The Anti-fatigue Design And Life Prediction Research Of Steel Piston Based On Thermal-mechanical Coupling

With the diesel engine continued to the development of high power density direction, asthe heart of the diesel engine, the piston’s working conditions become worse, so the pistonmaterials, structures and processes have a breakthrough. To address the problem on the basisof finite element analysis and anti-fatigue design theory, to carry out the steel piston thermal -structural coupled analysis, anti-fatigue structural design and fatigue life prediction, madeuseful explorations in the steel piston structure-anti-fatigue.On the basis of the establishment of the steel piston three-dimensional geometric modelusing the finite element software HYPERMESH three-dimensional model of the steel pistongeometry clean-up and determine a reasonable solution of the mesh, material properties aredefined to establish the boundary conditions of the heat load, mechanical load boundaryconditions, thermal-mechanical coupling boundary conditions, using the finite elementanalysis software ANSYS, and then model the heat load, mechanical load, thermal--mechanical coupling calculation to obtain the steady-state temperature field of steel pistontemperature contours, temperature gradient cloud, cloud picture of the heat flux, heat loadunder the action of stress and deformation, stress and deformation under mechanical load,stress and deformation under the heat - structure interaction, through the establishment of thesteel piston reference point of stress and deformation of a column chart, have a dangerousposition under different load of the steel piston, laid the foundation for the next anti-fatiguestructural design and fatigue life prediction.Piston design is necessary to ensure safe durable resistance to thermal load andmechanical load, but also seeks the minimum weight. Light weight main piston depends onthe structure and size of the rational choice, due to the orthogonal design method can be less time to calculate the optimal solution, this article anti-fatigue structural design in the wrongpiston bigger changes under the conditions of the cavity of the piston cooling oil averageheight, and thickness at the top and pin spacing of three structural dimensions defined designvariables controlling factors, and set the level of three values of the various factors, usingorthogonal table L₉（3⁴） arranged in 9 groups of experimental program to optimize thedesign, and ultimately determine the design of anti-fatigue program to reduce piston mass,reducing the danger point stress and improve resistance to fatigue the purpose. And the factorsof poor value, calculated according to the above results to construct the F statistic to generatethe orthogonal variance analysis, significant sex made a comparative study the effect ofvarious factors, the continued weight loss for the steel piston, anti-fatigue ability to furtherimprove to provide a reference.Through the exploration of structural fatigue analysis theory, select the fatigue lifeestimation method of limited life method for fatigue life prediction, and the nominal stressmethod based on the material SN curve as a criterion to the piston fatigue life estimates.Fatigue life analysis software FE-SAFE, geometric characteristics of the input structure, thefatigue load information, material fatigue properties of three information in order to achievethe rated conditions, anti-fatigue structural design of steel piston thermal loads, mechanicalloads, thermal-fatigue life cloud structure interaction and the establishment of anti-fatiguestructural design of steel piston rated conditions of the load of the fatigue life of column,made useful explorations on the fatigue life prediction of steel piston.