Contact Interaction of Turbine Blade Interlock Elements Under Creep.

The effect of the creep of materials of a structure on the nature of the contact interaction between its elements during long-term operation is investigated. The problem of the stress-strain state of the rotor blade interlock for the medium-pressure cylinder of a steam turbine for ultrasupercritical steam parameters (over 240 at and 565°C) is solved using a finite element software package. As a model of creep, a modified model of creep with hardening is considered. The methodology for solving the thermal contact problem of interaction between the interlock elements under creep conditions is based on the application of a contact layer model. The calculation is made for the case of the total loads of the centrifugal forces of blades and the temperature field in which the structural element is operated. The results on the distribution of total strains, equivalent stresse,s and contact stresses during long-term operation are analyzed. The points of time, upon reaching which the permissible strength characteristics of the materials used were exceeded, were determined. A change in the nature and level of contact stresses on the bearing surfaces of interlock elements due to the redistribution of the stress-strain state of the structure as a whole is shown. The moments of the appearance of detachment and absence of contact stresses on individual contact surfaces were determined. The results obtained are compared with the data from the operation, during which the structure was damaged. [ABSTRACT FROM AUTHOR]