Documents disponibles écrits par cet auteur

Microstructure and high-temperature deformation behavior of Al2O3–TiO2 obtained from ultra-high-pressure densification of metastable powders / J. Suffner in Acta materialia, Vol. 59 N° 20 (Décembre 2011) 

Public ISBD [article]  in Acta materialia > Vol. 59 N° 20 (Décembre 2011) . - pp. 7592–7601 Titre : Microstructure and high-temperature deformation behavior of Al2O3–TiO2 obtained from ultra-high-pressure densification of metastable powders Type de document : texte imprimé Auteurs : J. Suffner, Auteur ; T. Scherer, Auteur ; D. Wang, Auteur Année de publication : 2012 Article en page(s) : pp. 7592–7601 Note générale : Métallurgie Langues : Anglais (eng) Mots-clés : Sintering  Nanocomposite  Superplasticity  Ceramics  Crystallization Résumé : Metastable alumina composite powders with 13 wt.% titania were produced by plasma spraying using liquid nitrogen quenched substrates. The material consisted of a mixture of Al2O3 in a distorted spinel structure and a large amount of amorphous phases. High-pressure–high-temperature sintering below the crystallization temperature of the amorphous phase yielded a crystalline/amorphous composite that was used for creep experiments. During heating to the desired testing temperature, crystallization occurred and an in situ composite composed of corundum and rutile was obtained. This material exhibited superior deformation behavior compared to conventionally processed alumina materials. Comparably low temperatures of 1100 °C could be utilized to achieve plastic deformation of the material under a pressure of 50 MPa. Coble grain boundary creep with n = 1 and a low activation energy for diffusion of 390 kJ mol−1 was assumed to be the deformation mechanism. ISSN : 1359-6454 En ligne : http://www.sciencedirect.com/science/article/pii/S1359645411006628 [article] Microstructure and high-temperature deformation behavior of Al2O3–TiO2 obtained from ultra-high-pressure densification of metastable powders [texte imprimé] / J. Suffner, Auteur ; T. Scherer, Auteur ; D. Wang, Auteur . - 2012 . - pp. 7592–7601. Métallurgie Langues : Anglais (eng) in Acta materialia > Vol. 59 N° 20 (Décembre 2011) . - pp. 7592–7601 Mots-clés : Sintering  Nanocomposite  Superplasticity  Ceramics  Crystallization Résumé : Metastable alumina composite powders with 13 wt.% titania were produced by plasma spraying using liquid nitrogen quenched substrates. The material consisted of a mixture of Al2O3 in a distorted spinel structure and a large amount of amorphous phases. High-pressure–high-temperature sintering below the crystallization temperature of the amorphous phase yielded a crystalline/amorphous composite that was used for creep experiments. During heating to the desired testing temperature, crystallization occurred and an in situ composite composed of corundum and rutile was obtained. This material exhibited superior deformation behavior compared to conventionally processed alumina materials. Comparably low temperatures of 1100 °C could be utilized to achieve plastic deformation of the material under a pressure of 50 MPa. Coble grain boundary creep with n = 1 and a low activation energy for diffusion of 390 kJ mol−1 was assumed to be the deformation mechanism. ISSN : 1359-6454 En ligne : http://www.sciencedirect.com/science/article/pii/S1359645411006628

Sensitivity analysis and shape optimization of a hole in a vibrating rectangular plate for eigenfrequency maximization / D. Wang in Journal of engineering mechanics, Vol. 138 N° 6 (Juin 2012) 

Public ISBD [article]  in Journal of engineering mechanics > Vol. 138 N° 6 (Juin 2012) . - pp.662-674 Titre : Sensitivity analysis and shape optimization of a hole in a vibrating rectangular plate for eigenfrequency maximization Type de document : texte imprimé Auteurs : D. Wang, Auteur Année de publication : 2012 Article en page(s) : pp.662-674 Note générale : Mécanque appliquée Langues : Anglais (eng) Mots-clés : Sensitivity  analysis  Hole  shape  optimization  Rectangular  plate  Rayleigh-Ritz  method  Eigenfrequency  maximization Résumé : A hole inside a rectangular thin plate is optimized for maximization of an eigenfrequency of the structure. The shape of the hole is represented by an ellipse parametrization to guarantee a smooth curve along the boundary; and the hole’s center position, semiaxes, and rotation are treated as shape design variables. The Rayleigh-Ritz approach is applied to constitute the vibration frequency equation such that an exact procedure can be presented for the frequency sensitivity analysis. The hole shape optimization is performed by using a combined mathematical programming algorithm with different search directions for two sets of design variables in relation to the constraint of the hole’s size. In addition, a simple optimality criterion is provided for the optimum profile design of the internal hole of a given area. Several illustrative examples demonstrate the validity and effectiveness of the design sensitivity analysis and the proposed optimization method. ISSN : 0733-9399 En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29EM.1943-7889.0000376 [article] Sensitivity analysis and shape optimization of a hole in a vibrating rectangular plate for eigenfrequency maximization [texte imprimé] / D. Wang, Auteur . - 2012 . - pp.662-674. Mécanque appliquée Langues : Anglais (eng) in Journal of engineering mechanics > Vol. 138 N° 6 (Juin 2012) . - pp.662-674 Mots-clés : Sensitivity  analysis  Hole  shape  optimization  Rectangular  plate  Rayleigh-Ritz  method  Eigenfrequency  maximization Résumé : A hole inside a rectangular thin plate is optimized for maximization of an eigenfrequency of the structure. The shape of the hole is represented by an ellipse parametrization to guarantee a smooth curve along the boundary; and the hole’s center position, semiaxes, and rotation are treated as shape design variables. The Rayleigh-Ritz approach is applied to constitute the vibration frequency equation such that an exact procedure can be presented for the frequency sensitivity analysis. The hole shape optimization is performed by using a combined mathematical programming algorithm with different search directions for two sets of design variables in relation to the constraint of the hole’s size. In addition, a simple optimality criterion is provided for the optimum profile design of the internal hole of a given area. Several illustrative examples demonstrate the validity and effectiveness of the design sensitivity analysis and the proposed optimization method. ISSN : 0733-9399 En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29EM.1943-7889.0000376