A geometrical interpretation of large amplitude oscillatory shear response

Cho, Kwang Soo; Hyun, Kyu; Ahn, Kyung Hyun; Lee, Seung Jong

doi:10.1122/1.1895801

Cited by 372 publications

(205 citation statements)

References 16 publications

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“…The third plot shown in figure 9 (c) is a Lissajous curve of the bulk stress-strain response of the fluid to the oscillatory deformation (averaged over five periods of oscillation). The data is analyzed using the MITlaos software package (Ewoldt et al, 2008) in order to extract the decomposed elastic stress (Cho et al, 2005;Ewoldt et al, 2008) as well as the higher order Fourier/Chebyschev coefficients that describe the periodic stress response. Ewoldt et al (2008) showed how the higher order Fourier coefficients can be directly related to more physically meaningful elastic Chebyshev In (a), the evolution of the local velocity field is shown over one half of a period with 15 velocity profiles evenly spaced every 0.33 seconds.…”

Section: The Linear Viscoelastic Regime -Saosmentioning

confidence: 99%

“…Large amplitude oscillatory shear (LAOS) is used to progressively deform the material deeper into the nonlinear regime and probe the onset of shear-banding behavior in the absence of substantial secondary flows and wall slip. We also use the LAOS framework developed in previous work (Cho et al, 2005;Ewoldt et al, 2008Ewoldt et al, , 2010 to connect local kinematic measurements with nonlinearities in the bulk rheology, and show that the onset of shear banded velocity profiles closely coincides with the growth of nonlinearities in the bulk viscoelastic response. Similar behavior has recently been explored using some of the microstructural constitutive models that have been proposed for describing the rheology of shear banding systems (Adams and Olmsted, 2009;Zhou et al, 2010), providing an opportunity in the future for comparing experimental data with theoretical predictions.…”

Section: Introductionmentioning

confidence: 99%

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Rheo-PIV of a shear-banding wormlike micellar solution under large amplitude oscillatory shear

et al. 2012

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We explore the behavior of a wormlike micellar solution under both steady and large amplitude oscillatory shear (LAOS) in a cone-plate geometry through simultaneous bulk rheometry and localized velocimetric measurements. First, particle image velocimetry is used to show that the shear banded profiles observed in steady shear are in qualitative agreement with previous results for flow in the cone-plate geometry. Then under LAOS, we observe the onset of shear-banded flow in the fluid as it is progressively deformed into the non-linear regime -this onset closely coincides with the appearance of higher harmonics in the periodic stress signal measured by the rheometer. These harmonics are quantified using the higher order elastic and viscous Chebyshev coefficients e n and v n , which are shown to grow as the banding behavior becomes more pronounced. The high resolution of the velocimetric imaging system enables spatiotemporal variations in the structure of the banded flow to be observed in great detail. Specifically, we observe that at large strain amplitudes (γ 0 ≥ 1) the fluid exhibits a 3-banded velocity profile with a high shear rate band located in-between two lower shear rate bands adjacent to each wall. This band persists over the full cycle of the oscillation, resulting in no phase lag being observed between the appearance of the band and the driving strain amplitude. In addition to the kinematic measurements of shear banding, the methods used to prevent wall slip and edge irregularities are discussed in detail, and these methods are shown to have a measurable effect on the stability boundaries of the shear banded flow.

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Section: The Linear Viscoelastic Regime -Saosmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Rheo-PIV of a shear-banding wormlike micellar solution under large amplitude oscillatory shear

et al. 2012

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“…In the case of LAOS, a 0 =0, and provided there is not and slip between the apparatus and the material, a 2k =b 2k =0 for any k (both of these facts are due to the fact that the system is symmetric across the midpoint of the oscillation without slip) [50,51]. Additionally, the in phase components b n , n odd, are similar to the storage and the out of phase components a n , n odd, play a similar role to the loss.…”

Section: Introductionmentioning

confidence: 99%

“…shear and stress in LAOS, or temperature and energy in dynamic heat capacity) are plotted against each other [50,51]. The degree of nonlinearity is easily shown by such plots because, if the system were linear, these plots would be ellipses, and nonlinear behavior shows up as deformities in these elliptical shapes.…”

Section: Introductionmentioning

confidence: 99%

“…For example, suddenly dropping the temperature of a system by a large amount causes a slower relaxation than suddenly raising it [49] (see Fig 13). In the frequency domain, the most common application for nonlinear studies is large amplitude oscillatory shear (LAOS) experiments [50,51]. In short, a piece of material in question is placed under a sinusoidal shear strain with variable amplitude and frequency; as the amplitude of the strain is increased, the assumptions of linear response theory no longer hold.…”

Section: Introductionmentioning

confidence: 99%

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Dynamic heat capacity of the east model and of a bead-spring polymer model.

Adolf¹

2011

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In this report we have presented a brief review of the glass transition and one means of characterizing glassy materials: linear and nonlinear thermodynamic oscillatory experiments to extract the dynamic heat capacity. We have applied these methods to the east model (a variation of the Ising model for glass forming systems) and a simple polymeric system via molecular dynamics simulation, and our results match what is seen in experiment. For the east model, since the dynamics are so simple, a mathematical model is developed that matches the simulated dynamics. For the polymeric system, since the system is a simulation, we can instantaneously "quench" the system -removing all vibrational energy -to separate the vibrational dynamics from dynamics associated with particle rearrangements. This shows that the long-time glassy dynamics are due entirely to the particle rearrangements, i.e. basin jumping on the potential energy landscape. Finally, we present an extension of linear dynamic heat capacity to the nonlinear regime.

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Rheology and Rheological Measurements

Ahmed

2021

Kirk-Othmer Encyclopedia of Chemical Technology

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This article presents the experimental measurement of the rheological properties of both liquids and solids and the principles on which these measurements are based. The flow properties of a liquid are defined by its resistance to flow, that is, viscosity. This concept is defined and discussed in terms of both theoretical flow models and practical consequences. Temperature, thixotropic and other time‐dependent, and concentration effects are covered for dilute polymer solutions, melts, and dispersed systems. Techniques and viscometers for capillary, rotational, and moving‐body measurements are described. The rheological properties of viscoelastic solids are made up of a combination of permanent deformation and recoverable elastic deformation. Additionally, a number of liquids show elastic and flow behaviors, which are commonly termed as the viscoelastic materials. Some additional techniques have been included beyond those indicated for simple solids and liquids, which are needed for a complete characterization of the mechanical behavior of materials in terms of elasticity and viscoelasticity. Examples of such methods are the dynamic measurement of response to sinusoidal oscillatory motion; the measurement of flow with time after application of stress, that is, creep; and the measurement of the rate and degree of recovery after removal of stress, that is, creep recovery or recoil. A few special topics, including the Weissenberg effect, time–temperature superposition principles (TTSP), and electrorheological measurements, are also discussed. Nonlinear dynamic measurements of the complex fluids in terms of the large amplitude oscillatory shear (LAOS) measurements, including the Fourier transform rheology and Lissajous curves, are discussed.

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A geometrical interpretation of large amplitude oscillatory shear response

Cited by 372 publications

References 16 publications

Rheo-PIV of a shear-banding wormlike micellar solution under large amplitude oscillatory shear

Rheo-PIV of a shear-banding wormlike micellar solution under large amplitude oscillatory shear

Dynamic heat capacity of the east model and of a bead-spring polymer model.

Rheology and Rheological Measurements

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