圆螺纹套管接头应力分布规律研究

STUDY ON STRESS DISTRIBUTION AT ROUND CASING THREAD CONNECTIONS

根据弹塑性力学理论建立圆螺纹套管接头的计算模型 ,利用有限元分析和全尺寸实验相结合的方法 ,详细分析套管接头在使用工况 (包括上扣、上扣后加拉伸载荷、上扣后加内压载荷等 )下的应力分布规律 ,指出载荷在各个螺纹牙上分布的不均匀性是制约套管接头性能的主要原因 ,提出改进接头应力状态、减少应力集中的主要措施。研究结果提高了对套管接头应力水平的认识 ,对改进套管连接螺纹设计 。

According to the theory of elastic mechanics and plastic mechanics, a finite element method (FEM) model is developed to study the stress on round casing thread connections. Detailed analysis is given on the stress distribution of the connections under all kinds of work conditions, such as makeup process, makeup and pulling, makeup and inner pressure, by calculating the contact stress in thread with FEM. Moreover, the stress in periphery of the connections is measured under the same conditions by full scale test. The results show that load distribution is not uniform on each thread and this is the most important reason for the poor performance of the ordinary connections. On the bases of the analysis, several methods are presented to reduce the peak stress and optimize the load distribution on the threads. More clear understanding about the stress distribution at round casing thread connections can be obtained from the results presented and thus it can be taken as references in improving the design of casing thread so as to improving the quality of the connections.