Numerical assessment of thick walled power plant components under creep fatigue load with advanced models for deformation and lifetime

Abstract

Renewable energy sources are changing the operation mode of conventional power plants significantly. Load changes cause fatigue deformation and damage, where traditionally creep effects dominated. In thick walled components the fatigue is concentrated on the inside (where temperature changes are quickest), but through plastification and stress rearrangement during operation the deformation behaviour of the entire component is affected. In this work, the time and temperature dependent deformation of components is described by finite element analysis based on a viscoplastic deformation Chaboche type model. Creep fatigue damage is evaluated by a mechanism based creep fatigue crack growth model and applied by a post-processor program with automatic load cycle detection. An introduction to verification efforts within the HWT-II test rig (at GKM Mannheim) and by full scale component test (MACPLUS project) are given.