Thermo-Mechanical Fatigue of Thick-Walled Components of Power Devices

Abstract

The main purpose of this work is to determine the mechanical behaviour of power plant components operating under mechanical and thermal loading. Computer FEM modelling of temperature strain and stress fields along with temperature measurements have been applied as the methods of research. The stress-strain diagrams for the selected points of plant components have been determined. It is readily apparent from the stress-strain characteristics that under unsteady operating conditions, components analysed in this paper, especially in the case of boiler restarts, may operate with transient thermal stresses which sometimes reach values higher than the yield point. Consequently, a thermo-mechanical fatigue process takes place in the materials of the components in question. This paper seeks to justify the necessity of the application of design methods which take into consideration the influence of TMF processes on the durability of highly reliable pressure vessels.