面向注塑模CAE的特征造型、变密度网格划分及中面抽取
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摘要
针对注塑模CAE技术实用化中急需解决的关键问题，重点研究了注塑模中面模型的特征造型、中面模型的自适应变密度网格生成及实体模型向中面模型的自动转化技术，并将其集成到注塑模CAE软件，初步实现CAD／CAE／CAM软件的无缝拼接，使CAE软件更方便、更快捷，为实现CAE技术的集成化和智能化奠定必要的基础。主要工作包括：
(1)通过形体的特征分类及其相互之间的联系，给出了基于特征的注塑模中面模型造型方法。此模型集成了中面模型的造型信息、网格划分信息和数值模拟计算有关的几何信息，从而实现了中面模型造型和有限元网格划分一体化，使得中面模型的造型、网格划分及其修改更加方便、快捷。
(2)对于任意平面区域，基于推进波前法，通过引入新的网格尺寸动态控制方法，提出了高质量变密度三角形网格的生成方法。本算法生成的三角形质量高，并且能保证不同尺寸三角形的光滑过渡。对于平面区域，只要给定点、线或者某个区域的网格划分尺寸，系统会自适应生成疏密光滑过渡的变密度网格。
(3)对于曲面区域，给出了利用参数域生成均匀网格和变密度三角形网格的方法。从网格划分实例来看，本算法生成的三角形质量好，计算效率高，且算法简单有效，适合大部分曲面的三角形网格划分，从而可满足一般情况下有限元计算的需要。
(4)基于商用CAD软件生成的用STL文件表示的薄壁注塑件实体模型，给出了表面有限元网格模型的生成方法。该方法生成了质量较高的表面三角形网格，一方面可直接用于双面流动分析，另一方面，在此基础上抽取中面网格模型用于中面流动模拟分析。
(5)基于实体的表面网格模型，提出了中面模型的抽取方法，生成中面网格模型供注塑模流动模拟分析用。采用该技术可以直接利用CAD生成的实体模型进行中面流动分析，初步实现了商用CAD软件和注塑模CAE软件的无缝拼接。
(6)针对基于中面模型的注射模CAE模拟分析结果，给出了利用彩色等值线图、彩色云图以及计算机动画显示网格模型及计算结果数据场的可视化方法，对于更好地理解和处理注射成型数值模拟计算产生的大量数据，分析成型过程中各种物理量的分布特征提供了一个形象直观的方法。
In order to solve some key problems for using plastics injection mold CAE techniques, the research of feature-based modeling, graded meshing, and mid-plane model extraction are studied in this dissertation. These work have been programmed and integrated into a plastics injection mold CAE software, which makes the using of CAE software convenient and fast. The main results is following:
(1) A method of feature-based mid-plane modeling is proposed by means of feature classification. This model includes the information about geometric modeling, meshing, and simulation, which put mid-plane model and FEM meshing into a body. It makes mid-plane modeling, meshing, and correction to the model more convenient and faster.
(2) The Advancing Front Method is adopted to generate graded mesh on arbitrary plane using a new mesh size dynamically controlling method. The result triangles have higher quality and smooth transition to different sizes. If the mesh size at one point, one line segment, or one region is defined, the program will generate automatically. A triangulation is finished on a parametric field for a curved region, and a graded mesh can be generated for some ordinary ones.
(3) A methods for generating uniform mesh and graded mesh is proposed on a parametric field for some curved regions. This method is efficient and the resultant triangles have good quality. Because the methods are suite for many curved regions, it can meet the requirement of FEM computation in ordinary occasions.
(4) Based on a STL file of thin-wall part, which can be produced by almost each commercial CAD software, an algorithm is proposed for Mid-plane mesh model extraction. By this technique, a higher qualitative surface triangle mesh suited for FEM is attained after re-meshing. Not only the mesh can be used to two-domain flowing analysis, but also used to extract the mid-plane model for the mid-plane flowing simulation.
(5) Based the surface mesh of a solid, a mid-plane model is extracted which is suited for plastic injection simulation. By this technique a solid model out of CAD software is directly used to flow analysis ,which makes it possible to integrate CAE with CAD.
(6) A visualization method is proposed to display the mesh model and the simulation resultant data fields of plastics injection mold CAE, which include color
isograms, color nephogram and computer cartoon. These provide some valid tools to better understanding a great deal of data which comes from FEM computation.
(1)通过形体的特征分类及其相互之间的联系，给出了基于特征的注塑模中面模型造型方法。此模型集成了中面模型的造型信息、网格划分信息和数值模拟计算有关的几何信息，从而实现了中面模型造型和有限元网格划分一体化，使得中面模型的造型、网格划分及其修改更加方便、快捷。
(2)对于任意平面区域，基于推进波前法，通过引入新的网格尺寸动态控制方法，提出了高质量变密度三角形网格的生成方法。本算法生成的三角形质量高，并且能保证不同尺寸三角形的光滑过渡。对于平面区域，只要给定点、线或者某个区域的网格划分尺寸，系统会自适应生成疏密光滑过渡的变密度网格。
(3)对于曲面区域，给出了利用参数域生成均匀网格和变密度三角形网格的方法。从网格划分实例来看，本算法生成的三角形质量好，计算效率高，且算法简单有效，适合大部分曲面的三角形网格划分，从而可满足一般情况下有限元计算的需要。
(4)基于商用CAD软件生成的用STL文件表示的薄壁注塑件实体模型，给出了表面有限元网格模型的生成方法。该方法生成了质量较高的表面三角形网格，一方面可直接用于双面流动分析，另一方面，在此基础上抽取中面网格模型用于中面流动模拟分析。
(5)基于实体的表面网格模型，提出了中面模型的抽取方法，生成中面网格模型供注塑模流动模拟分析用。采用该技术可以直接利用CAD生成的实体模型进行中面流动分析，初步实现了商用CAD软件和注塑模CAE软件的无缝拼接。
(6)针对基于中面模型的注射模CAE模拟分析结果，给出了利用彩色等值线图、彩色云图以及计算机动画显示网格模型及计算结果数据场的可视化方法，对于更好地理解和处理注射成型数值模拟计算产生的大量数据，分析成型过程中各种物理量的分布特征提供了一个形象直观的方法。
In order to solve some key problems for using plastics injection mold CAE techniques, the research of feature-based modeling, graded meshing, and mid-plane model extraction are studied in this dissertation. These work have been programmed and integrated into a plastics injection mold CAE software, which makes the using of CAE software convenient and fast. The main results is following:
(1) A method of feature-based mid-plane modeling is proposed by means of feature classification. This model includes the information about geometric modeling, meshing, and simulation, which put mid-plane model and FEM meshing into a body. It makes mid-plane modeling, meshing, and correction to the model more convenient and faster.
(2) The Advancing Front Method is adopted to generate graded mesh on arbitrary plane using a new mesh size dynamically controlling method. The result triangles have higher quality and smooth transition to different sizes. If the mesh size at one point, one line segment, or one region is defined, the program will generate automatically. A triangulation is finished on a parametric field for a curved region, and a graded mesh can be generated for some ordinary ones.
(3) A methods for generating uniform mesh and graded mesh is proposed on a parametric field for some curved regions. This method is efficient and the resultant triangles have good quality. Because the methods are suite for many curved regions, it can meet the requirement of FEM computation in ordinary occasions.
(4) Based on a STL file of thin-wall part, which can be produced by almost each commercial CAD software, an algorithm is proposed for Mid-plane mesh model extraction. By this technique, a higher qualitative surface triangle mesh suited for FEM is attained after re-meshing. Not only the mesh can be used to two-domain flowing analysis, but also used to extract the mid-plane model for the mid-plane flowing simulation.
(5) Based the surface mesh of a solid, a mid-plane model is extracted which is suited for plastic injection simulation. By this technique a solid model out of CAD software is directly used to flow analysis ,which makes it possible to integrate CAE with CAD.
(6) A visualization method is proposed to display the mesh model and the simulation resultant data fields of plastics injection mold CAE, which include color
isograms, color nephogram and computer cartoon. These provide some valid tools to better understanding a great deal of data which comes from FEM computation.
引文
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