摘要(英) |
A thin-shell CAD model can typically be divided into inner and outer regions, on which various structural and functional features are resided. The recognition of various types of faces on a thin-shell CAD model is an essential step in feature recognition that can be used for automatic generation of better type of meshes. The essence of this paper is to propose a method for detaching face types, including inner, auxiliary and outer faces, on thin-shell parts. Firstly, a thin-shell part is split into two types of regions: observable and unobservable, based on the mold opening direction, called inner and outer faces, respectively. Secondly in auxiliary faces recognition, the inner faces are then divided into several types, including: transition, wall, next-layer wall, base, ridge and inner protrusion faces, where the first five types are termed auxiliary faces. Finally, in outer faces recognition, the outer faces are divided into the following face types: flange, shell, ground and outer protrusion faces. Also, the thin-shell CAD models are divided into two types: concave-shell and non-concave shell cases, for facilitating the development of outer-faces recognition algorithm. A detailed description of the algorithms for inner-and-outer faces splitting, auxiliary faces recognition, and outer faces recognition is provided in this thesis. Also, realistic thin-shell CAD models are tested to demonstrate the feasibility of the proposed method. With these types of faces recognized, appropriate meshing algorithms that can yield a better type of solid meshes could be developed for the meshing of thin-shell CAD models. |
參考文獻 |
[1] L. D. Floriani, S. Ansaldi and B. Falcidieno, “Geometric Modeling of Solid Objects by Using a Face Adjacency Graph Representation,” ACM SIGGPAPH Computer Graphs, Vol. 19, No. 3, pp. 131-139, 1985.
[2] S. Joshi and T. C. Chang, “Geometric Reasoning for Recognition of Machined Features from a 3D Solid Model,” Computer-Aided Design, Vol. 20, No. 2, pp. 58-66, 1988.
[3] 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.
[4] 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.
[5] C. J. Zhang, X. H. Zhou and C. X. Li, “Automatic Recognition of Intersecting Features of Freeform Sheet Metal Parts,” J. Zhejiang Univ. Sci. A., Vol. 10, pp. 439-1449, 2009.
[6] T. Wong, S. T. Tan and W. S. Sze, “Parting Line Formation by Slicing a 3D CAD Model,” Engineering with Computers, Vol. 14, pp. 330-343, 1998.
[7] Y. Lu, R. Gadh and T. Tautges, “Volume Decomposition and Feature Recognition for Hexahedral Mesh Generation,” Proceedings of the 8th International Meshing Roundtable, 1999.
[8] T. Lim, H. Medellin, C. Torres-Sanchez, J. R. Corney, J. M. Ritchie and J. B. C. Davies, "Edge-based Identification of DP-features on Free-form Solids," IEEE Transactions on Pattern Analysis and Machine Intelligence, Vol. 27, No. 6, pp. 851-860, 2005.
[9] M. Marefat and R. L. Kashyap, "Geometric Reasoning for Recognition of Three-dimensional Object Features," IEEE Transactions on Pattern Analysis and Machine Intelligence, Vol. 12, No. 10, pp. 949-965, 1990.
[10] A. Y. C. Nee, M. W. Fu, J. Y. H. Fuh, K. S. Lee and Y. F. Zhang, “Determination of Optimal Parting Directions in Plastic Injection Mold Design,” CIRP Annals, Vol. 46, No. 1, pp. 429-432, 1997.
[11] M. C. Fields and D. C. Anderson, “Fast Feature Extraction for Machining Applications,” Computer-Aided Design, Vol. 26, No. 11, pp. 803-813, 1994.
[12] H.L. Lockett and M. D. Guenov, "Graph-based Feature Recognition for Injection Moulding Based on a Mid-surface Approach," Computer-Aided Design, Vol. 37, No. 2, pp. 251-262, 2005.
[13] P. P. Song, J. Y. Lai, Y. C. Tsai and C. H. Hsu, “Automatic Recognition and Suppression of Holes on Mold Bases for Finite Element Applications,” Engineering with Computers, Vol. 35, No. 3, pp. 925–944, 2019.
[14] J. Y. Lai, M. H. Wang, P. P. Song, C. H. Hsu and Y. C. Tsai, “Automatic Recognition and Decomposition of Rib Features in Thin-shell Parts for Mold Flow Analysis,” Engineering with Computers, Vol. 34, No. 4, pp. 801–820, 2017.
[15] 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
[16] Rhinoceros CAD, available from https://www.rhino3d.com/, accessed on 31-Dec-2020.
[17] openNURBS, available from: https://www.rhino3d.com/opennurbs/, accessed on 31-Dec-2020. |