基于网格数据的CAD到CAE无损映射

【作者】 李晨涛；

【导师】 石明全；

【作者基本信息】 电子科技大学 ， 机械设计及理论， 2011， 硕士

【摘要】 基于特征的实体建模技术的CAD系统主要进行产品的结构设计,CAE系统则用来进行产品的结构力学性能分析,CAD与CAE系统的高度集成能够更高效地完成产品的设计过程。现有的CAD、CAE系统往往采用不同造型引擎和系统精度,因此不存在既能用于设计又能用于分析的统一模型。以几何模型为桥梁实现不同系统之间模型转换的方法往往出现数据的丢失与冗余。鉴于几何模型实现模型转换的种种弊端,本文采用网格模型代替几何模型实现从CAD到CAE系统的无损数据映射。针对CAD系统生成的网格质量不高的问题,本文提出了一种新的四面体网格优化方法。在网格优化过程中需要保留边界网格包含的特征信息,因此研究网格模型特征信息的提取显得非常必要。本文的研究内容主要体现为:1.回顾了CAD/CAE集成的国内外研究现状,分析了各种方法的优点与不足,提出了本文的研究内容和结构安排。2.深入分析了采用几何模型实现模型转换的失败原因,介绍了基于网格模型的CAD到CAE的无损映射的基本原理、基本算法;以CAD平台UG NX5为例介绍了其单元和节点信息的提取方法;分析了常用CAE系统的网格信息的基本格式,并成功实现从UG到ANSYS、Abaqus等大型CAE系统的数据映射。3.使用几何单元转换原理对四面体网格进行优化,介绍了四面体单元质量的度量准则,详细描述了单元转换原理的并行算法和顺序算法,并用单位球模型、胯关节模型进行验证。对同一模型使用不同的四面体网格优化算法进行优化,通过结果对比分析各种方法的优缺点。4.介绍了微分几何的基本理论,通过分析常用方法不足,提出脊线提取的改进算法,包括脐区检测、脐点检测、脊点检测以及脊类型确定的基本算法。最后通过实例来验证本方法。更多还原

【Abstract】 Feature-based solid modeling techniques CAD system has been used for product structure design, while CAE system has been used for analysis of product mechanical properties. Obviously, the high integration of CAD and CAE will efficiently accomplish the product design process. Unfortunately, the existing CAD and CAE system inherently using different geometry engine and modeling accuracy exists no generic, unified model which could be used both for design and for analysis. Model transformation based on geometric model among different system usually lead to data loss and data redundancy.Aiming to the drawbacks of geometry model-based transformation, this paper adopt mesh model instead of geometry model to realise lossless data mapping from CAD to CAE system. Meanwhile it proposes a mesh optimization method toward meshes generated from CAD system, and extracts boundary feature information from the mesh. The research is primarily reflected in:1. Giving a review of research status about CAD/CAE integration at home and abroad, the merits and faults are analyed, then puting forward the research content and structure arrangement in this paper.2. Reseaching failure cause of the geometry model-based transformation in depth, introducing basic principle of lossless data mapping for mesh model-based transformation form CAD to CAE system. It also presents how to extract node and element information from CAD platform-UG NX5. It analyzes file format of mesh data in exiting CAE system and successfully realize data transformation from UG to ANSYS、Abaqus and so on.3. Using element transformation theory smooths tetrahedron mesh, introducing tetrahedron element quality measure rule, describing the simultaneous smoothing algorithm sequential smoothing algorithm, and verifying this method using unit sphere and modular hip endoprosthesis model. According to result compared with traditonal method shows the superiority of this method.4. Introducing basic theories of differential geometry, proposing the corrective method about ridge extracting including detection region of umbilicus, umbilicus detection, ridge detection and classification of ridge. Finally, using sevesal examples verify this method.更多还原