三通应力比较复杂,主管与支管交叉处有一次应力和二次应力,目前有关强度的计算方法基本上都是经验性的,但在理论分析方面[1,2,3,4]已经肯定了几点:(1)采用塑性失效准则和极限分析方法;(2)对于延性材料,非连续部分在最大载荷作用下允许有少量的 Tee stress is more complex, there is a primary stress and secondary stress at the intersection of the supervisor and the branch pipe. At present, the calculation methods of strength are basically all empirical, but in theory analysis [1,2,3,4] have been affirmed When: (1) using plastic failure criteria and limit analysis methods; (2) for ductile materials, non-continuous part of the maximum load allows a small amount of