外文翻譯----三維注射成型流動模擬的研究-其他專業(yè)-wenkub
2023-01-30 09:08:34 本頁面
【正文】 y finite difference method， is neglected． With the development of molding techniques， molded 華東交通大學(xué)理工學(xué)院畢業(yè)設(shè)計（論文） 53 parts will have more and more plex geometry and the difference in the thickness will be more and more notable， so the change in the gapwise (thickness) dimension of the physical quantities can not be neglected． In addition， the flow simulated looks unrealistic in as much as the melt polymer flows only on surfaces of cavity, which appears more obvious when the flow simulation is displayed in a mould cavity． 3D simulation model has been a research direction and hot spot in the scope of simulation for plastic injection molding． In 3D simulation model， velocity in the gapwise (thickness) dimension is not neglected and the pressure varies in the direction of part thickness， and 3 D finite elements are used to discretize the part geometry． After calculating， plete data are obtained(not only surface data but also internal data are obtained)． Therefore, a 3D simulation model should be able to generate plementary and more detailed information related to the flow characteristics and stress distributions in thin molded parts than the one obtained when using a model(based on the HeleShaw approximation)． On the other hand， a 3D model will predict more accurately the characteristics of molded parts having thick walled sections such as encountered in gas assisted injection molding． Several flow behaviors at the flow front． such as “fountain flow”． which model cannot predict, can be predicted by 3D mode1. Meanwhile, the flow simulation looks more realistic inasmuch as the overall an analysis result is directly displayed in 3D part geometry or transparent mould cavity． This Paper presents a 3 D finite element model to deal with the three—dimensional flow, which employs an equa1order velocitypressure formulation method [3,4]． The relation between velocity and pressure is obtained from the discretized momentum equations, then substituted into the continuity equation to derive pressure equation． A 3D control volume scheme is employed to track the flow front． The validity of the model has been tested through the analysis of the flow in cavity． 2 Governing Equations The pressure of melt is not very big during filling the cavity, in addition， reasonable mold structure can avoid over big pressure， so the melt is considered inpressible． Inertia and gravitation are neglected as pared to the viscous force． With the above approximation， the governing equations， expressed in cartesian coordinates，are as following： 54 Momentum equations Continuity equation Energy equation where, x， y， z are three dimensional coordinates and u, v， w are the velocity ponent in the x, y, z directions． P， T， ρandη denote pressure， temperature, density and viscosty respectively． Cross viscosity model has been used for the simulations： where， n
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