analyze. In traditional FiniteElement Analysis, the contact is predigested for avoiding contact problem.In this paper, the connecting rod of a Q01-gasoline is studied. In the study, themodel is built through contact. Because of the affection of piston pin and crankpin,the3-D Finite Element Analysis model contains piston pin and crankpin, and it wasbuilt on the base of their true structure. Through the study about the connecting rod inFinite Element Method, the stress and intensity are gained, and the results tested byexperiment are accredited. It can be found that the reliability was increased throughoptimum design.The distributing of contact forces which are generated either by the contact ofpiston pin and the bushing of the small end or by the contacts of connecting rod andjournals bearing shells are gotten through analyzing these contacts.(figure1) This isdifferent from the rules that interface distribute along the shaft and show a parabola.Traditional force boundary conditions of interfaces of holes and shafts are accordingto the distributing of oil film press in limited extent (figure2). So we have reasons todoubt the traditional method.It is difficult to compute the stress distribution of a working connecting rod withnormal method, so an effectual Finite Element Analysis model was constructed. In this model, pre-tension was added on locking bolt through building pre-tensionelements on locking bolts. For ensuring the veracity of solving result, many effectingfactors were considered, including the interference of connecting rod journals andbearing shells, and the actual working condition can be simulated.With this computation, the puzzle of analyzing and computing the stresscontributing of connecting rod bolt can be resolved, therefore, the stress contributionand intension were gotten. The craftwork of tighten moment of connecting rod bolthas been adjusted, which cut down the largest stress during the working process andimprove the veracity of connecting rod bolt.