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Steady state shear response

Phase Transitions and the Steady State Shear Response... [Pg.96]

Steady state acoustic response of the unit cell occurred for the composites considered after the passage of some five acoustic oscillations. Patterns of direct stress, and shear stress as shown in Figures 2 and 3 were obtained. As expected, the corners of the cavities concentrated the stresses. Viscoelastic energy loss calculations, not discussed here, also show that the corners of the cavities are concentrations of energy losses. [Pg.269]

The viscosity of a macromolecular solution can undergo changes when subjected to a periodic shear wave of frequency, w, instead of a steady-state shearing stress. The response of the particles to such a sinusoidally oscillating shear can be expressed in terms of a complex viscosity, rt -. [Pg.373]

Steady-state shear rheology typically involves characterizing the polymer s response to steady shearing flows in terms of the steady shear viscosity (tj), which is defined by the ratio of shear stress (a) to shearing rate y ). The steady shear viscosity is thus a measure of resistance to steady shearing deformation. Other characteristics such as normal stresses (Ai and N2) and yield stresses (ffy) are discussed in further detail in Chapter 3. [Pg.170]

The theory has only a single adjustable parameter, which corresponds to the Rouse time (the characteristic relaxation time for an unconfined chain) of the polymer, and it does a quite reasonable job of predicting the hnear viscoelastic response and the transient and steady-state shear and normal stresses in simple shear, ft is not as good as more complex tube-based models hke the pom-pom model, and it cannot be used for nonviscometric flows because of the absence of a continuum representation, but it contains structural details and is very useful for providing insight into the mechanics of slip. [Pg.205]

Such data has similarities with earlier studies on lyotropic aqueous solutions of HPC (15,16). The equivalent orientational behaviour in steady state shear flow for a 55% w/v aqueous HPC solution is shown in Figure 12. These data also show three regimes although the level of preferred orientation at low shear rates is clearly greater for the aqueous solution, and the distinction between regimes 2 3 are blurred. Lyotropic HPC and thermotropic PPC have considerably different concentrations of liquid crystal forming molecule (55% and 100%), yet their responses to the flow field are similar. It is emphasized that we can make direct comparisons between these two materials since the derivative PPC and the lyotropic solutions were prepared from the polymer Klucel E which was used to prepare the aqueous solutions. [Pg.400]

Contractive then dilative (tendency) response is commonly encountered in xmdrained laboratory testing of sandy soils. This response is similar to contractive undrained response, except that upon reaching a minimum shear resistance, the sand strain-hardens. Alarcon-Guzman et al. (1988) termed this minimum shear resistance the quasi-steady state shear strength based on steady state flow concepts (Poulos 1981) thus, the term quasi-critical state shear strength also... [Pg.2178]

B2 = contractive then dilative response where minimum shear resistance is maintained over range of shear strain less than 3 %, s (ss) = steady state shear strength, which is equivalent to critical state shear strength (Modified from Olson and Mattson 2008 with permission from Canadian Science Publishing)... [Pg.2187]

Figure 6.15 The responses cr(y) and N (y) to shear rate y as an input variable in steady-state shear flow, and the responses G (o)) and G"(a>) to small-amplitude sinusoidal strain y (ia>) with an angular frequency as an input variable in oscillatory shear flow. Figure 6.15 The responses cr(y) and N (y) to shear rate y as an input variable in steady-state shear flow, and the responses G (o)) and G"(a>) to small-amplitude sinusoidal strain y (ia>) with an angular frequency as an input variable in oscillatory shear flow.
Here, we present the transient and steady-state rheological responses after resting upon cessation of initial shear flow (referred to as intermittent shear flow). [Pg.426]

Dyna.mic Viscometer. A dynamic viscometer is a special type of rotational viscometer used for characterising viscoelastic fluids. It measures elastic as weU as viscous behavior by determining the response to both steady-state and oscillatory shear. The geometry may be cone—plate, parallel plates, or concentric cylinders parallel plates have several advantages, as noted above. [Pg.187]

Typical for the spectroscopic character of the measurement is the rapid development of a quasi-steady state stress. In the actual experiment, the sample is at rest (equilibrated) until, at t = 0, oscillatory shear flow is started. The shear stress response may be calculated with the general equation of linear viscoelasticity [10] (introducing Eqs. 4-3 and 4-9 into Eq. 3-2)... [Pg.209]

An important and sometimes overlooked feature of all linear viscoelastic liquids that follow a Maxwell response is that they exhibit anti-thixo-tropic behaviour. That is if a constant shear rate is applied to a material that behaves as a Maxwell model the viscosity increases with time up to a constant value. We have seen in the previous examples that as the shear rate is applied the stress progressively increases to a maximum value. The approach we should adopt is to use the Boltzmann Superposition Principle. Initially we apply a continuous shear rate until a steady state... [Pg.125]

It turns out that stress relaxation following a simple shear deformation is seldom employed experimentally. A more common technique is to measure the steady state response to small sinusoidal deformations as a function of angular frequency to. The dynamic storage modulus G (to) and loss modulus G"(to) in small sinusoidal deformations are related to G(t) ... [Pg.22]

If the response of a sample to a change in shear is reversible and essentially instantaneous within the time frame of the measurement, it is said to be time independent. Most shear-thinning or shear-thickening materials are time independent. Alternatively, the sample can take seconds, minutes, hours, or longer to reach steady state such materials are said to be time dependent. This delayed response to a change in applied shear can have a significant impact on processing considerations. [Pg.1138]


See other pages where Steady state shear response is mentioned: [Pg.210]    [Pg.11]    [Pg.36]    [Pg.481]    [Pg.8]    [Pg.502]    [Pg.502]    [Pg.505]    [Pg.747]    [Pg.669]    [Pg.679]    [Pg.816]    [Pg.822]    [Pg.846]    [Pg.37]    [Pg.171]    [Pg.177]    [Pg.164]    [Pg.391]    [Pg.128]    [Pg.2178]    [Pg.218]    [Pg.378]    [Pg.248]    [Pg.166]    [Pg.184]    [Pg.414]    [Pg.225]    [Pg.238]    [Pg.261]    [Pg.272]    [Pg.60]    [Pg.1138]   
See also in sourсe #XX -- [ Pg.96 , Pg.97 , Pg.98 , Pg.99 , Pg.100 ]




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