The Multi-axial Fatigue Life Prediction And Research Of The Cylinder Cover Based On The Transient Dynamics

Cylinder cover as one of the key parts of the diesel engine, work in the process ofbearing force of the bolts, the gas pressure and the heat load of the periodic function, thestress、Strain and deformation of the occurrence of periodic change. Along with thestrengthening of diesel Engine, multi-axial fatigue life problem gradually becomes theresearch hot spot Aiming at this problem, this paper takes a V diesel engine as an example,one cylinder cover of a whole cylinder as the research object, on the basis of the dynamicproblem and multi-axial fatigue life prediction theory, established the finite element model ofcylinder cover, carried out the dynamic response analysis of cylinder cover and made themulti axial fatigue life prediction. To make some explorations on various calculation methodsand influencing factor in the research of the cylinder multi-axial fatigue life prediction, thiswill provide some support for more accurate prediction of cylinder head of the multi-axialfatigue life.Application of modeling software made the three-dimensional geometry entity model ofcylinder head, cylinder liner, cylinder pad, body, bolt and other parts, then import them intothe professional grid software and finish the material, attribute set on each part, Under thepremise of ensure the accuracy of the calculation results, make some certain simplification forvarious parts of the structure and choice reasonable unit type and unit size to grid. Defined the5 pairs of contacts between the cylinder head and cylinder gasket, cylinder head bolt, bodyand cylinder pad parts and so on, simulate the working conditions of the cylinder cover,loading the constraint, bolt force and gas pressure. Complete cylinder cover combinationstructure finite element model for transient dynamics. Using finite element analysis software, make the transient dynamics by direct integralmethod in the integral method, get and analysis each node displacement and stress timehistory on the cylinder cover, get the displacement and strain time history comparison chartbetween different position on the cylinder cover. This will not only provide the theory basisfor the cylinder cover design and improvement, but also provide data for the multi-axialfatigue life prediction.Let the transient dynamics results into the fatigue life calculation software. Definematerial properties, prepare the LDF file, choose the Brown-Miller method in critical planemethod for multi-axial fatigue life calculation, prediction of multi-axial fatigue life of thecylinder cover, get the multi-axial fatigue life distribution and safety coefficient map of thecylinder cover, introducing the Weibull function life reliability calculation model, make themulti-axial fatigue life reliability research in a given design life expectancy.Through the cylinder cover fire face, upper surface in different roughness undermulti-axial fatigue life was investigated, found improved cylinder head surface machiningquality is to improve the fatigue life of a measure, The follow-up analysis model taking intoaccount the roughness factor. Study on the cylinder head in three kinds of multi-axial fatiguelife calculation model of fatigue life of distinction, found the Brown-Miller method than thenormal strain model and shear strain model is more suitable for the cylinder cover ofmulti-axial fatigue life calculation. At the same time on the cylinder head in a conventionaluni-axial calculation model of fatigue life, contrasting results need further verification test.