CAD模型混接面、虛擬環及孔洞特徵辨識技術發展

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研究生：	王培懿 Pei-Yi Wang
論文名稱：	CAD模型混接面、虛擬環及孔洞特徵辨識技術發展
指導教授：	賴景義 Jiing-Yih Lai
口試委員:
學位類別：	碩士 Master
系所名稱：	工學院 - 機械工程學系 Department of Mechanical Engineering
論文出版年：	2022
畢業學年度：	110
語文別：	中文
論文頁數：	183
中文關鍵詞：	混接面、虛擬環、孔洞
外文關鍵詞：	Blend face, Virtual loop, Hole
相關次數：	點閱：23 下載：0
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隨著技術的發展與模型元件的複雜度日益提升，模流分析(Mold flow analysis)已普遍用於射出成形產業，利用CAD模型轉換成實體網格，讓模流分析的求解器進行分析。以不同搭建方式的實體網格，會影響到求解器分析的最終結果。其中，四面體網格雖然適用於各種形狀的模型，並能自動搭建而成，但生成的網格數量與展旋比等數據相較於六面體網格等結構化網格而言，數量有倍數上的差異與不均勻的展弦比等不良因素，致使分析結果不佳。因此結構化網格更適用於模流分析，但結構化網格需要較為規則化的區塊方能建立，使得搭建方式顯得複雜且繁瑣。本研究主要目的為開發CAD模型上的特徵辨識演算法，用於後續的特徵分解以輔助結構化網格的搭建。本研究於特徵辨識中主要著重於混接面(Blend face)、虛擬環(Virtual loop)與孔洞特徵發展自動化特徵辨識技術，並改善過去演算法中無法辨識、錯誤分類與過度辨識等問題。接著，藉由測試更多種類的模型，將辨識技術繼續向下發展，使演算法能精確判斷更多元案例的特徵，最後提供完整的辨識資料給與後續相關的程序使用。

With the development of technology and the increasing complexity of model components, mold flow analysis (Mold flow analysis) has been widely used in the injection molding industry. The CAD model is converted into a solid mesh for analysis by the mold flow analysis solver. Solid meshes constructed in different ways will affect the final result of the solver analysis. Among them, although the tetrahedral mesh is suitable for models of various shapes and can be built automatically, the data such as the number of meshes and aspect ratios generated are more expensive than those of structured meshes such as hexahedral meshes. There are unfavorable factors such as difference in multiples and uneven aspect ratio, resulting in poor analysis results. Therefore, structured meshes are more suitable for mold flow analysis, but they require relatively regular blocks to be established, which makes the construction method complex and cumbersome. The main purpose of this research is to develop a feature recognition algorithm on CAD models for subsequent feature decomposition to assist in the construction of structured meshes. In feature recognition, this research mainly focuses on the development of automatic feature recogntion technology for blend faces, virtual loops and hole features.With the purposes of improving the problems of non-recognizd, misclassified and over-recognized in the past algorithms. Then, by testing more types of models, the identification technology will continue to develop downward, so that the algorithm can accurately determine the features of more multi-cases, and finally provide complete recognition data for subsequent related programs.

摘要    i
Abstract    ii
致謝    iii
目錄    iv
圖目綠    vii
第一章    緒論    1
1    前言    1
2    文獻回顧    3
2.1    特徵辨識前置資料計算相關文獻    3
2.2    特徵辨識相關文獻    6
3    研究目的    6
4    研究方法    8
4.1    CAD模型前處理    8
4.2    特徵辨識    8
5    論文架構    10
第二章    混接面辨識方法修正    12
1    前言    12
2    混接面分類    12
3    混接面演算法簡介    14
3.1    混接面計算相關名詞說明    14
3.2    演算法流程介紹    18
4    演算法辨識錯誤說明    24
5    演算法辨識錯誤修正    29
5.1    邊及面拓樸資料計算修正    29
5.2    混接面初步辨識修正    32
5.3    混接面分類計算修正    36
6    混接面辨識結果分析    45
第三章    虛擬環辨識程式發展    48
1    前言    48
2    虛擬環分類    48
3    虛擬環辨識整體流程說明    50
3.1    虛擬環計算相關名詞說明    50
3.2    演算法整體流程    52
4    虛擬環辨識演算法    56
4.1    計算平滑面分群    56
4.2    計算倒角面分群    57
4.3    辨識Single loops    60
4.4    辨識Virtual loops    60
4.5    合併計算相鄰的面群    66
4.6    辨識Multi-virtual loops    71
4.7    辨識Gap loops    75
5    虛擬環辨識結果分析    80
第四章    孔洞辨識程式發展    85
1    前言    85
2    孔洞的總類與組成面說明    85
3    孔洞演算法整體說明    87
4    孔洞辨識演算法    90
4.1    使用Loop資料計算孔洞    90
4.2    使用面資料計算孔洞    96
4.3    判斷孔洞的基本類型    102
4.4    計算孔洞的相鄰關係    105
4.5    計算階梯孔與複雜孔結構    105
5    孔洞辨識結果說明    107
第五章    案例辨識結果分析與討論    111
1    前言    111
2    混接面辨識結果分析    111
2.1    案例測試與比較    111
2.2    問題討論    127
3    虛擬環辨識結果分析    129
3.1    案例測試與比較    129
3.2    問題討論    140
4    孔洞辨識結果分析    142
4.1    案例測試與比較    142
4.2    問題討論    154
第六章    結論與未來展望    158
1    結論    158
2    未來展望    160
參考文獻    162

                                

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