Research on the design and performance of drill pipe joints based on fracture mechanics methods

In actual drilling operations, fatigue failure of drill pipe joints primarily occurs at the threaded connections, significantly increasing drilling costs. Given the severe vibrations and abnormal wear experienced by drill pipes under complex working conditions, a three-dimensional finite element model of drill pipe joints was developed. This model is based on fracture mechanics theory, the principle of virtual work, the Von Mises yield criterion, and contact nonlinear theory, while also incorporating the influence of thread taper angles. By evaluating both straight and tapered threads with varying tooth profile angles, optimal structural parameters were determined. The results demonstrate that a 45-degree tooth profile angle represents the optimal configuration, meeting the fundamental requirements for water exploration in coal mines.