Thermal-mechanical Coupling Analysis And Fatigue Life Prediction Of Plate For The Wobble-plate Diesel Engine

The wobble—plate diesel engine is a new form of internal combustion engine. It has avolume of advantages such as high power density, compact structure, small vibration, lownoise and so on. The wobble plate is one of the most important components of thewobble—plate diesel engine which working in a very terrible environment and bearing avery large heat load and mechanical load. The wobble plate directly affects the reliabilityand service life of diesel engine. Therefore, we must put the wobble plate on the finiteelement simulation analysis to verify whether the structural design is reasonable or not, andprovide the basis for future optimization and improvement.Import the three-dimensional solid model of the wobble plate and Z-axis to ANSAsoftware to clean up and simplify the model, and divide into grids, set materials relatedparameter to obtain a finite element model of the wobble plate and Z-axis for below finiteelement calculation.First, calculated the temperature field of the wobble plate. The plate of theWobble-Plate Diesel Engine’s structure and motion are different from the traditional piston.The piston doing reciprocating motion, while the wobble plate doing complex nutationalmotion. This paper uses AVL BOOST software simulation to get the temperature curve andthe heat transfer coefficient curve in the cylinder, and refers to the empirical formula of thetraditional piston to calculate the boundary conditions of the plate. And get the boundaryconditions of the cooling oil cavity based on the previous work. Using the finite elementmethod to calculate the wobble plate’s temperature field, and obtains wobble plate’stemperature field distribution contour cloud and temperature gradient field contours cloud.Then, calculating the Wobble plate’s thermal stress, get the thermal stress distribution contour cloud and thermal deformation distribution contour cloud.Secondly, in this paper, I did the finite element calculation at the working condition ofthe maximum gas explosion pressure, and got the equivalent stress distribution nephogramand displacement distribution cloud of the plate. The results show that the equivalent stressis in the range of the material’s yield strength and tensile strength. Then put the temperaturefield on the wobble plate, and did the thermal-mechanical coupling calculation, obtained theequivalent stress contours and displacement contours under thermal loads and mechanicalloads, the results show that the equivalent stress is in the range of the material’s yieldstrength and tensile strength.Finally, imported the result of the thermal-mechanical coupling analysis intoDesignLife software, set the S-N curves and related parameters, based on fatigue analysistheory, to calculate the fatigue life of the wobble plate and Z-axis, and the result shows thatboth of them can basically meet the requirements.