Documents disponibles écrits par cet auteur

Coupled thermomechanical fatigue tests for simulating load conditions in cooled turbine parts / Roland Mücke in Transactions of the ASME . Journal of engineering for gas turbines and power, Vol. 134 N° 5 (Mai 2012) 

Public ISBD [article]  in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 134 N° 5 (Mai 2012) . - 06 p. Titre : Coupled thermomechanical fatigue tests for simulating load conditions in cooled turbine parts Type de document : texte imprimé Auteurs : Roland Mücke, Auteur ; Klaus Rau, Auteur Année de publication : 2012 Article en page(s) : 06 p. Note générale : Génie mécanique Langues : Anglais (eng) Mots-clés : Fatigue  testing  Gas  turbines  Lead  Nickel  alloys  Stress  relaxation  Superalloys Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Modern heavy-duty gas turbines operate under hot gas temperatures that are much higher than the temperature capability of nickel superalloys. For that reason, advanced cooling technology is applied for reducing the metal temperature to an acceptable level. Highly cooled components, however, are characterized by large thermal gradients resulting in inhomogeneous temperature fields and complex thermomechanical load conditions. In particular, the different rates of stress relaxation due to the different metal temperatures on hot gas and cooling air exposed surfaces lead to load redistributions in cooled structures, which have to be considered in the lifetime prediction methodology. In this context, the paper describes coupled thermomechanical fatigue (CTMF) tests for simultaneously simulating load conditions on hot and cold surfaces of cooled turbine parts (Beck et al., 2001, “Experimental Analysis of the Interaction of Hot and Cold Volume Elements During Thermal Fatigue of Cooled Components Made From AISI 316 L Steel,” Z. Metallkunde, 92, pp. 875–881 and Rau et al., 2003, “Isothermal Thermo-mechanical and Complex Thermo-mechanical Fatigue Tests on AISI 316 L Steel—A Critical Evaluation,” Mater. Sci. Eng., A345, pp. 309–318). In contrary to standard thermomechanical fatigue (TMF) testing methods, CTMF tests involve the interaction between hot and cold regions of the parts and thus more closely simulates the material behavior in cooled gas turbine structures. The paper describes the methodology of CTMF tests and their application to typical load conditions in cooled gas turbine parts. Experimental results are compared with numerical predictions showing the advantages of the proposed testing method. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000134000005 [...] [article] Coupled thermomechanical fatigue tests for simulating load conditions in cooled turbine parts [texte imprimé] / Roland Mücke, Auteur ; Klaus Rau, Auteur . - 2012 . - 06 p. Génie mécanique Langues : Anglais (eng) in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 134 N° 5 (Mai 2012) . - 06 p. Mots-clés : Fatigue  testing  Gas  turbines  Lead  Nickel  alloys  Stress  relaxation  Superalloys Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Modern heavy-duty gas turbines operate under hot gas temperatures that are much higher than the temperature capability of nickel superalloys. For that reason, advanced cooling technology is applied for reducing the metal temperature to an acceptable level. Highly cooled components, however, are characterized by large thermal gradients resulting in inhomogeneous temperature fields and complex thermomechanical load conditions. In particular, the different rates of stress relaxation due to the different metal temperatures on hot gas and cooling air exposed surfaces lead to load redistributions in cooled structures, which have to be considered in the lifetime prediction methodology. In this context, the paper describes coupled thermomechanical fatigue (CTMF) tests for simultaneously simulating load conditions on hot and cold surfaces of cooled turbine parts (Beck et al., 2001, “Experimental Analysis of the Interaction of Hot and Cold Volume Elements During Thermal Fatigue of Cooled Components Made From AISI 316 L Steel,” Z. Metallkunde, 92, pp. 875–881 and Rau et al., 2003, “Isothermal Thermo-mechanical and Complex Thermo-mechanical Fatigue Tests on AISI 316 L Steel—A Critical Evaluation,” Mater. Sci. Eng., A345, pp. 309–318). In contrary to standard thermomechanical fatigue (TMF) testing methods, CTMF tests involve the interaction between hot and cold regions of the parts and thus more closely simulates the material behavior in cooled gas turbine structures. The paper describes the methodology of CTMF tests and their application to typical load conditions in cooled gas turbine parts. Experimental results are compared with numerical predictions showing the advantages of the proposed testing method. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000134000005 [...]

A cyclic life prediction approach for directionally solidified nickel superalloys / Roland Mücke in Transactions of the ASME . Journal of engineering for gas turbines and power, Vol. 132 N° 5 (Mai 2010) 

Public ISBD [article]  in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 132 N° 5 (Mai 2010) . - 07 p. Titre : A cyclic life prediction approach for directionally solidified nickel superalloys Type de document : texte imprimé Auteurs : Roland Mücke, Auteur ; Piyawan Woratat, Auteur Année de publication : 2011 Article en page(s) : 07 p. Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Blades  Creep  fracture  Fracture  toughness  Gas  turbines  Remaining  life  assessment  Superalloys Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : The performance of heavy duty gas turbines is closely related to the material capability of the components of the first turbine stage. In modern gas turbines single crystal (SX) and directionally solidified (DS) nickel superalloys are applied, which, compared with their conventionally cast version, hold a higher cyclic life and a significantly improved creep rupture strength. SX and DS nickel superalloys feature a significant directional dependence of the material properties. To fully exploit the material capability, the anisotropy needs to be accounted for in both the constitutive and lifing model. In this context, the paper addresses a cyclic life prediction procedure for DS materials with transverse isotropic material symmetry. Thereby, the well-known local approaches to fatigue life prediction of isotropic materials under uniaxial loading are extended toward materials with transverse isotropic properties under multiaxial load conditions. As part of the proposed methodology, a Hill type function is utilized for describing the anisotropic failure behavior. The coefficients of the Hill surface are determined from the actual multiaxial loading, material symmetry, and anisotropic fatigue strength of the material. In this paper we first characterize the anisotropy of DS superalloys. We then present the general mathematical framework of the proposed lifing procedure. Later we discuss a validation of the cyclic life model by comparing the measured and predicted fatigue lives of the test specimens. Finally, the proposed method is applied to the cyclic life prediction of a gas turbine blade. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000132000005 [...] [article] A cyclic life prediction approach for directionally solidified nickel superalloys [texte imprimé] / Roland Mücke, Auteur ; Piyawan Woratat, Auteur . - 2011 . - 07 p. Génie Mécanique Langues : Anglais (eng) in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 132 N° 5 (Mai 2010) . - 07 p. Mots-clés : Blades  Creep  fracture  Fracture  toughness  Gas  turbines  Remaining  life  assessment  Superalloys Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : The performance of heavy duty gas turbines is closely related to the material capability of the components of the first turbine stage. In modern gas turbines single crystal (SX) and directionally solidified (DS) nickel superalloys are applied, which, compared with their conventionally cast version, hold a higher cyclic life and a significantly improved creep rupture strength. SX and DS nickel superalloys feature a significant directional dependence of the material properties. To fully exploit the material capability, the anisotropy needs to be accounted for in both the constitutive and lifing model. In this context, the paper addresses a cyclic life prediction procedure for DS materials with transverse isotropic material symmetry. Thereby, the well-known local approaches to fatigue life prediction of isotropic materials under uniaxial loading are extended toward materials with transverse isotropic properties under multiaxial load conditions. As part of the proposed methodology, a Hill type function is utilized for describing the anisotropic failure behavior. The coefficients of the Hill surface are determined from the actual multiaxial loading, material symmetry, and anisotropic fatigue strength of the material. In this paper we first characterize the anisotropy of DS superalloys. We then present the general mathematical framework of the proposed lifing procedure. Later we discuss a validation of the cyclic life model by comparing the measured and predicted fatigue lives of the test specimens. Finally, the proposed method is applied to the cyclic life prediction of a gas turbine blade. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000132000005 [...]