Rheological Behavior of Semisolid Al-6.5wt%Si Alloy at Transient State

2011 ◽  
Vol 306-307 ◽  
pp. 100-103
Author(s):  
Hong Chao Luo ◽  
Wei Wang ◽  
En Sheng Xu ◽  
Li Ping Ju
Keyword(s):  
Rheological Behavior ◽  
Experimental Measurement ◽  
Rheological Model ◽  
Shear Thickening ◽  
Transient State ◽  
Shear Thinning ◽  
Agglomerate Size ◽  
Resting Time ◽  
Semisolid Metal

In the present work, the rheological model for semisolid metal slurries (SSMS) is constructed and then applied to the Al-6.5wt%Si alloy to investigate its rheological behavior at transient state during isothermal shearing and isothermal resting. Firstly, the present study shows that the agreement of the variation of viscosity and the average agglomerate size with shearing time and resting time shows that the microstructure of SSMS determines its rheological behavior. Secondly, the deagglomeration of particles is about two orders of magnitude faster than agglomeration, which is in agreement with the experimental measurement. Finally, the Al-6.5wt%Si alloy at transient state has the behavior of “shear-thinning”, but not “shear-thickening” predicted in the documents.

Rheological Behavior of Semisolid AlSi6Mg2 Alloy at Transient State

2012 ◽  
Vol 217-219 ◽  
pp. 369-372
Author(s):  
Li Ping Ju ◽  
Ying Wu ◽  
En Sheng Xu ◽  
Wei Wang ◽  
Hong Chao Luo
Keyword(s):  
Shear Rate ◽  
Rheological Behavior ◽  
Rheological Model ◽  
Transient State ◽  
External Flow ◽  
Flow Conditions ◽  
Agglomerate Size ◽  
Resting Time

In the present work, basing on the rheological model of Chen and Fan [1], the rheological behavior of AlSi6Mg2 alloy at transient state is investigated. It has been shown that the deagglomeration of particles is about two orders of magnitude faster than the agglomeration of them. The inequality of agglomeration rate and deagglomeration rate is thought as the origin of the thixotropy of SSMS. Subsequently, the similar trend of the variation of the viscosity and the average agglomerate size with shearing time and resting time shows that the microstructure of SSMS determines its rheological behavior, while the external flow conditions (such as shear rate, shearing time, etc) influence the viscosity by changing its microstructure. The present study predicts that the CF model can describe reliably the transient rheological behavior of AlSi6Mg2 alloy.

scholarly journals Influence of Nano-SiO2, Nano-CaCO3 and Nano-Al2O3 on Rheological Properties of Cement–Fly Ash Paste

Materials ◽  
2019 ◽  
Vol 12 (16) ◽  
pp. 2598 ◽  
Author(s):  
Yiming Peng ◽  
Kunlin Ma ◽  
Guangcheng Long ◽  
Youjun Xie
Keyword(s):  
Fly Ash ◽  
Rheological Properties ◽  
Yield Stress ◽  
Free Water ◽  
Shear Thickening ◽  
Shear Thinning ◽  
Plastic Viscosity ◽  
Behavior Changes ◽  
Nano Sio2 ◽  
Resting Time

Rheological curves of cement–fly ash (C–FA) paste incorporating nanomaterials including nano-SiO2 (NS), nano-CaCO3 (NC) and nano-Al2O3 (NA) at different resting times (hydration time of 5 min, 60 min, and 120 min) were tested with a rheometer. The rheological behaviors were described by the Herschel–Bulkley (H–B) model, and the influences of these nanomaterials on rheological properties of C–FA paste were compared. Results show that the types, content of nanomaterials and resting time have great influences on the rheological properties of C–FA paste. Incorporating NS and NA increases yield stress and plastic viscosity, and decreases the rheological index of C–FA paste. When the content of NS and NA were 2 wt%, the rheological index of C–FA paste was less than 1, indicating rheological behavior changes from shear thickening to shear thinning. Meanwhile, with rising resting time, yield stress and plastic viscosity increased significantly, but the rheological index decreased evidently, showing paste takes on shear thinning due to the rise of resting time. However, incorporating 3 wt% NC and the rising of resting time did not change the rheological properties of C–FA paste. These differences are mainly that the specific surface area (SSA) of NS (150 m2/g) and NA (120 m2/g) are much larger than that of NC (40 m2/g). The huge SSA of NS and NA consume lots of free water and these tiny particles accelerate the hydration process during resting time.

Stability of Shear-Thickening Liquids Between Rotating Cylinders

2010 ◽  
Author(s):  
Nariman Ashrafi ◽  
Habib Karimi Haghighi
Keyword(s):  
Couette Flow ◽  
Dynamical Behavior ◽  
Shear Thickening ◽  
Shear Thinning ◽  
Taylor Vortex ◽  
Shear Dependent Viscosity ◽  
Shear Thinning Fluids ◽  
Shear Thickening Fluids ◽  
The Stability ◽  
Dependent Viscosity

The effects of nonlinearities on the stability are explored for shear thickening fluids in the narrow-gap limit of the Taylor-Couette flow. It is assumed that shear-thickening fluids behave exactly as opposite of shear thinning ones. A dynamical system is obtained from the conservation of mass and momentum equations which include nonlinear terms in velocity components due to the shear-dependent viscosity. It is found that the critical Taylor number, corresponding to the loss of stability of Couette flow becomes higher as the shear-thickening effects increases. Similar to the shear thinning case, the Taylor vortex structure emerges in the shear thickening flow, however they quickly disappear thus bringing the flow back to the purely azimuthal flow. Naturally, one expects shear thickening fluids to result in inverse dynamical behavior of shear thinning fluids. This study proves that this is not the case for every point on the bifurcation diagram.

Investigation on the Rheological Behavior of Polyamide6/Montmorillonite Nanocomposites by Reactive Extrusion

2011 ◽  
Vol 233-235 ◽  
pp. 1998-2001 ◽  
Author(s):  
Ming Zhao ◽  
Xiao Zhong Lu ◽  
Kai Gu ◽  
Xiao Min Sun ◽  
Chang Qing Ji
Keyword(s):  
Activation Energy ◽  
Shear Stress ◽  
Shear Rate ◽  
Rheological Behavior ◽  
Reactive Extrusion ◽  
Shear Thinning ◽  
Experimental Results ◽  
Montmorillonite Nanocomposites

The rheological behavior of PA6/montmorillonite(MMT) by reactive extrusion was investigated using cone-and-plate rheometer. The experimental results indicated that PA6/MMT exhibited shear-thinning behavior. The shear stress of both neat PA6 and PA6/MMT increased with the increase in the shear rate. The reduction of the viscous activation energy with the increase of shear stress reflected PA6/MMT can be processed over a wider temperature.

scholarly journals The Effect of Rheology of Viscoelastic Polymer on Pressure Transient Response in Near-Wellbore Regions

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Jia Zhang ◽  
Shiqing Cheng ◽  
Jie Zhan ◽  
Qi Han
Keyword(s):  
Shear Thickening ◽  
Shear Thinning ◽  
Polymer Flooding ◽  
High Shear ◽  
Pressure Data ◽  
Transient Pressure ◽  
Pressure Derivative ◽  
Shear Rates ◽  
Viscoelastic Polymer ◽  
Thickening Behavior

Viscoelastic polymer solution shows shear thinning behavior at low shear rates and shear thickening behavior at high shear rates in reservoirs. However, models that ignored shear thickening behavior were commonly employed to interpret transient pressure data derived from tested wells in viscoelastic polymer flooding systems; although, viscoelastic polymer solutions show shear thickening behavior in the near-wellbore region due to high shear rate. To better characterize the oilfield with pressure transient analysis in viscoelastic polymer flooding systems, we developed a numerical model that takes into account both shear thinning behavior and shear thickening behavior. A finite volume method was employed to discretize partially differential flow equations in a hybrid grid system including PEBI mesh and Cartesian grid, and the Newton-Raphson method was used to solve the fully implicit nonlinear system. To illustrate the significance of our model, we compared our model with a model that ignores the shear thickening behavior by graphing their solutions on log-log plots. In the flow regime of near-wellbore damage, the pressure derivative computed by our model is distinctly larger than that computed by the model ignoring shear thickening behavior. Furthermore, the effect of shear thickening behavior on pressure derivative differs from that of near-wellbore damage. We then investigated the influence of shear thickening behavior on pressure derivative with different polymer injection rates, injection rates, and permeabilities. The results can provide a benchmark to better estimate near-wellbore damage in viscoelastic polymer flooding systems. Besides, we demonstrated the applicability and accuracy of our model by interpreting transient pressure data from a field case in an oilfield with viscoelastic polymer flooding treatments.

Phase segregation, shear thinning and rheological behavior of crude oil-in-water emulsions

2014 ◽  
Vol 92 (9) ◽  
pp. 1629-1636 ◽  
Author(s):  
Ronaldo Gonçalves dos Santos ◽  
Antonio Carlos Bannwart ◽  
Watson Loh
Keyword(s):  
Crude Oil ◽  
Rheological Behavior ◽  
Phase Segregation ◽  
Shear Thinning ◽  
Oil In Water

The Effect of the Microstructure of Semisolid Al Alloy on its Rheology

2014 ◽  
Vol 490-491 ◽  
pp. 109-112
Author(s):  
De Wen Cao ◽  
Jia Huan Wang ◽  
Yu Qing Sun ◽  
Ke Hua Chen ◽  
Cheng Ming Yu ◽  
...  
Keyword(s):  
Particle Size ◽  
Rheological Behavior ◽  
Volume Fraction ◽  
Solid Volume Fraction ◽  
Alloy System ◽  
The State ◽  
Solid Particles ◽  
Al Alloy ◽  
Agglomerate Size ◽  
The One

In the present work, the effect of the microstructure of AlSi6Mg2 alloy on its macro-rheological behavior of the steady AlSi6Mg2 alloy is investigated. Specifically, the effect of particle size, packing mode and degree of the agglomeration of particles are analyzed. It can be seen that the apparent viscosity decreases with increasing the particle size (d) ifdis between a few μm and 200 μm, while the solid particle size does not affect viscosity except this region. This theoretical prediction is in qualitatively agreement with the experimental data. The trend of the variation of the average agglomerate size with the particle size is the same as the one of viscosity. The packing mode of solid particles in agglomerate is closely related to the solid volume fraction and the characteristics of the alloy system. Subsequently, the state of agglomeration of solid particles which determines the rheology of semisolid AlSi6Mg2 alloy, while the external flow conditions (such as shear rate) influence the viscosity by changing the state of agglomeration. Consequently, the particle size, the packing mode and the average agglomerate size have different effect on the rheological behavior of SSMS.

A facile one-step method to synthesize SiO2@polydopamine core–shell nanospheres for shear thickening fluid

RSC Advances ◽  
2016 ◽  
Vol 6 (35) ◽  
pp. 29279-29287 ◽  
Author(s):  
Mei Liu ◽  
Wanquan Jiang ◽  
Qian Chen ◽  
Sheng Wang ◽  
Ya Mao ◽  
...  
Keyword(s):  
Rheological Behavior ◽  
Shear Thickening ◽  
Core Shell ◽  
Step Method ◽  
Shear Thickening Fluid ◽  
One Step

An illustration of the synthesis of SiO2@PDA core/shell nanospheres, in which the coating on the surface of the SiO2nanospheres improves the rheological behavior of the resulting STFs.

Dynamic wetting failure in shear-thinning and shear-thickening liquids

2020 ◽  
Vol 892 ◽  
Author(s):  
Vasileios Charitatos ◽  
Wieslaw J. Suszynski ◽  
Marcio S. Carvalho ◽  
Satish Kumar
Keyword(s):  
Shear Thickening ◽  
Shear Thinning ◽  
Dynamic Wetting ◽  
Image Position

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