Publikationsserver der RWTH Aachen University
Validierung des nichtlinearen Verformungsverhaltens von großen Einkristall-Gasturbinenschaufeln aus CMSX-4
Abstract
dc:descriptionThe achievement of high efficiency in large-based stationary gas turbines for electric power generation requires increased gas temperatures. Gas temperatures higher than 1300°C can only be handled using air cooled structures to keep the metal temperatures below 1000°C. Only single crystal superalloys have the required creep strength and thermo-mechanical fatigue resistance. Single crystal blades exhibit a highly anisotropic deformation behaviour and are subjected to triaxial stress fields induced by complex cooling systems. Consequently the prediction of their deformation behaviour requires constitutive equations based on multiaxial formulations. The microstructural evolution of Gamma/Gamma' superalloys during the service time modifies the material properties and has therefore to be taken into account in the constitutive equations. For the modelling of the anisotropic, viscoplastic behaviour of single crystal blades where the evolution of the microstructure has also to be considered. The microstructural dependant constitutive equations are discussed for a structural analysis of a big single crystal model blade. The orthotropic Hills potential, whose anisotropy coefficients are connected to the edge length of the Gamma’-particles, is applied. If the shape of Gamma’-particles remain cubic, for example, in creep testing at low temperatures (up to about 850°C), the microstructure-dependent potential leads to the cubic version of the Hills potential. For the multiaxiale confirmation of the model, experiment with internally single crystal model blades were carried out. The prediction is in good agreement with creep results for <001>-orientated specimens. If the Gamma’-particles coalesce to form rafts, the viscoplastic response of the superalloy is continuously modified. For the mathematical analysis the constitutive equations were implemented into the Finite-Elemente-Code ABAQUS. A two dimensional mesh was used. The implementation of the model in Finte-Element-Codes requires a numerical treatment of the constitutive equations with respect to the given interface of the used code.
Degree
thesis:*- Grantor dc:publisher
- Publikationsserver der RWTH Aachen University
- Year dc:date
- 2001
Author and committee
dc:creator, dc:contributor.*- Author dc:creator
-
- Steinhaus, Thomas
- Contributors dc:contributor
-
- Schubert, Florian
Subjects
dc:subject × 8Rights
dc:rights- Statement dc:rights
-
- info:eu-repo/semantics/openAccess
- Language dc:language
- ger
Identifiers
dc:identifier.*- OAI identifier oai:identifier
- oai:publications.rwth-aachen.de:57154