FINITE ELEMENT ANALYSIS FOR THE CONTACT STATE OF THE TOP AND BOTTOM CYLINDERS OF THE TURBINE STRUCTURE

In this paper, the finite element softwareMSC/NASTRAN is adopted to calculate and analyze the stress anddeformation distributions of the cylinder. The effect of thetemperature field, and the joint action of the temperature field and theinternal pressure are analyzed with particular emphasis onthe linking surface-halved surface on the bolt ofthe half cylinder in the top and bottom.The 3D body model for finite element analysis and the simulating modelfor all link bolts are established. Analysis results show that the thermal stress is the main part of the stress in the cylinder, as compared with the stresscaused by the internal pressure.When the difference of the inside and outside wall temperatures has reached100^\circC, the maximum stress is 1230MPa inside the cylinder body, in the position of the stress concentration, and the stress levels in most places of the cylinder body are about the 600~700MPa. When the outside wall temperature is 25℃, the maximum stress is about1080MPainside the cylinder body, the stress levels in the most parts of thecylinder body are about 100MPa. Therefore, when the temperaturedifference of the inside and outside walls of the cylinder was reduced, the stressinside the cylinder body can be efficiently reduced.The analysis shows that the maximum axial deformation is about 2.55mm inthe cylinder body, the maximum horizontal deformation is about 2.02mm.The maximum deformation in the Z axis is about 1.24mm.A separation appears upon the halved surface, but the separationdegree is small and in the order of 103mm.