Based On The Temperature Field Test Research On Fatigue Life Prediction Of Aluminum Alloy Piston

Piston is one of key part of engines, work by the periodic change of the gas pressure,reciprocating inertia force, lateral pressure, the pin seat supporting reaction force and frictionforce and mechanical loads; at the same time at the top of the piston with a high temperaturedistribution is not uniform, there is great thermal stress.In the mechanical load and thermalload effects of thermal-mechanical coupling stress, easy to produce fatigue failure.In view ofthe above problems, this paper takes ML142 piston aluminum alloy as the research object,using the finite element software ANSYS simulation analysis of two kinds of maximumcombustion pressure of piston temperature field and coupled thermo-mechanical stress basedfatigue analysis theory, the use of fatigue analysis software MSC.Fatigue to predict two kindsof maximum combustion pressure piston fatigue life.Application of performance analysis software AVL boost simulation in cylinder withcrank angle variation of the gas temperature and the heat transfer coefficient of variation, andobtain the average heat transfer coefficient and the average gas temperature; adopting theexperience formula calculated piston and coolant, inner cooling oil cavity between the heattransfer coefficient, obtained the piston thermal boundary conditions.Using Pro / ENGINEERsoftware to build the 3D solid model into finite element software, ANSYS, on the pistonmodel finite element discretization in finite element models, application of thermal boundarycondition, obtained two of maximum combustion pressure of piston temperature field.At thesame time with the thermocouple method and test a maximum combustion pressure of pistontemperature field for comparative analysis, in order to verify the finite element numericalsimulation of temperature field of the accurate degree. Using FEM software ANSYS, the thermal and structural units having the same numberof nodes under the premise, the setting piston engine coupled to the boundary conditions ofdisplacement and contact boundary conditions, using the sequential coupling method of pistontemperature and mechanical loads are loaded into the piston model, for solving two kinds ofmaximum combustion pressure piston coupled thermo-mechanical stress, analysis the positionof the maximum stress and the risk structure.Thermo mechanical coupling stress of piston into the fatigue analysis softwareMSC.Fatigue, preparation of piston in all load spectrum, fitting under different conditions oftemperature curve setting piston materials, material yield strength and Young’s modulus,select piston equivalent stress for Von Mises stress, the piston in a two maximum combustionpressure fatigue life prediction results.