在有限元素分析中，實體網格扮演極重要的角色，以目前網格自動搭建
技術而言，四面體網格與邊界層網格最為成熟，但容易在角落產生狹長網格，
導致品質不良，直接影響分析結果與效率，為改善此情況，本實驗室致力發
展六面體網格與三角柱網格的自動搭建。
以射出成型中最常見的薄殼元件為例，殼上坐落多種凸起特徵，包含管、
柱、肋與其它複雜凸起結構，以往這類結構皆由工程師手動搭建而成，過程
重複且無趣，同時花費許多時間，因此，若能將此類凸起物自動辨識，後續
紀錄凸起物之間的關聯性，必能以面配對的方式協助實體網格搭建。
綜上所述，本研究以倒斜角辨識、內外面辨識、外部輔助面辨識為主題，
開發相關演算法，紀錄模型內外面屬性資料，希望在後續辨識過程中，提供
薄殼特徵辨識與薄殼特徵分解相關資料。

Solid meshes play a very important role in finite element analysis. For the
time being, the complete automatic construction technology of tetrahedral meshes
and boundary layer meshes is mature enough. However, it is easy to generate
narrow meshes on the corners, resulting in poor quality. It will directly affect the
analysis results and efficiency. In order to improve this situation, our laboratory
is committed to developing the automatic construction of hexahedral meshes and
prism meshes.
Taking the most common thin shell component in injection molding as an
example, there are various protrusion-features on the shell, including tubes,
columns, ribs and other complex structures. In the past, the meshes of those
structures were built manually by engineers. The process was repetitive and
boring, and it wasted a lot of time. Therefore, if such protrusions can be
recognized automatically and the correlation between the protrusions can be
recorded, it will assist in the construction of solid meshes.
For the reason, this research focuses on chamfer recognition, inner and outer
face recognition, and outer auxiliary face recognition. Develop related algorithms,
hoping to record the results of inner and outer face types data during the
recognition process, so as to provide relevant information for subsequent feature
decomposition and meshes construction.

[1]S. S. Liu, Y. Lu, J. Kraftcheck and R. Gadh, “Feature recognition applications in mesh generation,” Mechanical Engineering Dept. University of Wisconsin-Madison, 1997.
[2]Y. Lu, R. Gadh and T. J. Tautges, “Feature based hex meshing methodology: feature recognition and volume decomposition,” Computer-Aided Design, Vol. 33, pp. 221-232, 2001.
[3]M. Nieser, U. Reitebuch, and K. Polthier, “Cubecover – parameterization of 3D volumes,” Eurographics symposium on geometry processing, Vol. 30, No. 5, Switzerland, Lausanne, 2011.
[4]H. Zhu et al., “Automatic hierarchical mid-surface abstraction of thin-walled model based on rib decomposition,” Advances in Engineering Software, Vol. 97, pp. 60-71, 2016.
[5]L. Sun, C. M. Tierney, C. G. Armstrong and T. T. Robinson, “Automatic decomposition of complex thin walled cad models for hexahedral dominant meshing,” Procedia Engineering, Vol. 163, pp. 225-237, 2016.
[6]L. D. Floriani, S. Ansaldi and B. Falcidieno, “Geometric modeling of solid objects by using a face adjacency graph representation,” ACM SIGGRAPH Computer Graphics, Vol. 19, No. 3, pp. 131-139, 1985.
[7]S. Joshi and T. C. Chang, “Graph-based heuristics for recognition of machined features from a 3D solid model,” Computer-Aided Design, Vol. 20, No.2, pp. 56-58, 1988.
[8]F. Tian, X. Tian, J. Geng, Z. Li and Z. Zhang, “A hybrid interactive feature recognition method based on lightweight model,” 2010 International Conference on Measuring Technology and Mechatronics Automation (ICMTMA), Vol. 1, pp. 113-117, 2010.
[9]Y. G. Li, Y. F. Ding, W. P. Mou and H. Guo, “Feature recognition technology for aircraft structural parts based on a holistic attribute adjacency graph,” Part B: Journal of Engineering Manufacture, Vol. 224, pp. 271-278, 2010.
[10]許惟純，「以 B-rep 為基礎之肋特徵辨識技術發展」，國立中央大學碩士論文，2014年。
[11]游子威，「以B-rep為基礎之混接曲面辨識技術發展」，國立中央大學碩士論文，2014年。
[12]陳星佑，「CAE應用之混接面辨識技術發展」，國立中央大學碩士論文，2014年。
[13]宋培溥，「應用於模流分析之薄殼元件CAD模型特徵辨識與分解技術發展」，國立中央大學碩士論文，2021年。
[14]王培懿，「CAD模型混接面、虛擬環及孔洞特徵辨識技術發展」，國立中央大學碩士論文，2022年。
[15]H. Wibhisana, “Development of chamfer recognition technology for CAD model,” National Central University, 2017.
[16]M. W. Fu, A. Y. C. Nee and J. Y. H. Fuh, “The application of surface visibility and moldability to parting line generation,” Computer Aided Design, Vol. 34, No. 6, pp. 469-480, 2002.
[17]J. Q. Ran and M. W. Fu. “Design of internal pins in injection mold CAD via the automatic recognition of undercut features,” Computer Aided Design, Vol. 42, No. 7, pp.582-597, 2010.
[18]吳闓任，「以 B-rep 為基礎之薄殼元件凸起特徵辨識技術發展」，國立中央大學碩士論文，2017年。
[19]鍾佳穎，「薄殼之 CAD 模型凸起物特徵辨識與分解技術發展」，國立中央大學碩士論文，2018年。
[20]蕭安勝，「塑膠射出薄殼件之CAD模型凸起面特徵辨識與分模應用技術發展」，國立中央大學碩士論文，2019年。
[21]P. Putrayudanto, “Face types recognition for thin-shell cad models,” National Central University, 2021.
[22]Rhino, Website：http://www.rhino3d.com/, Accessed 22 June 2022.
[23]OpenNURBS, Website：http://www.rhino3d.com/tw/opennurbs/, Accessed 22 June 2022.
[24]張倢綜，「CAD 模型基礎擠出物之實體網格自動化建構技術發展」，國立中央大學碩士論文，2018年。
[25]Moldex3D, Website：http://www.moldex3d.com/en/, Accessed 22 June 2022.
[26]CADdoctor, Website：http://elysiuminc.com/products/caddoctor/, Accessed 22 June 2022.