The Fatigue Life Prediction For Cylinder Liner Of Diesel Engine

The cylinder liner, one of the pivotal parts of combustion chamber, works withhigher thermal and mechanical loads, and due to high stress it become the mostvulnerable component in diesel engine. The failure such as cylinder crack greatly limitsdiesel engines’ durability and reliability. A detailed analysis, computation or exactevaluation on its structure and fatigue life is essential in the process of design. It ishelpful to improve and optimize the design, and then achieve a satisfactory design.Cylinder diameter enlargement currently is one of the important ways to increasediesel power, heighten power density and develop products. A certain type of dieselcylinder liner was chosen as the study subject, and an integral contact multi-fieldindirect coupling method was put forward. The temperature field, thermal&mechanical coupling fields and fatigue life were calculated by using finite elementmethod. The research work includes the following aspects.The structure and assembly relations of cylinder liner had been studied in detail. Afinite model including cylinder block, cylinder head, cylinder liner, cylinder headgasket and cylinder head bolts was established by using finite element softwareMSC.Hypermesh, avoiding the disadvantages of partial model and single componentresearches. The issues such as grid type selection and quality controlling were given adetailed distribution in paper. The model accuracy and model efficiency of thecomputation were both taken into consideration.The boundary conditions such as piston force, retightening force in bolt and heattransfer coefficient were determined by using software MSC.Adams and MATLAB.The temperature field, structural stress field, thermal stress field and thermal&mechanical stress field were calculated by MSC.Nastran, which were prepared forfatigue life estimation.Combined with related analysis results, the fatigue life for cylinder liner wasanalyzed by MSC.Fatigue. Afterwards, the contour results of fatigue life and safety factors were obtained. The most serious fatigue damages in the cylinder liner werefound at the same time. Meanwhile load reservation coefficient was put forward, whichcan be used to describe fatigue life.Finally，the contours of stress field, deformation and fatigue life of the originalcylinder liner and the enlarged one were analyzed and compared, the influence ofcylinder diameter enlargement was discussed.