| The piston as a core component of operation in the engine, because of its high strength by the thermal load and mechanical load cycling action, more prone to erosion or rupture pin seat. And with the internal combustion engine to enhance the performance of its components are increasingly high requirements, Especially the pressure increases caused by mechanical stress increases, causing the deadly impact of the fatigue life of the piston, therefore, anti-fatigue optimized piston design for more and more attention has been paid. In this paper, the current design optimization with regard to weight-optimized piston constraints unsound, using Ncode handle multiple software design verification on fatigue life can’t be introduced into the initial design constraints this situation, proposing based on Approximation model fatigue verification piston weight weight optimization. By design fatigue life will be calculated as constraints to improve the design of the traditional design of useless fatigue life due to ill-considered, to improve the accuracy of the optimization of efficiency and results. In this paper, the research work done as follows:(1) Firstly, the original model for packet processing piston, the piston is broken down into several different parts of the body, step by step into Finite element software for meshing; Parametric complete separation of the working piston area to be optimized by Finite element software in Boolean operations for the following calculation provides a space-optimized data.(2) Select the third boundary condition at the piston temperature field calculation by calculating the heat transfer coefficient and the completion of the boundary conditions in software is applied and the temperature field calculations, the steady-state temperature field contours of the piston; Then they subjected to analysis and calculation of mechanical stress according to the motion of the piston, by coupling the temperature field calculation result, equivalent force of the piston heat engine coupled static and transient thermo-mechanical coupling, the deformation cloud, while extracting the transient calculation APDL commands and results as an input file for fatigue analysis for analysis.(3) According to the fatigue life calculation features, choose mature Miner linear cumulative damage theory as criteria, while the piston according to high-cycle fatigue characteristics, choose the nominal stress method for calculating the standard piston fatigue life, through rain flow counting method to complete the piston load spectrum screening, according to the last piston material S-N curve, calculated evaluation consumption coefficient piston fatigue life.(4) Finally, according to research content and research model, establishing by the Latin Hypercube method optimization test the 30 sets of data, and fitting approximation model based on the calculation result corresponding to each set of data, after the accuracy of the model was verified by calling the approximate model complete piston fatigue optimization process.Through the above analysis, obtained under the minimum weight of the piston corresponding to the design space, in order to further verify the accuracy of the results, import software, temperature field, analyze static heat engine coupled transient thermal-mechanical coupling and contrast before and after optimization the cloud determine its compliance with the requirements of the material of the piston, Finally, according to Ncode software, complete validation fatigue life of the piston body. |
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