基于3D有限元仿真的钻杆接头应力分析与集中系数研究OA

In drilling engineering,failures at the threaded connections of drill pipe joints account for up to 86%,making them the primary risk area for drill string failure.To conduct an in-depth analysis of joint stress distribution and concentration characteristics,this study,based on 3D finite element simulation,performed a comparative analysis of the stress in API standard single-shoulder and double-shoulder drill string joints under axial and torsional loads.Furthermore,the axial and torsional stress concentration coefficients for the NC50-type joint were calculated.The findings indicate that:the maximum stress in single-shoulder threads is concentrated at the root of the first thread in the thread engagement area;the maximum axial and shear stresses in double-shoulder threads are significantly lower than those in single-shoulder threads,with reductions of approximately 24%and 27.3%,respectively,exhibiting a more pronounced performance advantage,especially under high torque;the axial stress concentration coefficient for the NC50 joint is 4.21,and the torsional stress concentration coefficient is 3.73.The outcomes of this research provide a significant basis for the performance optimization design of drill pipe joints,precise stress calculation of the drilling system,and fatigue life prediction.