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General aspects of yield stress fluids - Terminology and definition of viscosity / Martin Boisly in APPLIED RHEOLOGY, Vol. 24, N° 1 (2014)
[article]
Titre : General aspects of yield stress fluids - Terminology and definition of viscosity Type de document : texte imprimé Auteurs : Martin Boisly, Auteur ; Markus Kästner, Auteur ; Jörg Brummund, Auteur ; Volker Ulbricht, Auteur Année de publication : 2014 Article en page(s) : 11 p. Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Fluides non newtoniens
Fluides, Mécanique des
Rhéologie
ViscositéTags : 'Fluide de stress' 'Viscosité différentielle' Viscosité apparente' 'Contrainte d'équilibre' 'Elément friction' 'Élément Bingham' Index. décimale : 532.05 Mécanique des fluides et des liquides - Dynamique (cinétique et cinématique) Résumé : This work contributes to general theoretical aspects of yield stress fluids with significance for practical phenomenological material modeling. It introduces a terminology so that the material class 'yield stress fluid' is defined and can be distinguished from the terms `solid' and liquide. This new material classification is based on two criteria, the equilibrium relation and the flow function. In line with this terminology, an experimental procedure for classifying the material behavior is presented. The second key aspect of this paper is a discussion on the proper definition of the term 'viscosity'. The benefit of the differential viscosity over the dynamic viscosity in case of non-Newtonian fluids in general is worked out. This is shown by the most ele-mentary yield stress fluid, the friction element, because it is the basis of the yield stress concept. Its constitutive equations are given for positive as well as negative strain rates and are also able to represent the preyield behavior. The theory presented in this article is also applied to the Maxwell, Kelvin-Voigt, and Bingham element to demonstrate the working principle. Note de contenu : - SPLIT OF THE TOTAL STRESS INTO AN EQUILIBRIUM AND OVERSTRESS
- DIFFERENTIAL VISCOSITY DEFINED BY THE STEADY STATE MATERIAL RESPONSE TO A CONSTANT STRAIN RATE LOADING
- CLASSIFICATION OF MATERIAL BEHAVIOR INTO THREE TYPES : SOLIDS, LIQUIDS AND YIELD STRESS FLUIDS
- DISCUSSION OF THE DIFFERENTIAL VISCOSITY AND DEMONSTRATION OF THE FUNCTIONALITY OF THE MATERIAL CLASSIFICATION BY STANDARD AND EXTENDED RHEOLOGICAL ELEMENTS : Constitutive equations of standard rheological elements used to illustrate the theoretical statements of this article - Illustrating the benefit of a differential viscosity by standard rheological elements - Application of the material classification to standard rheological elements - Application of the material classification to extended rheological elementsRéférence de l'article : 14578 DOI : 10.3933/ApplRheol-24-14578 Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=21555
in APPLIED RHEOLOGY > Vol. 24, N° 1 (2014) . - 11 p.[article]Réservation
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Code-barres Cote Support Localisation Section Disponibilité 16175 - Périodique Bibliothèque principale Documentaires Disponible New Technique to Capture Viscoelastic Changes in Hair Induced by Mechanical Stress / S. B. Hornby in IFSCC MAGAZINE, Vol. 5, N° 2 (04-05-06/2002)
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Titre : New Technique to Capture Viscoelastic Changes in Hair Induced by Mechanical Stress Type de document : texte imprimé Auteurs : S. B. Hornby, Auteur ; Nigel J. P Winsey, Auteur ; Stephen P. Bucknell, Auteur Année de publication : 2002 Article en page(s) : p. 93-97 Note générale : Bibliogr. Langues : Anglais (eng) Tags : 'Cyclic testing' Fatigue 'Elastic modulus' Resiliency 'Tensile stress' 'Hair breakage' Index. décimale : 668.5 Parfums et cosmétiques Résumé : In a previous article [1], we have described the mechanical fatigue behaviour of hair fibers subjected to intermitted tensile deformations using the Cyclic Tester (Dia-Stron, Ltd., Andover, UK) in order to mimic stresses encountered during grooming procedures. The instrument imparts repeated tensile load cycles to the hair and records the numbers of cycles at the break point of each hair fiber. The distributions of the number of cycles required to cause hair fiber breakage were analyzed using the Weibull distribution and the beneficial effect of certain conditioners was discussed.
The Cyclic Tester is also capable of recording load-elongation data for the hair fiber during the load cycles. In this study, we captured the load elongation data at selected load cycles of very damaged tip ends of single hair fibers and compared this data to that obtained for the undamaged root end of the same fiber using the Cyclic Tester. The changes in the hair fiber elastic and viscoelastic characteristics of very damaged and unaltered hair as a function of a number of prior deformations were compared. The instrument was enable to give a portrait of the viscoelastic changes in hair during repetitive stress.Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=10651
in IFSCC MAGAZINE > Vol. 5, N° 2 (04-05-06/2002) . - p. 93-97[article]Réservation
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Code-barres Cote Support Localisation Section Disponibilité 003874 - Périodique Bibliothèque principale Documentaires Disponible On the stress distribution at scratching of thin film structures / Fredrik Wredenberg in JOURNAL OF COATINGS TECHNOLOGY AND RESEARCH, Vol. 7, N° 5 (09/2010)
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Titre : On the stress distribution at scratching of thin film structures Type de document : texte imprimé Auteurs : Fredrik Wredenberg, Auteur ; Per-Lennart Larsson, Auteur Année de publication : 2010 Article en page(s) : p. 623-635 Note générale : Bibliogr. Langues : Américain (ame) Catégories : Rayures
Revêtements:PeintureTags : Revêtement Rayure 'Structures film/substrat' 'Distribution du stress' 'Analyse des éléments finis' Délamination Index. décimale : 667.9 Revêtements et enduits Résumé : Scratching of thin film/substrate structures is studied theoretically and numerically. In most cases, the material behavior of the film as well as the substrate is described by classical elastoplasticity accounting for large deformations; further, pressure-sensitive flow models are considered. The main efforts are devoted toward an understanding of the influence from the film/substrate boundary on the stress distribution at scratching but for comparative reasons, scratching of homogeneous materials are also studied and pertinent results presented. Among other things, the results are discussed in relation to delamination initiation and growth at scratching. The numerical investigation is performed using the finite element method, and the numerical strategy is discussed in some detail. The most important finding given by the present study is that high shear stresses are the main driving force for delamination initiation and growth along the film/substrate interface. It was also noted that the influence from pressure-sensitive flow on the stress fields related to delamination initiation is small, both quantitatively and qualitatively. DOI : 10.1007/s11998-010-9242-9 En ligne : https://link.springer.com/content/pdf/10.1007%2Fs11998-010-9242-9.pdf Format de la ressource électronique : Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=9916
in JOURNAL OF COATINGS TECHNOLOGY AND RESEARCH > Vol. 7, N° 5 (09/2010) . - p. 623-635[article]Réservation
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Code-barres Cote Support Localisation Section Disponibilité 012448 - Périodique Bibliothèque principale Documentaires Disponible