Papers by Keyword: Stress-Strain Behaviour

Abstract: Binary and ternary composites based on isotactic polypropylene and low-density polyethylene in a wide range of ratios without and with filler content have been investigated. Micron-scale vegetable cellulosic components initiating biological degradation have been used as fillers for polymeric composites. The analysis of stress-strain behaviour of the composites has shown a non-additive dependency of elongation and tensile strength at break on blends composition. Based on this study results the composition and structure of polymeric phase of binary and ternary composites, as well as dimensional parameters of filler particles have a significant impact on stress-strain behaviour of the materials. The main regularities determining materials mechanical properties have been discovered, that, in turn, could be used for predicting service behaviour of composites under investigation.

Abstract: The paper discusses the issue of the influence of the growth of the operation parameters of power plant components on the fatigue phenomena that take place under mechanical and thermal loading. The loading characteristics have been taken as measurements results in industrial conditions. Stress-strain characteristics of such components, which take into consideration the changeable properties of materials subject to fatigue, have been described. The hardening processes of the materials, which are assumed to be used in designed power plants, have also been discussed. The aim of the paper is the description of the mechanical behaviour of the power plant components taking into consideration the real industrial conditions of their operation and changeable mechanical properties of the components’ materials.

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.