Strength of Lock Joint of Turbine Blades at High Temperatures

The problem of the stress-strain state of the lock joint of rotor blades for the intermediate pressure cylinder of a steam turbine is solved by the finite-element method for supercritical steam parameters (over 240 atm and 565 degrees C). The proposed method involves the stage-by-stage determination of the stress-strain state of lock joint, the 3D problem statement, given contact interaction of elements, temperature loads, and plastic and creep deformations of the elements. The stress-strain state influenced by the plastic deformation of the elements in the joint is described using the plastic flow theory. The results of studying the effect of creep on the stress-strain state of the lock joint are presented. The largest increase in creep strains is observed during the first 50,000 hours. The variations in the nature and level of contact stress on the bearing surfaces of the joint elements due to the redistribution of the stresses and strains in the structure as a whole are shown.