钻铤螺纹的有限元分析及应力分散槽优化设计

针对钻井技术进步带来的井下钻铤的服役条件更加苛刻、失效更加严重的问题，对钻铤螺纹失效问题进行了深入分析，找出引起钻铤螺纹失效的主要原因和失效的关键部位，利用大型三维实体建模软件Pro/E和有限元分析软件ANSYS分别对API标准钻铤螺纹进行实体建模和强度分析，得出了钻铤螺纹在不同工况、不同结构条件下的等效应力分布情况，并对ZTNC56-80型钻铤螺纹应力分散槽进行了最优化研究，找出了其最优值，并指出应力的变化与过渡圆角变化不是线性对应关系，在改进钻铤螺纹应力分散槽结构时，不能单纯以增大结构过渡圆角为手段，从而为改进钻铤螺纹应力分散槽结构提供了科学依据。

Drill Collar Thread FEA and Stress-relief Grooves Optimization Design

Along with the progress of drilling technology, the work condition of the borehole drill collar becomes harsher. Main reasons and vital area of causing drill collar screw failure are discovered by further analysis on these problems. This research analyzes the strength of API standard connection screw thread with large scale three-dimensional solid modeling software Pro/E and large scale finite element analysis software ANSYS, as well as the distribution of von Mises stress under different work condition and structure. Optimal research of stress-relief grooves of ZTNC56-80 drill collar thread is conducted and the optimal value found out. It is pointed out that the stress trend and the fillet of structure is not linear relation, when improving stress-relief groove structure of drill collar thread, we can not simply rely on increasing the fillet of structure, thus this research offers scientific basis for ameliorating stress-relief grooves of drill collar thread.