Documents disponibles écrits par cet auteur

EBSD studies of the stress-induced B2–B19′ martensitic transformation in NiTi tubes under uniaxial tension and compression / S.C. Mao in Acta materialia, Vol. 58 N° 9 (Mai 2010) 

Public ISBD [article]  in Acta materialia > Vol. 58 N° 9 (Mai 2010) . - pp. 3357–3366 Titre : EBSD studies of the stress-induced B2–B19′ martensitic transformation in NiTi tubes under uniaxial tension and compression Type de document : texte imprimé Auteurs : S.C. Mao, Auteur ; J.F. Luo, Auteur ; Z. Zhang, Auteur Année de publication : 2011 Article en page(s) : pp. 3357–3366 Note générale : Métallurgie Langues : Anglais (eng) Mots-clés : Shape  memory  alloys  (SMA)  Martensitic  phase  transformation  Electron  backscattering  diffraction  (EBSD)  In  situ Résumé : In situ electron backscattering diffraction (EBSD) investigations were conducted on polycrystalline NiTi tube specimens during tensile and compressive deformation. The long-range cooperative and catalytic martensitic transformation under tension induces the transformation to proceed in the form of helical Lüders band. Propagation of the band is closely related to the spatial distribution of the orientations of individual grains. In uniaxial compression, the larger variation in Schmid factors, and consequently the larger variation in the critical transformation stresses among grains, leads to a homogeneous martensitic transformation, and therefore the absence of the Lüders band. To interpret the observed tension–compression asymmetry, a crystallographic model of the critical transformation stress and transformation strain for polycrystalline NiTi under tension and compression is proposed. The model defines three crystallographic regions: tension-favorable, compression-favorable and neutral zones. The orientation population in which tensile strains are larger than compressive strains is much higher than that of orientations with higher compressive strains. For resolved shear stress, orientation populations favoring tension and compression do not show any great difference. DEWEY : 669 ISSN : 1359-6454 En ligne : http://www.sciencedirect.com/science/article/pii/S1359645410000959 [article] EBSD studies of the stress-induced B2–B19′ martensitic transformation in NiTi tubes under uniaxial tension and compression [texte imprimé] / S.C. Mao, Auteur ; J.F. Luo, Auteur ; Z. Zhang, Auteur . - 2011 . - pp. 3357–3366. Métallurgie Langues : Anglais (eng) in Acta materialia > Vol. 58 N° 9 (Mai 2010) . - pp. 3357–3366 Mots-clés : Shape  memory  alloys  (SMA)  Martensitic  phase  transformation  Electron  backscattering  diffraction  (EBSD)  In  situ Résumé : In situ electron backscattering diffraction (EBSD) investigations were conducted on polycrystalline NiTi tube specimens during tensile and compressive deformation. The long-range cooperative and catalytic martensitic transformation under tension induces the transformation to proceed in the form of helical Lüders band. Propagation of the band is closely related to the spatial distribution of the orientations of individual grains. In uniaxial compression, the larger variation in Schmid factors, and consequently the larger variation in the critical transformation stresses among grains, leads to a homogeneous martensitic transformation, and therefore the absence of the Lüders band. To interpret the observed tension–compression asymmetry, a crystallographic model of the critical transformation stress and transformation strain for polycrystalline NiTi under tension and compression is proposed. The model defines three crystallographic regions: tension-favorable, compression-favorable and neutral zones. The orientation population in which tensile strains are larger than compressive strains is much higher than that of orientations with higher compressive strains. For resolved shear stress, orientation populations favoring tension and compression do not show any great difference. DEWEY : 669 ISSN : 1359-6454 En ligne : http://www.sciencedirect.com/science/article/pii/S1359645410000959

Fluid streaming in micro/minibifurcating networks / Z. Zhang in Transactions of the ASME . Journal of fluids engineering, Vol. 131 N° 8 (Août 2009) 

Public ISBD [article]  in Transactions of the ASME . Journal of fluids engineering > Vol. 131 N° 8 (Août 2009) . - 08 p. Titre : Fluid streaming in micro/minibifurcating networks Type de document : texte imprimé Auteurs : Z. Zhang, Auteur ; M. Krafczyk, Auteur ; A. Fadl, Auteur Année de publication : 2009 Article en page(s) : 08 p. Note générale : fluids engineering Langues : Anglais (eng) Mots-clés : flow  streaming;  micro-/minichannel  networks;  oscillation Résumé : In this study, we investigate the phenomena of flow streaming in micro-/minichannel networks of symmetrical bifurcations using computer simulations with analytical validation. The phenomena of the flow streaming can be found in zero-mean velocity oscillating flows in a wide range of channel geometries. Although there is no net mass flow (zero-mean velocity) passing through the channels, the discrepancy in velocity profiles between the forward flow and backward flow causes fluid particles near the walls to drift toward one end while particles near the centerline to drift toward the opposite end. The unique characteristics of flow streaming could be used for various applications. The advantages include enhanced mixing, pumpless fluid propulsion, multichannel fluid distribution, easy system integration, and cost-effective operation. The results of computer simulations showed that oscillation amplitude is the dominant effect on streaming velocity in channel networks. Streaming velocity was directly proportional to the oscillation frequency and can be used as a cost-effective and reliable convective transport means when the particle diffusivity is less than the fluid kinematic viscosity. A considerable amount of work is needed to further study and understand the flow streaming phenomenon. En ligne : http://fluidsengineering.asmedigitalcollection.asme.org/issue.aspx?journalid=122 [...] [article] Fluid streaming in micro/minibifurcating networks [texte imprimé] / Z. Zhang, Auteur ; M. Krafczyk, Auteur ; A. Fadl, Auteur . - 2009 . - 08 p. fluids engineering Langues : Anglais (eng) in Transactions of the ASME . Journal of fluids engineering > Vol. 131 N° 8 (Août 2009) . - 08 p. Mots-clés : flow  streaming;  micro-/minichannel  networks;  oscillation Résumé : In this study, we investigate the phenomena of flow streaming in micro-/minichannel networks of symmetrical bifurcations using computer simulations with analytical validation. The phenomena of the flow streaming can be found in zero-mean velocity oscillating flows in a wide range of channel geometries. Although there is no net mass flow (zero-mean velocity) passing through the channels, the discrepancy in velocity profiles between the forward flow and backward flow causes fluid particles near the walls to drift toward one end while particles near the centerline to drift toward the opposite end. The unique characteristics of flow streaming could be used for various applications. The advantages include enhanced mixing, pumpless fluid propulsion, multichannel fluid distribution, easy system integration, and cost-effective operation. The results of computer simulations showed that oscillation amplitude is the dominant effect on streaming velocity in channel networks. Streaming velocity was directly proportional to the oscillation frequency and can be used as a cost-effective and reliable convective transport means when the particle diffusivity is less than the fluid kinematic viscosity. A considerable amount of work is needed to further study and understand the flow streaming phenomenon. En ligne : http://fluidsengineering.asmedigitalcollection.asme.org/issue.aspx?journalid=122 [...]

Oscillatory streaming flow based mini/microheat pipe technology / Z. Zhang in Journal of heat transfer, Vol. 132 N° 5 (Mai 2010) 

Public ISBD [article]  in Journal of heat transfer > Vol. 132 N° 5 (Mai 2010) . - pp. [055001-1/8] Titre : Oscillatory streaming flow based mini/microheat pipe technology Type de document : texte imprimé Auteurs : Z. Zhang, Auteur ; C. Liu, Auteur ; A. Fadl, Auteur Article en page(s) : pp. [055001-1/8] Note générale : Physique Langues : Anglais (eng) Mots-clés : Heat  pipe  Flow  streaming  Oscillation  flow  Bifurcation  Microchannel Index. décimale : 536 Chaleur. Thermodynamique Résumé : The sustained drive for faster and smaller micro-electronic devices has led to a considerable increase in power density. The ability to effectively pump and enhance heat transfer in mini-/microchannels is of immense technological importance. Using oscillatory flow to enhance the convective heat transfer coefficients in micro-/minichannels is one of many new concepts and methodologies that have been proposed. In this paper, a novel and simple concept is presented on oscillating streaming flow based mini/microheat pipe or heat spreader technology. Phenomena of the flow streaming can be found in zero-mean velocity oscillating flows in many channel geometries. Although there is no net mass flow (zero-mean velocity) passing through the channel, discrepancy in the velocity profiles between the forward and backward flows causes fluid particles near the walls to drift toward one end while particles near the centerline drift to the other end. This unique characteristic of flow streaming could be used for various applications. Some of the advantages include enhanced heat/mass transfer, pumpless fluid propulsion, multichannel fluid distribution, easy system integration, and cost-effective operation. Preliminary work has been conducted on scaling analysis, computer simulations, and visualization experiments of fluid streaming, propulsion, and multichannel distribution by flow oscillation in minitapered channels and channel networks. Results show that streaming flow has the potential to be used as a cost-effective and reliable heat pipe and/or as a heat spreader technique when fluid thermal conductivity is low. DEWEY : 536 ISSN : 0022-1481 En ligne : http://asmedl.aip.org/vsearch/servlet/VerityServlet?KEY=JHTRAO&smode=strresults& [...] [article] Oscillatory streaming flow based mini/microheat pipe technology [texte imprimé] / Z. Zhang, Auteur ; C. Liu, Auteur ; A. Fadl, Auteur . - pp. [055001-1/8]. Physique Langues : Anglais (eng) in Journal of heat transfer > Vol. 132 N° 5 (Mai 2010) . - pp. [055001-1/8] Mots-clés : Heat  pipe  Flow  streaming  Oscillation  flow  Bifurcation  Microchannel Index. décimale : 536 Chaleur. Thermodynamique Résumé : The sustained drive for faster and smaller micro-electronic devices has led to a considerable increase in power density. The ability to effectively pump and enhance heat transfer in mini-/microchannels is of immense technological importance. Using oscillatory flow to enhance the convective heat transfer coefficients in micro-/minichannels is one of many new concepts and methodologies that have been proposed. In this paper, a novel and simple concept is presented on oscillating streaming flow based mini/microheat pipe or heat spreader technology. Phenomena of the flow streaming can be found in zero-mean velocity oscillating flows in many channel geometries. Although there is no net mass flow (zero-mean velocity) passing through the channel, discrepancy in the velocity profiles between the forward and backward flows causes fluid particles near the walls to drift toward one end while particles near the centerline drift to the other end. This unique characteristic of flow streaming could be used for various applications. Some of the advantages include enhanced heat/mass transfer, pumpless fluid propulsion, multichannel fluid distribution, easy system integration, and cost-effective operation. Preliminary work has been conducted on scaling analysis, computer simulations, and visualization experiments of fluid streaming, propulsion, and multichannel distribution by flow oscillation in minitapered channels and channel networks. Results show that streaming flow has the potential to be used as a cost-effective and reliable heat pipe and/or as a heat spreader technique when fluid thermal conductivity is low. DEWEY : 536 ISSN : 0022-1481 En ligne : http://asmedl.aip.org/vsearch/servlet/VerityServlet?KEY=JHTRAO&smode=strresults& [...]