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Viscoelasticity - Wikipedia, the free encyclopedia Viscoelastic material models are frequently used to describe the behaviour of (soft) human tissue, plastics, soil, etc. Commonly used viscoelastic models are the Kelvin material and Maxwell material. Scientists defined this material as viscoelastic because it exhibited the characteristics of a viscous liquid and an elastomeric solid. Linear viscoelasticity is when the function is separable in both creep response and load. en.wikipedia.org /wiki/Viscoelasticity   (314 words)

Tissue Viscoelasticity   (Site not responding. Last check: 2007-10-22) We demonstrate via continuum concepts of nonlinear viscoelasticity that differences in rate between creep and relaxation phenomenologically occur when the nonlinearity is of a strain-stiffening type, i.e. Although causal mechanisms associated with viscoelastic tissue behavior are complex, continuum concepts demonstrated in this study appear capable of interrelating creep and relaxation with fidelity. Viscoelastic damping, tan delta, in bone exhibits a broad minimum at frequencies 1 to 100 Hz. pec.engr.wisc.edu /news/news021122.html   (384 words)

Viscoelasticity notes The mathematical formulation of viscoelasticity theory is presented in the following chapters with the aim of enabling prediction of the material response to arbitrary load histories. For example, viscoelastic shoe insoles are useful in reducing mechanical shocks transmitted to the bones and joints. Viscoelasticity is of interest in materials science, metallurgy, and solid state physics since it is causally linked to a variety of microphysical processes and can be used as an experimental probe of those processes. silver.neep.wisc.edu /~lakes/VEnotes.html   (1265 words)

What is blood viscoelasticity Blood is a viscoelastic fluid and its rheological properties, viscosity and elasticity, depend on the rate of flow or shear rate. In this region the viscoelasticity of the blood is dominated by the deformability of the red blood cells. As an example, the viscoelasticity of an individual's blood with sickle cell disease is markedly different from the viscoelasticity of normal blood. www.vilastic.com /FAQ_Blood.htm   (1219 words)

Viscoelasticity. Viscoelastic materials A theoretical study of viscoelastic properties of composites is presented with the aim of identifying structures which give rise to a combination of high stiffness and high loss tangent. The dynamic response of isotropic composites of two viscoelastic isotropic phases mixed in arbitrary proportions is considered in the frequency range where the acoustic wavelength is much larger than the inhomogeneities and the properties of the isotropic composite can be described by complex bulk and shear moduli. Experimental studies of dynamic (internal friction) and transient viscoelastic response were conducted at 24 deg C on gamma InSn alloy, and high frequency studies were conducted to extend the frequency range for eutectic InSn. silver.neep.wisc.edu /~lakes/VE.html   (3832 words)

Viscoelasticity   (Site not responding. Last check: 2007-10-22) Anomalous viscoelasticity near the isotropic-nematic phase transition in liquid... Rolling migration and viscoelasticity of Staphlyococcus aureus biofilm microcolo... Viscoelasticity and diffusional properties of colloidal model dispersions... www.scienceoxygen.com /material/200.html   (253 words)

Principles of Rheology and its Measurement Techniques   (Site not responding. Last check: 2007-10-22) Viscoelastic concepts such as complex modulus, storage modulus, loss modulus, relaxation modulus, phase angle, dynamic viscosity, creep compliance and complex viscosity are defined and a mathematical approach to the relation between the different concepts is given. Viscoelastic flow models such as the Maxwell and the Kelvin models are introduced. Linear viscoelastic measurement methods are presented, such as oscillation, relaxation and creep and the measurement methods are illustrated by several worked examples. www.calmia.se /pages/adva.html   (756 words)

[No title]   (Site not responding. Last check: 2007-10-22) Because there is no specific equation for viscoelasticity, the equation for viscosity is used, and the viscoelasticity is measured in viscosity-equivalent units, giving a Newtonian equivalent of the combination of viscosity and elasticity found in a non- Newtonian fluid sample. The portions of the determined viscoelasticity attributed to the viscosity and to the elasticity depend upon the thickness of the fluid sample (density, not breadth). The present invention relies on several known conditions to test for viscoelasticity, one of which is that the surface area of the fluid sample is consistent, that is, that it does not change from test to test. www.wipo.int /cgi-pct/guest/getbykey5?KEY=03/86199.031023&ELEMENT_SET=DECL   (7774 words)

Effect of Biochemical Components on Rheologic Properties of Nasal Mucus in Chronic Sinusitis -- MAJIMA et al. 160 (2): ... The effect of biochemical components on the viscoelasticity of nasal mucus from 24 patients with chronic sinusitis (CS) was The viscoelasticity of the nasal mucus was determined with an oscillating sphere magnetic rheometer (5). Table 2 presents the results of the linear regression analyses of viscoelasticity measured at frequencies of 1 and 10 Hz versus the biochemical parameters. ajrccm.atsjournals.org /cgi/content/full/160/2/421   (3129 words)

AUT - Viscoelasticity   (Site not responding. Last check: 2007-10-22) To investigate the viscoelastic properties of muscle in unimpaired, injured and neuromuscular diseased states. This study investigates whether the viscoelastic properties of the plantar flexor muscles during passive stretching are affected by alterations in the position of the trunk and pelvis. The purpose of this study is to examine the effects of exercise in a restricted range of knee joint motion on viscoelastic properties of the hamstring muscles across a larger range of motion. www.aut.ac.nz /research/research_institutes/prrc/research_activities/viscoelasticity.htm   (514 words)

Plasma Viscosity & Blood Viscoelasticity Major shifts in the viscoelasticity of blood have been found to be associated with such pathologies as myocardial infarction, peripheral vascular disease, cancer and diabetes [5,6,7]. Since aggregation[9,10] and deformability[11,12] are key factors in the viscoelasticity of blood, the structural organization of cells that affects blood flow must be evaluated in terms of its contribution to the viscoelastic properties of blood, which in vivo determine the pressure-to-flow relationships in the vessels. In this region, the viscoelasticity is strongly influenced by the deformability of red blood cells. www.vilastic.com /tech10.html   (1250 words)

Alibris: Viscoelasticity A molecular approach to the fundamentals of viscoelastic behavior in polymers, bridging the gap between introductory accounts and advanced research level monographs. It begins with an introduction to phenomena observed in viscoelastic flows, the formulation of mathematical equations to model such flows, and the behavior of various models in simple flows. Viscoelastic properties of nearly monodisperse linear flexible polymers in both the entanglement and entanglement-free regions are analyzed quantitatively in terms of the molecular... www.alibris.com /search/books/subject/Viscoelasticity   (712 words)

Viscoelasticity of the Vessel Wall: The Role of Collagen and Elastic Fibers   (Site not responding. Last check: 2007-10-22) Analysis of the viscoelastic mechanical properties of collagen fibrils from tendon, skin, and aortic wall suggest that the collagen fibrils of aortic wall are different than those of other tissues. The elastic spring constant of the collagen fibrils in vessel walls is significantly less than that found in tendon, suggesting that the presence of type III collagen in aortic wall increases the flexibility of the collagen fibrils. Furthermore, it is hypothesized that changes in the interface between collagen fibrils, elastic fibers, and smooth muscle during aging and in connective tissue disorders leads to changes in the viscoelasticity of the vessel wall. www.edata-center.com /journals/4b27cbfc562e21b8,60a599ed4591de34,2ef3b1de0bd2597a.html   (521 words)

Viscoelasticity Solids class outline Applications of viscoelastic materials are to be examined in connection with vibration damping, relaxation of stress in fasteners, creep, droop, and sag in structural members, sound absorption, creep buckling, settlement of foundations, tire mechanics, and shock attenuation. Viscoelasticity is of use as a probe into such processes. Civil engineering: Viscoelasticity of soil and other earth materials is relevant to settlement of buildings. silver.neep.wisc.edu /~lakes/veOut.html   (321 words)

BME 332: Constitutive Equations: Viscoelasticity Although the Maxwell model did not give us a realistic result for a viscoelastic solid (it is more representative of a viscoelastic fluid) it did allow us to illustrate some important aspects of a viscoelastic material including the stress relaxation function G(t) and the creep function J(t). We can see from the mechanical analogs investigated in the previous section that the strain behavior over time of a viscoelastic material is a function of the creep function and the stress, while the stress behavior over time is a function of the stress relaxation function and the strain. Note that the form above is very similar to the linear viscoelastic model for stress, with Te the elastic response depending on the stretch ratio replacing the small strain rate. www.engin.umich.edu /class/bme456/ch7consteqviscoelasticity/bme332consteqviscoelasticity.htm   (2597 words)

Improved Clearability of Cystic Fibrosis Sputum with Dextran Treatment in vitro -- FENG et al. 157 (3): 710 -- American ... in the elevated viscoelasticity of CF sputum is attributed to in mucus viscoelasticity and a significant increase in mucociliary of rhDNase on cystic fibrosis sputum viscoelasticity in vitro. ajrccm.atsjournals.org /cgi/content/full/157/3/710   (2947 words)

Fluent - Flow Modeling Examples - Viscoelasticity Materials such as plastics, rubber, glass, biomaterials, and food are a challenge to simulate because they exhibit viscoelastic behavior, meaning that they evolve partly as a liquid and partly as a solid. A wide range of constitutive equations was implemented in Fluent CFD software to capture viscoelasticity, which include differential models, such as PTT and Giesekus, and integral models, such as KBKZ. The significant die swell is caused by viscoelastic effects. www.fluent.com /solutions/examples/x124.htm   (122 words)

MTH-3E43 : Viscoelasticity Viscoelasticity has a wide scope: both lead on roofs and glass on windows flow as very viscous liquids over large times scales but behave as solids over short time scales. Overview: The general development and broad application of the theory of viscoelasticity is of relatively recent occurrence. Even though most of the developments in viscoelasticity theory are recent the basic linear and isothermal field theory formulation has been available for a much longer time. www.mth.uea.ac.uk /maths/syllabuses/0001/3E4300.html   (644 words)

Robinson Lab Member - Kris Girard Removing myosin-II from cells causes a cytokinesis defect in suspension cultures and increases the overall cortical viscoelasticity of the cells. Dynacortin and cortexillin-I have complementary distributions during cytokinesis: cortexillin-I is enriched in the cleavage furrow, dynacortin is almost entirely excluded, and instead distributes globally around the cortex of the cell. The MSD is proportional to the cortical viscoelasticity. www.hopkinsmedicine.org /cellbio/robinson/kris.html   (253 words)

Transient Postseismic Relaxation With Burger's Body Viscoelasticity Models of a Maxwell viscoelastic interior predict a single exponential postseismic velocity relaxation. For a model composed of an elastic layer over a viscoelastic region, the coseismic changes in stress (and strain) depend only on the elastic moduli, and are independent of the description of the viscous component of the rheology. In a Burger's body model of viscoelasticity, if the viscosity of the Voigt element is much less than that of the Maxwell element, the initial relaxation time is given by the decay time $\tau = \eta_{\mathrm{Voigt}}/G_{\mathrm{Maxwell}}$. www.agu.org /cgi-bin/SFgate/SFgate?language=English&verbose=0&listenv=table&application=fm02&convert=&converthl=&refinequery=&formintern=&formextern=&transquery=hetland&_lines=&multiple=0&descriptor=%2fdata%2fepubs%2fwais%2findexes%2ffm02%2ffm02%7c645%7c4295%7cTransient%20Postseismic%20Relaxation%20With%20Burger%27s%20Body%20Viscoelasticity%7cHTML%7clocalhost:0%7c%2fdata%2fepubs%2fwais%2findexes%2ffm02%2ffm02%7c6527984%206532279%20%2fdata2%2fepubs%2fwais%2fdata%2ffm02%2ffm02.txt   (467 words)

Viscoelasticity - Wikipedia, the free encyclopedia   (Site not responding. Last check: 2007-10-22) Liquids don’t typically respond to tensile force or pulling force. Linear viscoelasticity is usually applicable only for small deformations. Nonlinear viscoelasticity is when the function is not separable. www.sciencedaily.com /encyclopedia/viscoelasticity   (314 words)

Find viscoelasticity using our Local directory   (Site not responding. Last check: 2007-10-22) For viscoelasticity our search results bring you accurate and dedicated results from across the UK and from thousands of websites offering information based on your search for viscoelasticity. Viscoelasticity and diffusional properties of colloidal model dispersions Viscoelasticity and diffusional properties of colloidal model dispersions We examine linear viscoelastic, and translational and rotational diffusion properties of... Viscoelasticity in aqueous soap gels Viscoelasticity in aqueous soap gels The viscoelastic properties of some aqueous soap gels have been measured, and explained in terms of their molecular structure. www.lifestylelocal.co.uk /search.htm?qLookingFor=viscoelasticity   (321 words)

Single-Particle Tracking: Brownian Dynamics of Viscoelastic Materials -- Qian 79 (1): 137 -- Biophysical Journal The simplest molecular theory of viscoelasticity assumes that the microscopic dynamics of a polymer network is described by In a real SPT measurement, it is important to determine whether the viscoelastic material is a solid or a liquid. Finally, note that treating macromolecules in terms of viscoelasticity is, of course, not new. www.biophysj.org /cgi/content/full/79/1/137   (3085 words)

Improved Nonlinear Mathematical Model of Viscoelasticity An improved nonlinear mathematical model is being developed for use in predicting the complex, time-varying stress-and-strain behaviors of viscoelastic materials. The development of this model is prompted by (1) the lack of success of older constitutive mathematical models that contain hereditary integrals of linear viscoelasticity (e.g., integrals that express current stresses in terms of histories of strains and of relaxation moduli) and (2) the need for a nonlinear model subject to efficient numerical implementation. Fitting this model to experimental data is expected to be much more straightforward than it is for older nonlinear mathematical models of viscoelasticity: the figure illustrates how this is so. www.nasatech.com /Briefs/Apr98/MFS28623.html   (407 words)

Understanding Viscoelasticity: Basics of Rheology specs at MSN Shopping Other books on rheology are usually comprehensive to such a degree that students find it hard to isolate the important physical principles and develop good analytical skills for solving useful engineering problems. More this book, the necessary background for understanding viscoelasticity is covered; both the continuum and microstructure approaches to modelling viscoelastic materials are discussed, since neither approach alone is sufficient. It is self-contained and ideally suited for a one-semester course on viscoelasticity. shopping.msn.com /specs/shp?itemId=1575024   (160 words)

Dr. Sally Everitt - Applied Mathematics - Recent Theses   (Site not responding. Last check: 2007-10-22) The effects of fluid viscoelasticity on the expansion of gas bubbles in polymer foams for both non-reactive and reactive polymers are investigated. The effects of viscoelasticity on the expansion of gas bubbles arranged in a two-dimensional hexagonal array in a non-reacting polymeric fluid are investigated. For the case of bubbles of two different sizes we examine the effects of viscoelasticity on the shapes of the bubbles within the structure and show that viscoelasticity has a different effect on the bubble size distribution depending upon the initial geometry. www.amsta.leeds.ac.uk /Applied/phd/everitt.html   (343 words)

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