The sealing performance of premium connection mainly depends on the form of main sealing structure, the size of sealing interference and the sealing effect of auxiliary sealing structure. Considering the above three factors, the sealing performance of premium connection can be improved to the greatest extent.
The finite element method has a great advantage in analyzing the object with complex geometry and complex material performance. For the casing thread joint with complex structure and deformation often exceeding the elastic range, the finite element method is an ideal tool for analysis. At the same time, in order to verify the accuracy of finite element results, full-scale test method is also necessary.
The sealing performance analysis of premium connection is an elastic-plastic contact problem which combines the material nonlinearity and the boundary condition nonlinearity, and the contact analysis is the difficulty. In the analysis, the contact boundary is described by the direct constraint method. The basic principle is to track the object's motion track. Once the contact is detected, the motion constraint and node force required by the contact are directly applied to the contact nodes as the boundary conditions. This method does not increase the degree of freedom of the system, and can directly select the contact elements on the contact boundary. The load and displacement of the nodes are determined according to the contact compatibility conditions.