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机械毕业设计论文

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机械毕业设计134基于UG的螺旋桨的曲面造型 068105303吴苑,机械毕业设计论文

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I 基于 UG的螺旋桨的 曲面造型 摘要 ： 船 用螺旋桨是一类典型的自由曲面零件， 它 的曲面形状和制造精度直接决定了船舶的推进效率和噪音的大小，而自由曲面造型方法的研究将有助于螺旋桨水动力性能的优化 。 曲面造型是计算机图形学和计算机辅助几何设计(Computer Aided Geometric Design)的一项重要内容，主要研究在计算机图象系统的环境下对曲面的表示、设计、显示和分析 。经过多年的不断发展，现在它已经形成了以 Bezier 和 B 样条方法为代表的参数化特征设计和隐式代数曲面表示这两类方法为主体，以插值 (Interpolation) 、拟合 (Fitting) 、逼近(Approximation)这三种手段为骨架的几何理论体系。 本文首先介绍了 UG 曲面建模和造型的一般方法和步骤，然后 介绍了一些船泊螺旋桨叶元体的相关知识 以及螺旋桨的切面几何特性 ，最后采用 UG/Open GRIP 的方法及 B 样条拟合来生成螺旋桨桨叶曲线 。 UG OpenGRIP 是 Unigraphics（简称 UG） CAD CAM 软件包中的一个模块，是 Unigraphics 软件的二次开发工具之一。 UG OpenGRIP 语言用来创建类似 FORTRAN 语言一样的程 序，与 Unigraphics系统集成。本文采用 UG/Open GRIP 对给定的点进行编辑，并且编辑后的文件可以用记事本打开和编辑，然后在三维建模的时候可以通过插入采用 UG/Open GRIP编辑后的文件中的点。 本文在深入分析螺旋桨 构成及其 曲面成型原理的基础上，将设计时给定的桨叶曲面的切面数据转化为笛卡尔坐标系中的坐标，利用 B 样条方法对截面数据点插值并加密，得到足够的数据点，进而利用最小二乘法拟合出螺旋桨桨叶曲面，通过调整偏离权和光滑权顺利得到了理想的二阶连续的桨叶曲面 。本文 在 介绍螺旋桨 CAD 造型的两种方法 的 基础上，着重详细地介绍了螺旋桨在 UG 环境下从点到线，由线拟合成曲面，进而由曲面生产三维实体的全过程。 关键 字 ： 船用螺旋桨；自由曲面； B 样条拟合； CAD 三维建模 Based on UG propellers surface modelling Abstract： The propeller used by ship is a kind of typical component of free surface, its surface shape and the manufacture precision have decided ships propulsive efficiency and the noise size directly, but the free surface modelling methods research will be helpful to the propeller hydrodynamic force performance nts II optimization. The surface modeling is an important content of the computer graphics and the computer auxiliary geometry design, main research under computer image systems environment to surface expression, design, demonstration and analysis. After many year continuous development, it already had formed now take Bezier and B Spline curve Fitting method as representatives parametrization characteristic design and the implicit expression algebraic surface expressed that these two kind of methods are the main bodies, take interpolation (Interpolation), fits (Fitting), to approach (Approximation) these three methods as skeletons geometry system info. This article first introduced the UG surface modelling and the modelling general method and the step, then introduced some ships anchor the blade Yuan Ti related knowledge as well as propellers section geometry characteristic, finally uses UG/Open GRIP the method and the B spline fit produces the propeller paddle blade curve. UG/OpenGRIP is a CAD/CAM software packages module in Unigraphics (i.e. UG), is one re-development tools of Unigraphics softwares. The UG/OpenGRIP language uses for to found the similar FORTRAN language same procedure, with the Unigraphics system integration. This article uses UG/Open GRIP to the spot which assigns to carry on the edition, and after editing the document may use the memorandum to open and to edit, then in three dimensional modelling time may use UG/Open after the insertion the GRIP edition in the document spot.The paddle blade surface section data which this article when the thorough analysis propeller constitution and in the surface formation principles foundation, will design assigns to transform as the Cartesian coordinate systems in coordinate, and encrypts using the B transect method to the section data point interpolation, obtains the enough data point, then the use least squares method fits the propeller paddle blade surface, obtained the ideal second-order continual paddle blade surface smoothly through the adjustment deviation power and the smooth power. This article in the introduction propeller CAD modellings two methods foundations, introduced in detail emphatically the propeller under the UG environment from the spot to the line, fits the surface by the line, t