薄殼CAD模型之薄殼本體體積分解技術發展

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题名:	薄殼CAD模型之薄殼本體體積分解技術發展
作者:	周子耀;Chou, Tzu-Yao
贡献者:	機械工程學系
关键词:	體積分解
日期:	2021-08-03
上传时间:	2021-12-07 13:26:29 (UTC+8)
出版者:	國立中央大學
摘要:	在射出成型產業中，薄殼元件是一種很常見的零組件，設計產品時會以模流分析來輔助，以降低設計成本。在模流分析前，需要為CAD模型建構實體網格，以提供求解器進行計算，其中實體網格的數量、結構及品質，將決定求解器的效率與準確性。一般而言，因為四面體網格可以自動建構，所以使用者會為薄殼元件建構四面體網格，但是此類型網格的品質不佳，造成計算結果與實際情況有所誤差，因此需改成建構三角柱網格或六面體網格，來提升計算的準確性。但是這兩類網格的建構方式，通常以手動方式建構。本研究的目的為發展針對薄殼元件之薄殼本體體積分解的演算法，以輔助建構三角柱網格與六面體網格。在本研究中，會先使用本實驗室開發之特徵辨識技術，將薄殼本體與特徵分離後，根據建構結構式網格的概念，把薄殼本體分解成數種區塊，包括主要區塊、特徵區塊、與剩餘區塊，其中區塊記錄多個與原始模型相對應的封閉輪廓，本研究之主要工作為各類型區塊封閉輪廓計算演算法之發展，所建立之區塊緊密相連，無任何間隙，精確描述薄殼本體之體積。;In injection molding, thin-shell parts exist commonly. Mold flow analysis is extensively used in injection molding to assist the product and mold design, as well as the process analysis. In mold flow analysis, it is necessary to generate solid meshes for a CAD model so that the solver can perform the required analysis. The quantity, structure and quality of solid meshes can affect the efficiency and accuracy of the simulation. Generally, tetrahedral meshes are extensively used as it is easy to be generated automatically. However, the quality of this type of mesh is worse and it tends to result in inaccurate simulation result. Prismatic and hexahedral meshes are an alternative for improving the simulation result. These two types of meshes, however, are often generated manually. The purpose of this study is to develop an algorithm for decomposing the volume of the thin shell of a thin-shell CAD model, which can assist the generation of better type of meshes for the model. The proposed method will employ the feature recognition technology developed in our laboratory to separate protrusions from the thin shell, and then divide the remaining thin shell into several types of regions, including main regions, feature regions and residual regions. Each region is essentially described by a set of closed contours. The primary work of this study to develop algorithms to compute the edges and contours for all types of regions. All regions established are tightly neighboring to each other, without any gap in between, and hence accurately describe the volume of the thin shell.
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