EVALUATION OF RESOURCE CHARACTERISTICS OF POWER EQUIPMENT PARTS UNDER THERMAL CYCLIC LOADING

The problem of assessing the strength and resource critical engineering facilities, operational properties which are characterized by multiparametric non-stationary thermo-mechanical effects, is discussed. main degradation mechanisms structural materials (metals their alloys) characteristic such objects considered. basic requirements for mathematical models these processes formulated. A model describing thermoplastic deformation accumulation fatigue damage during material mechanism thermal has been developed from position mechanics damaged medium (MPS). IPU consists three interrelated parts: relations that determine cyclic behavior material, taking into account dependence on destruction process; equations kinetics accumulation; criteria material. variant defining thermoplasticity based idea yield surface principle gradiency velocity vector plastic deformations to at loading point. This version state reflects effects process arbitrary complex trajectories combined thermomechanical loading. kinetic introduction a scalar parameter, energy principles takes formation, growth fusion microdefects under conditions. As criterion condition reaching value used. To assess degree reliability limits applicability ratios MPS, calculations were carried out numerical results obtained compared with data field experiments example specific applied problem. analysis features durability compact sample stress concentrators simulating operation parts in nozzle box steam turbine nuclear power plant (NPP) out. pulsations experimental data. It shown MPS qualitatively accuracy necessary quantitatively describes can be effectively used thermocyclic structures multiaxial disproportionate paths