高效健壮的直接建模算法研究

发布时间：2018-06-19 20:16

本文选题：鲁棒性 + 直接建模　；参考：《浙江大学》2017年硕士论文

【摘要】：参数化特征建模是目前主流的CAD建模方法,但是随着现在的模型越来越复杂,对参数化特征模型进行变动修改的效率和健壮性变得越来越低,而且基于历史的建模方式限制了用户在进行模型变动修改时的灵活性。与参数化特征建模不同,直接建模可以对点、边、面直接进行操作,其建模过程与历史无关,特别是直接建模在进行复杂模型变动修改时具有高效、灵活的特点,因此直接建模技术越来越受到重视。鉴于目前的直接建模技术还存在不足之处,本文针对现有方法所存在的问题,研究健壮高效的直接建模算法。本文主要开展的工作包括:(1)提出基于B-rep直接修改的直接建模算法。该算法通过对B-rep直接进行简单的几何拓扑修改操作而不采用复杂耗时的布尔运算实现直接建模功能,不仅比现有方法更加鲁棒,而且更加高效。(2)提出基于拓扑图的过渡特征组生成/抑制顺序确定算法。该算法通过充分利用过渡面之间的拓扑上下文,得到更加合理的过渡特征生成/抑制顺序。(3)提出能够有效处理自由曲面的直接建模算法。该算法通过合理拓展自由曲面以及有效构建延展自由曲面和目标操作自由曲面,使得算法能够处理带有自由曲面的复杂模型。最后,在本文工作的基础上,设计并实现一个直接建模原型系统,通过实例测试验证了本文所提出算法的有效性。
[Abstract]:Parameterized feature modeling is the mainstream CAD modeling method at present, but with the increasing complexity of the present model, the efficiency and robustness of modifying the parameterized feature model become lower and lower. Moreover, the historical modeling method limits the flexibility of the user when making model changes. Different from parameterized feature modeling, direct modeling can operate directly on points, edges and surfaces, and its modeling process has nothing to do with history. Especially, direct modeling has the characteristics of high efficiency and flexibility in changing and modifying complex models. Therefore, more and more attention has been paid to direct modeling technology. In view of the shortcomings of the current direct modeling techniques, this paper studies a robust and efficient direct modeling algorithm in view of the problems existing in the existing methods. The main work of this paper is to propose a direct modeling algorithm based on B-rep. This algorithm implements the direct modeling function by directly modifying B-rep geometry and topology without using complex and time-consuming Boolean operations, which is not only more robust than the existing methods. Furthermore, a new transition feature group generation / suppression order determination algorithm based on topology graph is proposed. By making full use of the topological context between the transition surfaces, the algorithm obtains a more reasonable transition feature generation / suppression order. 3) A direct modeling algorithm which can effectively deal with free surface is proposed. By extending the free surface reasonably and effectively constructing the extended free surface and the target operating free surface, the algorithm can deal with the complex model with the free surface. Finally, a direct modeling prototype system is designed and implemented on the basis of the work in this paper. The effectiveness of the proposed algorithm is verified by an example.
【学位授予单位】：浙江大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TP391.7

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