双台肩钻杆接头三维力学分析

建立了双台肩钻杆接头的三维有限元模型，利用显式动力学有限元方法分析了双台肩钻杆接头在上扣扭矩、轴向拉力和弯矩作用下的力学特性。相比二维轴对称模型，三维有限元模型可以考虑螺纹的螺旋升角，有效地模拟螺纹接头的上扣特性。计算结果表明，上扣扭矩的作用使得接头在螺纹牙、主台肩、副台肩处产生一定的预紧力，从而实现公扣、母扣间的过盈配合；轴向拉力使得螺纹牙上的接触压力上升而主台肩、副台肩上的接触压力下降，这一方面加重了螺纹牙的负担，另一方面也影响了接头的密封性能；在弯矩的作用下，钻杆接头的应力分布呈现出明显的非对称特性。此外，在上扣扭矩和轴向拉力作用下，各螺纹牙的承载很不均匀，两端的几牙螺纹承担了大部分的载荷，而中间段螺纹牙仅承担了小部分载荷。

Three-dimensional mechanical analysis of the double-shouldered tool joint

The present paper established a three-dimensional finite element model of the double-shouldered tool joint,and analyzed mechanical behaviors of the tool joint under make-up torque,axial tension and bending moment by means of the explicit dynamic finite element method.Compared with a two-dimensional axisymmetric model,the three-dimensional finite element model can effectively simulate the make-up behaviors of threaded connection by taking the helix ascending angle of screw thread into consideration.The results show that the make-up torque can produce a certain preload of the threaded connection on the mating surface of threaded teeth,primary shoulder and secondary shoulder,which implements the interference fit between male and female threads.Axial tension increases the contact pressure on threaded teeth but decreases that on the primary and secondary shoulders,which,on one hand,aggravates the load of threaded teeth,and on the other hand,affects the sealing performance of tool joint.The stress distribution of tool joint takes on a distinct asymmetric property under the bending moment.Besides,the load of individual threaded tooth is unevenly distributed under make-up torque and axial tension,the most load is sustained by several threaded teeth at the both ends of the tool joint,while intermediate threaded teeth sustain only a less load.