Rheology and aging: A simple approach

Derec, Caroline; Ajdari, Armand; Lequeux, François

doi:10.1007/s101890170118

Cited by 116 publications

(115 citation statements)

References 14 publications

Supporting

Mentioning

110

Contrasting

Order By: Relevance

“…We also only study the cases when ǫ = 0 because we want to study a yield stress fluid (see [10]). The analytical study presented in our letter treats the case (α, λ, ν, ǫ) = (2, 0, 2, 0).…”

Section: Appendix: Numerical Simulations Models Comparisonmentioning

confidence: 99%

“…They are characterized by a yield stress below which the material appears as a solid [3,4]. As this behaviour is shared by so many different materials, several conceptual and theoretical frameworks emerged recently [5][6][7][8][9][10] to provide a quantitative basis for the phenomenology of soft glassy rheology (SGR) above and beyond the yield stress. Even though many parallel approaches exist, sometimes at different level of description, they all share either explicitly or implicitly, the underlying idea that mesoscopic collective processes triggered by thermal or mechanical activation, contribute to the material fluidity.…”

mentioning

confidence: 99%

“…By construction, the present fluidity model has no time scale. When imposing a modulation, one can study the in-phase and out-of-phase responses [10] over a time of the order of τ vib = 2π…”

mentioning

confidence: 99%

See 2 more Smart Citations

Mechanical fluctuations suppress the threshold of soft-glassy solids: The secular drift scenario

et al. 2015

View full text Add to dashboard Cite

We propose a dynamical mechanism leading to the fluidization by external mechanical fluctuations of soft-glassy amorphous material driven below the yield-stress. The model is based on the combination of memory effect and non-linearity, leading to an accumulation of tiny effects over a long-term. We test this scenario on a granular packing driven mechanically below the Coulomb threshold. We bring evidences for an effective viscous response directly related to small stress modulations in agreement with the theoretical prediction of a generic secular drift. We finally propose to extend this result more generally, to a large class of glassy systems.PACS numbers: 81.40. Lm, 83.80.Fg Numerous amorphous materials such as concentrated suspensions, colloidal glasses, foams or granular materials share common global features in their mechanical response to shear [1,2]. They are characterized by a yield stress below which the material appears as a solid [3,4]. As this behaviour is shared by so many different materials, several conceptual and theoretical frameworks emerged recently [5][6][7][8][9][10] to provide a quantitative basis for the phenomenology of soft glassy rheology (SGR) above and beyond the yield stress. Even though many parallel approaches exist, sometimes at different level of description, they all share either explicitly or implicitly, the underlying idea that mesoscopic collective processes triggered by thermal or mechanical activation, contribute to the material fluidity. The direct visualization of local plastic events and the associated complex avalanching dynamics is supported by many experimental [11][12][13][14] or numerical [15][16][17] studies. In the "solid phase" corresponding to a strong dynamical arrest, soft-glassy systems display ageing properties manifesting in a slow creep relaxation process [18][19][20][21]. Ageing properties stem from a remaining thermal activation providing the possibility to cross enthalpic or entropic barriers and progressively set the system into deeper local minima where mechanical solidity is reinforced. The existence of external mechanical noise was also proposed as a substitute for thermal activation. In this sense, the behaviour of these amorphous soft glassy solids is very close phenomenologically to molecular glass-formers obtained by thermal quenching [22]. Yet, the fact that such mechanical noise truly acts as an effective temperature is presently debated [23] and indeed, deep differences in the way thermal noise and mechanical fluctuations act in amorphous systems has been recently pointed out [24].

show abstract

Section: Appendix: Numerical Simulations Models Comparisonmentioning

confidence: 99%

mentioning

confidence: 99%

See 1 more Smart Citation

Mechanical fluctuations suppress the threshold of soft-glassy solids: The secular drift scenario

et al. 2015

View full text Add to dashboard Cite

show abstract

“…A second unexpected finding is that a low dimensional truncation of our model also gives chaos, even though sharp interfaces between shear bands are then suppressed. Thus high-order Fourier components of spatial variation are not essential to rheochaos.Candidates for a slow structural mode include the mean length of wormlike micelles, local composition variables (e.g., colloidal volume fraction) and 'fluidity' parameters [18,19] reflecting local microstructure, bonding state, etc.. In all cases, the time scale τ S is distinct from the Maxwell time τ M for linear stress relaxation; and in our work, we assume τ S /τ M ≥ 1 (in contrast to [16]).…”

mentioning

confidence: 99%

Instability and spatiotemporal rheochaos in a shear-thickening fluid model

Aradian¹,

Cates²

2005

Europhys. Lett.

View full text Add to dashboard Cite

We model a shear-thickening fluid that combines a tendency to form inhomogeneous, shear-banded flows with a slow relaxational dynamics for fluid microstructure. The interplay between these factors gives rich dynamics, with periodic regimes (oscillating bands, travelling bands, and more complex oscillations) and spatiotemporal rheochaos. These phenomena, arising from constitutive nonlinearity not inertia, can occur even when the steady-state flow curve is monotonic. Our model also shows rheochaos in a low-dimensional truncation where sharply defined shear bands cannot form.Complex fluids exhibit much interesting behavior under shear, due to strong couplings between mesoscopic structure and flow. Experiments show cases where, under steady external driving, an unstable flow arises, giving a time-dependent strain rate at constant imposed shear stress, or vice versa. Sustained temporal oscillations are seen in surfactant mesophases and solutions [1,2,3,4,5,6] and polymer solutions [7], while erratic temporal responses have been found both in these and in related materials, e.g., wormlike micelles [8,9,10], lamellar phases [4,5,11] and colloids [12,13]. There are strong indications [4,8,9] that these erratic signals result from a deterministic chaotic dynamics. Chaotic behavior of bulk flows at virtually zero Reynolds number (negligible inertia) must stem from nonlinearity within the rheological constitutive equation, and has been dubbed 'rheochaos ' [14, 15, 16].Such flow instabilities affect both shear-thinning [8] and shear-thickening micellar materials [9]. Shear-thickening is, in itself, a widely observed but poorly understood phenomenon which affects not only micelles but, e.g., dense colloids, where there is again evidence of bulk rheological instability [12,13]. Below we study a simple model for a shear-thickening fluid at steady controlled stress, which generalises to spatially inhomogeneous flows a model first proposed in Ref. [14]. The latter was shown to give simple oscillations but not chaos (unless an unconvincing 'double memory' term was used). We find that the interplay of a very simple structural memory with constitutive nonlinearity can, as hoped by the authors of [14], give complex dynamics and rheochaos -but only if spatial heterogeneity is allowed for. Our work is related to, but different from, that of Fielding and Olmsted [16] which addresses shear-thinning fluids [17]. Also related is Ref.[15] which concerns nematic liquid crystals (which can be chaotic even without spatial heterogeneity). We show below that there are robust generic features in the rheochaos produced in these various models, which generally involve a failed attempt to create a steady shearbanded flow. (In the shear thinning case the bands have a common stress but unequal strain rates; for us, the reverse is true.) One distinctive finding of our work is rheochaos in a model where the steady state flow curve is strictly monotonic. Here (in contrast with [16]) no steady banded solution, stable or otherwise, exists. Yet an innate t...

show abstract

“…Fortunately, a recent experiment [26,27] turns out to be helpful here. Ironically, its authors employ sand as a model for amorphous glassy materials (say dense colloidal suspensions), and compare their observation to a theory on them [38]. Calling the rate by which the shear stress relaxes fluidity f , the theory postulates an f that also relaxes (aging), and is increased by a shear flow (rejuvenation).…”

Section: Stress-controlled Rheologymentioning

confidence: 99%

Stress- and rate-controlled granular rheology

Jiang

Liu

2013

AIP Conference Proceedings

View full text Add to dashboard Cite

Abstract. Granular solid hydrodynamics (GSH) is employed to account for granular rheology, both the rate-controlled one, smoothly extending from the critical state to the Bagnold regime, and the stress-controlled one that is discontinuous and hysteretic. Employing GSH, it is shown that a quiescent state is stable below the smaller jamming stress and instable above the larger fluidization stress, with values in between being metastable; also, that the MiDi relation, appropriate for rigid grains, needs to be rectified, because real granular media, with a sound velocity one to three times that of air, are soft.

show abstract

Rheology and aging: A simple approach

Cited by 116 publications

References 14 publications

Mechanical fluctuations suppress the threshold of soft-glassy solids: The secular drift scenario

Mechanical fluctuations suppress the threshold of soft-glassy solids: The secular drift scenario

Instability and spatiotemporal rheochaos in a shear-thickening fluid model

Stress- and rate-controlled granular rheology

Contact Info

Product

Resources

About