一、引言三通结构是管道系统中常见的部件。压力容器上开大孔并外接直管也是一种三通结构。对于薄壁小接管的三通,已有一些解析方法能得到良好的结果。但对于厚壁或大口径接管的三通,则很难求得解析解。随着有限元方法和计算机技术的发展,这个问题得到了有效地解决。早在六十年代就有人用三角形板壳元来分析三通应力。后来也有不少人用各种板壳 I. INTRODUCTION The three-way structure is a common component in the pipeline system. Large pressure vessel and open a large straight pipe is also a three-way structure. For the thin-walled small take over the tee, some analytical methods have been able to get good results. But for thick-walled or large diameter take over the tee, it is difficult to obtain analytic solution. With the development of finite element method and computer technology, this problem has been effectively solved. As early as the 1960s, some people used the triangle plate shell element to analyze the tee stress. Then there are many people with a variety of shell