绘制六面体单元任意剖面温度分布云图的一种新方法

New Method for Plotting Moire Fringes of Temperature Distribution on Arbitrary Sections of Hexahedral Elements

目的绘制六面体单元任意剖面温度场云图的关键是确定剖面覆盖像素的自然坐标,笔者将介绍一种确定剖面覆盖像素自然坐标的精确简洁的方法.方法正方体母元被均匀划分为m×m×m个小正方体,利用小立方体顶点的自然坐标及形值函数计算实际坐标系中对应点的坐标,若实际坐标系中对应点在剖面上,则进一步求出温度,利用温度求出颜色,最后对应的像素设置为求出的颜色.遍历所有小正方体的顶点以后,便得到剖面上温度分布云图.结果该方法已经用于笔者开发的钢筋混凝土结构火灾反应数值模拟软件TFIELD的后处理器之中,实现了建筑构件任意剖面温度分布云图绘制.结论应用实践表明,笔者提出的方法精度高,速度快,易于编程,是一种绘制三维温度场任意剖面云图的理想方法.

The key to plotting moire fringes of temperature distribution on a section of a hexahedral element is to calculate the nature coordinates of pixels spanned by the section on screen. An accurate and efficient method for calculating nature coordinates of pixels is presented in this paper. A cubic parent element was evenly subdivided into m × m× m sub-cubes, and then the vertices of the sub-cubes were scanned one by one. The natural coordinates of a vertex were used to calculate the coordinates corresponding point in world coordinate system. If the corresponding point was on the section, then the temperature of the corresponding point was calculated using the node temperature and shape functions. The color value of the corresponding pixel on screen was gotten from pre-designed function relation between color and temperature. After all vertices of the sub-cubes were scanned, the moire fringe of temperature distribution on the section of the hexahedral element was plotted. The new method suggested in this paper has been employed in the postprocessor of TFIELD for thermal analysis of reinforced concrete structures exposed to fires developed by authors. Ex- amples illustrate that the suggested method is accurate, effective, easily implemented, and is an ideal approach to produce high quality moire fringes on arbitrary section of a hexahedral element.