抽油杆方凸过渡段缺陷应力集中因数和容限

抽油杆方凸过渡段部位在制造和使用中经常会出现引发断裂的各种缺陷，影响抽油杆的正常使用。在常出现缺陷的部位建立了横向凹槽、中间凹坑和边棱凹坑三组有代表性的缺陷模型，利用有关文献给出的平面模型的有限元法计算结果以及平面模型与轴对称模型间的模型比因数和凸缘影响因数等，求得方凸过渡段的最危险部位三组不同缺陷模型应力集中因数表达式，用三维趋势面描绘了应力集中因数的变化规律，求得缺陷容限方程，绘制了典型的容限图，为有缺陷杆的修复使用和判废提供了理论依据。

Stress concentration factor and tolerance of flaws on sucker rod wrench square transition area

In the light of the flaws on the rod wrench square transition area, three groups of typical flaw models, i. e. the cross groove model, mid-position groove model and edge pit model, are established, and by using the results of finite element calculation with the plane model and the relevant model ratio factor and flange influence factor, the equations of stress concentration factors for three groups of models of flaws on the most critical part of the wrench square transition area are worked out. And the variation pattem of the stress concentration factors is described by the three-dimensional trend diagram, and the equations for the flaw toleranes are derived and typical tolerance diagram is drawn.