【作者】 詹雯；

【导师】 周来水；

【作者基本信息】 南京航空航天大学 ， 航空宇航制造工程， 2007， 硕士

【摘要】 近些年来,在飞机、汽车、造船、服装和玩具等设计及制造领域中,复杂曲面展开技术被越来越广泛地应用于坯料外形的计算和设计。随着计算机辅助设计(CAD)技术的发展和先进制造技术的采用,设计者可以借助辅助设计工具设计出多种外形美观的高质量曲面结构产品,这对坯料计算方法提出了新的要求。本文采用基于三角片和基于顶点两种曲面初始展开方法来实现复杂曲面的初始展开。对前人提出的基于弹簧-质点模型的展开优化算法进行了改进,实现了优化过程中时间步长的自适应选取;提出三角片翻转区域整体调整算法,快速有效地消除初始展开及优化过程中出现的翻转三角片;考虑材料性质对于展开平面网格形状的影响;在获得初始展开平面的基础上,得到规整的展开平面网格。在前人提出的基于网格角度的全局优化展开方法的基础上,本文提出了基于网格边长度的全局优化展开方法,简称LBF方法,来获得离散曲面展开后的平面网格形状。为提高LBF方法求解效率,提出加速LBF方法。与以往的展开方法相比,LBF方法更加稳定,并且能够控制展开的局部精度。应用上述展开技术,本文基于Windows NT/2000/XP系统和CATIA V5平台应用Visual C++开发工具开发了“复杂曲面近似展开系统”软件模块,实现了复杂曲面的展开计算、展开图形自动绘制、展开误差云图显示和平面网格数据文件自动生成。结构信息数据文件采用CATIA系统的DAT文件格式,二维展开平面图采用CATIA V5数据格式显示;误差文件(.ero文件)由系统生成并通过误差云图显示模块加以显示。更多还原

【Abstract】 In recent years, in some manufacturing fields such as the production of airplanes, vehicle, ships, clothes, shoes and toys, complex surface flattening technology has been wildly applied in the design and calculate of blank materials. With the development of computer aided design technology (CAD) and the adoption of advanced manufacturing technology, designer could design many curve-structure products with high-quality and graceful form. However, this brings new demands to the traditional calculation of blank.This thesis tries to realize the initial shape which has the same topology structure as the complex surface by the use of two initial flattening methods based on triangulate and vertex. The writer makes some improvement and adjustments to the develop optimization method based on Spring-Mass system, realizing the time step’s self-adaptive choose in the process of optimization. Besides, the writer also presents the Global Adjustment Algorithm for the rolling region of triangulates, which could eliminate the rolling triangulate in the initial projection and optimization quickly and effectively for an orderly developed mesh surface on the basis of the initial flattening pattern of the surface. Efforts are also devoted to the study of material in the process of consistent with the actual situation in the deformation of the material flattening.On the basis of the global optimization of angles in the surface, a new approach is proposed- the global optimization of lengths in the surface, to get the form of mesh surface after the flattening of discrete curve surface. This method is called LBF(Length-Based Flattening)method for short. LBF defines the flattening problem as an optimization problem of the constraint problems whose paradigms are all the length of the mesh surface of the discrete curve surface. Compared with the previous approaches, LBF method is more stable and more capable of controlling the local precision in flattening process.With the above technologies, the writer develops a module named“Approximately Flattening System for Complex Surface”based on Windows NT/2000/XP and CATIA V5 and with the help of Visual C++, thus realizing the flattening of complex surface, automatic drawing of the flattened design and the auto-generation of error cloud atlas reality and data for surface. The program deals with interfaces: the structure information data is the DAT from CATIA V5 system; 2-dimension flattening model is shown by the CATIA V5; the error file is automatically created by system and error map is shown by the error display module use the corresponding error file.更多还原