异径管三维实体模型的计算机建模方法

Three-Dimensional Modeling of Reducer

介绍了管道配件异径管的结构分类及两端带直管的3 种常见结构的三维实体模型计算机绘图方法。在一串圆圈组成的骨架上铺上蒙皮的方法可以准确描述异径弯管的结构,且结构两端面与等壁厚的直管端面直接相连即可以获得完满的接头模型;通过大小两个正圆锥体相减可以准确描述同心异径管的结构,但结构两端面与等壁厚的直管需重叠相连,并把相交割出的多余边角删除后才能获得完满的接头模型;偏心异径管的壁厚变化与圆周角有关,无论其横截面与本身的轴线垂直还是与两端接管的轴线垂直,均不是等壁厚的圆形,其简便的近似建模方法是直接连接间距等于管件高度的两个大小口径的直管端面。这些模型应用到有限元数值分析中,对各种外载荷作用时的应力分布状况有直观的显示。

Structure types and their modeling method of three-dimension solid about three kinds general reducers with pipes in two ends are provided. The outer and inner surfaces of reducing elbow/bend are constructed by skinning the wire-frame consisting of a set of circular sections, and the junctions about their ends with equal thick pipes are well. The concentric reducers may be constructed by subtracting the smaller circular cone with the bigger one. But, the junctions about their ends with equal thick pipes must be overlapped in first and then the superfluous parts on the ends should be deleted at last. The eccentric reducers are difficult to accurate constructed because their cross sections are not the circular sections with equal thick in circumferential. A simple and easy and similar method is directly to link up the two end surfaces of pipe that the eccentric reducers should glue to. These models may be used to accomplish finite element analysis of reducer so as to get a visible understanding about the stress distribution while they are subject to load.