Abstract
Transient regimes arising during start-ups, shut-downs and change of operation regime in steam power plants cause unsteady thermal and mechanical loading with time in turbine components resulting in non-uniform strain and stress distribution. Thus accurate knowledge of stresses, caused by various loading conditions, is required for the integrity and life assessment for the turbine components. Although materials of steam turbine components deform inelastically at high temperature, only elastic calculations are currently performed from a conservative point of view for safety and simplicity. Although numerous models have been proposed to describe the viscoplastic (time-dependent) behavior, these models are rather elaborate and difficult to incorporate into finite element code to simulate the loading of complex structures. In this paper, the total lifetime for steam turbine components was calculated by combining the viscoplastic constitutive equation and the ABAQUS finite element code. The viscoplasitc analysis was particularly focused on simplified constitutive equations with linear kinematic hardening that is simple enough to be used effectively in computer simulation. The von Mises stress distribution of HIP turbine rotor was calculated during cold start-up rotor and a reasonable number of cycle was obtained from the equation of Langer.
