Computer simulation of creep of a cylinder in contact with rods of semi-cylindrical cross-section

Abstract

The paper is devoted to the description of the problem statement, the modeling approach, and the obtained results on the creep of a thick tube when it is in contact with rods of semi-cylindrical cross-section, which are located symmetrically to its center. An overview of research papers made in the direction of creep contact modeling, including the FEM use, is presented. The formulation of the problem is presented taking into account finite strains and displacements. The contact conditions are described, the variational functional used for the finite element formulation of the problem is presented. Due to the existing symmetry of the geometric parameters and boundary conditions of the problem, it was solved using the plane strain statement. The area of FEM discretization is the fourth part of the tube cross-section, which is in contact with the cross-section of the rod in the form of a half circle. The results of verification studies performed to assess the reliability of solving the creep problem for the cylinder loaded with internal pressure are presented. Different models are discussed for describing the contact interaction, which can be used in the ANSYS software. The advantages of using the Normal Lagrange Method are shown. The tube contact deformation during creep for 10,000 hours was analyzed. The distributions of the components of the stress-strain state obtained by computer modeling along the sections of the contacting elements and the plot of the redistribution of von Mises equivalent stress at the point of contact are presented. The characteristics obtained by calculations of the deformed state of the surface of the cylindrical tube, which arises due to the influence of the contacting rod, are discussed. An approximation was made and analytical expressions of the dependence of the von Mises stress and the length of the contact line on time were presented. The obtained results of solving the creep problem indicate that within approximately 1.25 years due to the contact of the tube with the rods, dent-type defects are formed on its surface.