【作者】 崔秀芬；

【导师】 高曙明；

【作者基本信息】 浙江大学 ， 计算机应用， 2004， 硕士

【摘要】 近几年来，由于CAD／CAE／CAM无缝集成的迫切要求，CAD模型简化技术正越来越成为CAD领域的研究热点。过渡特征识别与抑制是简化CAD模型技术的一个重要部分，是有效实现CAD／CAE／CAM集成必不可少的一步。本文在分析与总结前人所做工作的基础上，对过渡特征识别与抑制问题进行了比较深入的研究，提出了一种高效的过渡特征识别与抑制算法。该算法首先识别出零件中所有的过渡特征，然后基于整体思想将它们依次从零件中抑制掉，从而达到简化CAD模型的目的。 全文的组织结构如下： 第一章首先综述CAD模型简化技术的主要研究内容、应用领域和发展现状，并对现有CAD模型简化技术中存在的问题进行了提炼和分析；然后介绍自由形状特征的表示、分类及识别方法，重点对自由形状特征技术的发展现状进行综述；接着介绍过渡特征识别与抑制的主要研究内容、发展现状及存在的问题；最后给出本文的主要研究内容和研究目标。 第二章提出了一种过渡特征识别的新方法。首先引入与过渡特征及本章算法相关的一些概念；然后详细介绍如何从零件实体模型中识别出所有的过渡面，并将其分为边过渡面和点过渡面两类；最后具体介绍过渡特征识别算法。本章的一个重点是过渡特征识别算法中混合过渡区域的处理，介绍零件中边缘过渡面和叠加过渡面的处理方法。 第三章提出了一种基于整体思想的过渡特征抑制方法，该方法将各过渡特征中包含的所有过渡面作为整体一次性抑制。首先介绍在过渡特征抑制过程中用到的几个拓扑修改操作和几何修改操作，它们分别用来修改CAD模型的拓扑信息和几何信息，这些操作保证了抑制后所得新零件在拓扑上和几何上都有效；然后详细叙述基于整体的过渡特征抑制算法；再介绍退化过渡面的处理方法；最后给出实验结果。 第四章提出一种与其他特征发生相交的过渡面即相交过渡面的识别与抑制方浙江大学硕士学位论文法。首先给出相交过渡面的定义和相关工作分析;然后介绍利用过渡面上的尖边信息来检测相交过渡面的相交过渡面识别算法:再给出相交过渡面的抑制算法;最后给出实验结果。 第五章介绍一个具有过渡特征识别和抑制功能的自动加工特征识别系统一ZD一AFRS系统，其中过渡特征识别与抑制可以作为对零件进行加工特征识别的预处理模块，也可以独立运行，得到过渡特征被抑制后的简化零件。这一章阐述了ZD_AFRS系统的系统结构、过渡特征识别与抑制功能模块实现中的部分核心数据结构及其关键实现方法，最后通过图例介绍过渡特征识别与抑制的具体操作过程。 作者在第六章对全文进行了总结，阐明了本文所提过渡特征识别与抑制算法的特点，指出了该算法尚存在的不足与问题，并对今后的研究工作进行了展望。更多还原

【Abstract】 In the recent years, the CAD model simplification technology has been paid more and more attentions for the requirement of seamless integration of CAD/CAE/CAM. Blend feature recognition and suppression is one important portion of CAD model simplification technology, and is an indispensable step to achieve the seamless integration of CAD/CAE/CAM.In this thesis, new approach to recognize and suppress blend features is proposed. The thesis is organized as follows:Chapter 1 first introduces the main research contents, application areas and current status of the research on CAD model simplification technology and points out main problems in the current CAD model simplification technology research; then presents the specification, taxonomy and recognition methods of freeform features, stressing on the current status of freeform feature research; furthermore, discusses the main research contents, current status and main problems of blend feature recognition and suppression. The chapter ends with the primary research contents and objectives of the thesis.Chapter 2 presents a new method of recognizing blend features. The chapter first introduces the basic concepts related to blend features and the proposed algorithm; then presents in detail the method of recognizing all of blend faces from Boundary Representation of a part, which are further organized as edge-blend feature, vertex-blend feature; lastly depicts the recognition algorithm of blend features.Chapter 3 presents a novel blend feature suppression method that suppresses each recognized blend feature as a whole. The chapter first introduces several topological modification operations and geometric modification operations, which are used respectively to modify the topology and geometry information of the model and canensure the validity of the suppressed model; then presents the algorithm of suppressing the blend feature; furthermore, discusses the method of dealing with degenerate blend face; and ends with some test results at last.Chapter 4 presents an algorithm for recognizing and suppressing the interacting blend face. This chapter first presents the concept of interacting blend face and the related work; then introduces the algorithm of recognizing the interacting blend face using the sharp edges on it; furthermore, gives the suppression algorithm of interacting blend face; and ends with some test results.Chapter 5 introduces the hybrid feature recognition system ZD_AFRS with blend feature recognition and suppression facility. Blend feature recognition and suppression can be used as the preprocessing module of machining feature recognition, and can also run independently to simplify the CAD model. In this chapter, ACIS 3D Toolkit, a commercial geometric modeling engine, is briefly introduced first; then the architecture, key data structure and implementation method of the module of blend feature recognition and suppression are described; finally, some examples of recognizing and suppressing blend features using ZD_AFRS are shown.The final chapter summarizes the main results and makes conclusions of the thesis. Some future research work is also described.更多还原