The Experts below are selected from a list of 309 Experts worldwide ranked by ideXlab platform
Alain Köster - One of the best experts on this subject based on the ideXlab platform.
-
Viscoplastic behaviour of metals deformed at high Temperature, Application to tension-compression cycles
Journal of Materials Science, 2008Co-Authors: Vladimir Gantchenko, Patrice Jouinot, Alain KösterAbstract:A mechanical modelling is proposed in order to describe viscoplastic behaviour without hardening of a nickel-base super alloy loaded at high Temperature (900 °C) with strain rates varying within a wide range (from 10−1 to 10−4 s−1). A mathematical law is associated to the viscoplastic model; the parameters of the law are identified from monotonic biaxial tests of membranes loaded by pressure of inert gas (disk pressure testing under helium). The viscoplastic law provides calculated stresses with accuracy better than 1% at the highest strain rates and 4% at the lowest strain rates; the identified yield stress is a logarithmical function of strain rate as for other metallic alloys studied in the bibliography. The parameters identified from biaxial tensile tests of disks have been successfully used to calculate the stresses during stabilized tension–compression loops of cylindrical specimens. The proposed experimental method and behaviour model are interesting because the disk biaxial testing is much more easily performed at high Temperature than the tension–compression testing of cylindrical specimens.
-
elasto viscoplastic behavior of the ferritic stainless steel aisi 441 en 1 4509 from room Temperature to 850 c
Journal of Astm International, 2006Co-Authors: Laurent Bucher, Pierre-olivier Santacreu, Alain Köster, Luc RémyAbstract:In order to predict the thermomechanical fatigue (TMF) damage of stainless steel parts submitted to thermal loading, the elasto-viscoplastic behavior has to be described accurately in a wide range of Temperature, strain, and strain rate levels. The study is done on a stabilized ferritic stainless steel grade equivalent to AISI 441 or EN 1.4509 standard which is used more and more in high Temperature Application up to 950°C, for example, in exhaust manifolds, heat exchanger, burners, or water-boiler device. The elasto-viscoplastic model proposed by Chaboche is chosen and identified on the basis of isothermal cyclic tests including relaxation and graduated cyclic strain tests performed under air at 300, 650 and 850°C. The validation procedure was performed afterward by comparison with stabilized behavior under nonisothermal conditions, especially in-phase, out-of-phase, and diamond TMF cycles. Results of simulation show very good fitting with the experimental curves which would lead to a more accurate fatigue life prediction.
-
Elasto-Viscoplastic Behavior of the Ferritic Stainless Steel AISI 441-EN 1.4509 from Room Temperature to 850°C
Journal of ASTM International, 2006Co-Authors: Laurent Bucher, Pierre-olivier Santacreu, Alain Köster, Luc RémyAbstract:In order to predict the thermomechanical fatigue (TMF) damage of stainless steel parts submitted to thermal loading, the elasto-viscoplastic behavior has to be described accurately in a wide range of Temperature, strain, and strain rate levels. The study is done on a stabilized ferritic stainless steel grade equivalent to AISI 441 or EN 1.4509 standard which is used more and more in high Temperature Application up to 950°C, for example, in exhaust manifolds, heat exchanger, burners, or water-boiler device. The elasto-viscoplastic model proposed by Chaboche is chosen and identified on the basis of isothermal cyclic tests including relaxation and graduated cyclic strain tests performed under air at 300, 650 and 850°C. The validation procedure was performed afterward by comparison with stabilized behavior under nonisothermal conditions, especially in-phase, out-of-phase, and diamond TMF cycles. Results of simulation show very good fitting with the experimental curves which would lead to a more accurate fatigue life prediction.
Luc Rémy - One of the best experts on this subject based on the ideXlab platform.
-
elasto viscoplastic behavior of the ferritic stainless steel aisi 441 en 1 4509 from room Temperature to 850 c
Journal of Astm International, 2006Co-Authors: Laurent Bucher, Pierre-olivier Santacreu, Alain Köster, Luc RémyAbstract:In order to predict the thermomechanical fatigue (TMF) damage of stainless steel parts submitted to thermal loading, the elasto-viscoplastic behavior has to be described accurately in a wide range of Temperature, strain, and strain rate levels. The study is done on a stabilized ferritic stainless steel grade equivalent to AISI 441 or EN 1.4509 standard which is used more and more in high Temperature Application up to 950°C, for example, in exhaust manifolds, heat exchanger, burners, or water-boiler device. The elasto-viscoplastic model proposed by Chaboche is chosen and identified on the basis of isothermal cyclic tests including relaxation and graduated cyclic strain tests performed under air at 300, 650 and 850°C. The validation procedure was performed afterward by comparison with stabilized behavior under nonisothermal conditions, especially in-phase, out-of-phase, and diamond TMF cycles. Results of simulation show very good fitting with the experimental curves which would lead to a more accurate fatigue life prediction.
-
Elasto-Viscoplastic Behavior of the Ferritic Stainless Steel AISI 441-EN 1.4509 from Room Temperature to 850°C
Journal of ASTM International, 2006Co-Authors: Laurent Bucher, Pierre-olivier Santacreu, Alain Köster, Luc RémyAbstract:In order to predict the thermomechanical fatigue (TMF) damage of stainless steel parts submitted to thermal loading, the elasto-viscoplastic behavior has to be described accurately in a wide range of Temperature, strain, and strain rate levels. The study is done on a stabilized ferritic stainless steel grade equivalent to AISI 441 or EN 1.4509 standard which is used more and more in high Temperature Application up to 950°C, for example, in exhaust manifolds, heat exchanger, burners, or water-boiler device. The elasto-viscoplastic model proposed by Chaboche is chosen and identified on the basis of isothermal cyclic tests including relaxation and graduated cyclic strain tests performed under air at 300, 650 and 850°C. The validation procedure was performed afterward by comparison with stabilized behavior under nonisothermal conditions, especially in-phase, out-of-phase, and diamond TMF cycles. Results of simulation show very good fitting with the experimental curves which would lead to a more accurate fatigue life prediction.
Ping Fan - One of the best experts on this subject based on the ideXlab platform.
-
Enhanced thermoelectric properties of Sb2Te3/CH3NH3I hybrid thin films by post-annealing
Inorganic Chemistry Frontiers, 2020Co-Authors: Shuo Chen, Yuexing Chen, Jingting Luo, Guangxing Liang, Xianghua Zhang, Zhuanghao Zheng, Ping FanAbstract:In this work, to improve the ZT value of Sb2Te3, a novel concept of inorganic-organic hybridization is presented and Sb2Te3/CH3NH3I hybrid thin films have been prepared via a post-annealing involved sequential sputtering/evaporation method. The results show that the crystallinity of the thin films is greatly improved after post-annealing with preferential orientations of (006) and (009) at an appropriate Temperature, leading to an obvious enhancement of electrical conductivity. Additionally, the hybrid thin films show uniform nano-sized grainy structures and the organic component CH3NH3I has been successfully incorporated into the hybrid system in a stable state, thus resulting in an increase of the Seebeck coefficient and decrease of the thermal conductivity based on the energy filtering effect. As expected, a maximum room-Temperature ZT value of 0.56 for the Sb2Te3/CH3NH3I hybrid thin film annealed at 573 K can be obtained. This outcome further demonstrates great potential for the inorganic-organic hybrid thin film in low Temperature Application scenarios.
Toru Kawanishi - One of the best experts on this subject based on the ideXlab platform.
-
freeze drying of proteins with glass forming oligosaccharide derived sugar alcohols
International Journal of Pharmaceutics, 2010Co-Authors: Saori Kadoya, Kahori Fujii, Ken-ichi Izutsu, Chikako Yomota, Etsuo Yonemochi, Katsuhide Terada, Toru KawanishiAbstract:Abstract Physical properties and protein-stabilizing effects of sugar alcohols in frozen aqueous solutions and freeze-dried solids were studied. Various frozen sugar alcohol solutions showed a glass transition of the maximally freeze-concentrated phase at Temperatures ( T g ′s) that depended largely on the solute molecular weights. Some oligosaccharide-derived sugar alcohols (e.g., maltitol, lactitol, maltotriitol) formed glass-state amorphous cake-structure freeze-dried solids. Microscopic observation of frozen maltitol and lactitol solutions under vacuum (FDM) indicated onset of physical collapse at Temperatures ( T c ) several degrees higher than their T g ′s. Freeze-drying of pentitols (e.g., xylitol) and hexitols (e.g., sorbitol, mannitol) resulted in collapsed or crystallized solids. The glass-forming sugar alcohols prevented activity loss of a model protein (LDH: lactate dehydrogenase) during freeze-drying and subsequent storage at 50 °C. They also protected bovine serum albumin (BSA) from lyophilization-induced secondary structure perturbation. The glass-forming sugar alcohols showed lower susceptibility to Maillard reaction with co-lyophilized l -lysine compared to reducing and non-reducing disaccharides during storage at elevated Temperature. Application of the oligosaccharide-derived sugar alcohols as alternative stabilizers in lyophilized protein formulations was discussed.
-
Freeze-drying of proteins with glass-forming oligosaccharide-derived sugar alcohols.
International journal of pharmaceutics, 2010Co-Authors: Saori Kadoya, Kahori Fujii, Ken-ichi Izutsu, Chikako Yomota, Etsuo Yonemochi, Katsuhide Terada, Toru KawanishiAbstract:Physical properties and protein-stabilizing effects of sugar alcohols in frozen aqueous solutions and freeze-dried solids were studied. Various frozen sugar alcohol solutions showed a glass transition of the maximally freeze-concentrated phase at Temperatures (T(g)'s) that depended largely on the solute molecular weights. Some oligosaccharide-derived sugar alcohols (e.g., maltitol, lactitol, maltotriitol) formed glass-state amorphous cake-structure freeze-dried solids. Microscopic observation of frozen maltitol and lactitol solutions under vacuum (FDM) indicated onset of physical collapse at Temperatures (T(c)) several degrees higher than their T(g)'s. Freeze-drying of pentitols (e.g., xylitol) and hexitols (e.g., sorbitol, mannitol) resulted in collapsed or crystallized solids. The glass-forming sugar alcohols prevented activity loss of a model protein (LDH: lactate dehydrogenase) during freeze-drying and subsequent storage at 50 degrees C. They also protected bovine serum albumin (BSA) from lyophilization-induced secondary structure perturbation. The glass-forming sugar alcohols showed lower susceptibility to Maillard reaction with co-lyophilized L-lysine compared to reducing and non-reducing disaccharides during storage at elevated Temperature. Application of the oligosaccharide-derived sugar alcohols as alternative stabilizers in lyophilized protein formulations was discussed.
Laurent Bucher - One of the best experts on this subject based on the ideXlab platform.
-
elasto viscoplastic behavior of the ferritic stainless steel aisi 441 en 1 4509 from room Temperature to 850 c
Journal of Astm International, 2006Co-Authors: Laurent Bucher, Pierre-olivier Santacreu, Alain Köster, Luc RémyAbstract:In order to predict the thermomechanical fatigue (TMF) damage of stainless steel parts submitted to thermal loading, the elasto-viscoplastic behavior has to be described accurately in a wide range of Temperature, strain, and strain rate levels. The study is done on a stabilized ferritic stainless steel grade equivalent to AISI 441 or EN 1.4509 standard which is used more and more in high Temperature Application up to 950°C, for example, in exhaust manifolds, heat exchanger, burners, or water-boiler device. The elasto-viscoplastic model proposed by Chaboche is chosen and identified on the basis of isothermal cyclic tests including relaxation and graduated cyclic strain tests performed under air at 300, 650 and 850°C. The validation procedure was performed afterward by comparison with stabilized behavior under nonisothermal conditions, especially in-phase, out-of-phase, and diamond TMF cycles. Results of simulation show very good fitting with the experimental curves which would lead to a more accurate fatigue life prediction.
-
Elasto-Viscoplastic Behavior of the Ferritic Stainless Steel AISI 441-EN 1.4509 from Room Temperature to 850°C
Journal of ASTM International, 2006Co-Authors: Laurent Bucher, Pierre-olivier Santacreu, Alain Köster, Luc RémyAbstract:In order to predict the thermomechanical fatigue (TMF) damage of stainless steel parts submitted to thermal loading, the elasto-viscoplastic behavior has to be described accurately in a wide range of Temperature, strain, and strain rate levels. The study is done on a stabilized ferritic stainless steel grade equivalent to AISI 441 or EN 1.4509 standard which is used more and more in high Temperature Application up to 950°C, for example, in exhaust manifolds, heat exchanger, burners, or water-boiler device. The elasto-viscoplastic model proposed by Chaboche is chosen and identified on the basis of isothermal cyclic tests including relaxation and graduated cyclic strain tests performed under air at 300, 650 and 850°C. The validation procedure was performed afterward by comparison with stabilized behavior under nonisothermal conditions, especially in-phase, out-of-phase, and diamond TMF cycles. Results of simulation show very good fitting with the experimental curves which would lead to a more accurate fatigue life prediction.
