Finite Element Analysis of the Stress of Premium Connection Loaded by Combined Loads

Considering the helix angle and using the elasto-plastic contact finite element method, a 2-D and 3-D finite element models are established by the finite element analysis software ANSYS. The stress distribution of special thread tubing joints under different combined loads are analyzed and compared. The analysis results shows that the effect of different composite loads on the joint strength and sealing performance of oil casing joint are different. Under different internal pressure of combined load, the joint strength of oil casing joint has little influence, but with the increase of pipe pressure, the leakage resistance of tubing joint is enhanced. Under combined load, with the increase of axial tension, the stress of oil pipe joint which is generated in the initial meshing position and near the end of the thread is much higher than that of middle thread and large axial tension easily lead to thread failure phenomenon. Besides, it is important to compare the calculated stress contour curve with 2D and 3D finite element models which are the reason why comparative analysis is used.