肋在塑膠模型中是常見的特徵，在CAE分析上會先將模型轉換成網格，將肋獨立辨識對網格建立有以下兩個優點，(1)肋在設計變更後，只要改變本身網格，無須重建所有模型網格，(2)建立一套專屬肋的自動化網格生成系統。本研究的目的為發展B-rep模型肋特徵辨識及混合式實體網格建構研究。肋特徵根據下列五個步驟獲得辨識結果，並且依照肋的網格生成方式建立資訊，(1)建立邊面屬性，(2)終止面搜尋，利用Rule-based方式搜尋面，(3)殼面計算與搜尋，(4)肋條件判斷，(5)儲存肋資訊。完整的流程將在論文中完整說明，流程中每一步驟也將詳細說明。利用63個CAD模型做為案例測試，其中54個模型之肋可正確辨識，9個模型肋無法辨識，主要有少數原因為原始CAD模型幾何形狀較複雜，詳細辨識結果與討論將在論文中說明。;In CAE analysis, it is required to convert CAD models into solid meshes. Rib is a common feature in plastic parts to improve the strength of a structure. There are two advantages for rib-feature recognition in solid mesh generation: (1) it is usually necessary to perform what if study during the analysis. When a rib feature is recognized, it may become easy to perform such an analysis because the meshes related to this rib can be generated independently; (2) with the rib features available, it may be easy to generate prism and hexahedron meshes for the rib features. The purpose of this study is to develop a feature recognition algorithm for ribs and investigate the data that should be recorded for hybrid mesh generation. The proposed algorithm is divided into the following five steps: (1) create the AAG (attributes adjacency graph); (2) search end faces in accordance with a rule-based method for face searching; (3) Search shell faces; (4) judge the condition of each rib; (5) record rib information. The overall flowchart of the proposed method is described in this thesis. Detailed description of each step in the flowchart is explained also. 63 CAD models are employed to verify the feasibility of the proposed method, in which 54 of them are fully successful, while some of the ribs are misjudged for the remained 9 CAD models. A detailed discussion for all examples is provided, emphasizing on the reasons for misjudged cases.
