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.

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.

The Steady State Rheological Behavior of Semisolid AlSi6Mg2 Alloy

2011 ◽  
Vol 339 ◽  
pp. 257-260 ◽  
Author(s):  
Hong Chao Luo ◽  
Shi Pu Chen ◽  
Qin Nie ◽  
En Sheng Xu ◽  
Li Ping Ju
Keyword(s):  
Steady State ◽  
Shear Rate ◽  
Rheological Behavior ◽  
Volume Fraction ◽  
Solid Volume Fraction ◽  
Solid Particles ◽  
Experimental Results ◽  
Present System ◽  
Flow Conditions ◽  
Good Agreement

In the present work, basing on the rheological model of Chen and Fan (CF) [1] of semisolid metal slurries (SSMS), the rheological behavior at steady state of AlSi6Mg2 alloy is investigated. Experimental results on steady state viscosity of the present system in the literature are used to determine the parameters of the CF model by fitting. It has been shown that the steady state viscosity and the average agglomerate size increase with increasing the solid volume fraction and decreasing the shear rate. The theoretical prediction of the CF model is in good agreement with the experimental results in the literatures quantitatively. The importance of the effective solid volume fraction is shown by explaining the strong coupling between the viscosity and the microstructure. Specifically, the external flow conditions such as shear rate influences the viscosity by changing the agglomeration degree of the solid particles, that is, the effective solid volume fraction and then changing the viscosity.

A Rheological Model of Semisolid Magnesium Alloy Slurries

2005 ◽  
Vol 488-489 ◽  
pp. 333-336 ◽  
Author(s):  
L. Li ◽  
X.W. Zhou ◽  
J.Y. Chen
Keyword(s):  
Magnesium Alloy ◽  
Shear Rate ◽  
Rheological Properties ◽  
Apparent Viscosity ◽  
Rheological Model ◽  
The State ◽  
Simple Shearing ◽  
Flow Conditions ◽  
Rheological Behaviors ◽  
Microstructure Model

In this paper a rheological model is presented which describes the rheological behaviors of liquid-like semisolid magnesium alloy under a simple shearing flow. On the basis of Chen and Fan’s mono-dispersion microstructure model of semisolid metal slurry, the particle size distribution is considered in this model. It is believed that it is the state of agglomeration which determines the rheological behaviors of the slurry, whereas the external flow conditions such as shear rate and shearing time, affect the rheological properties by changing the state of agglomeration. The expressions of collision rate between two agglomerates, effective solid fraction and the formula of apparent viscosity of Chen and Fan’s model are corrected according to the experimental results and statistical mechanics. Finally calculated apparent viscosity and the average number of the particles of AZ91D by the developed model as functions of shear rate are presented. These results show that there is a one to one coupling between the rheological properties of the magnesium alloy slurries and the state of the agglomeration.

Platelet and Shear Rate Promote Tumor Cell Adhesion to Human Endothelial Extracellular Matrix - Absence of a Role for Platelet Cyclooxygenase

1989 ◽  
Vol 61 (03) ◽  
pp. 485-489 ◽  
Author(s):  
Eva Bastida ◽  
Lourdes Almirall ◽  
Antonio Ordinas
Keyword(s):  
Cell Adhesion ◽  
Shear Rate ◽  
Tumor Cell ◽  
Umbilical Vein ◽  
Blood Platelets ◽  
Flow Conditions ◽  
Tumor Cell Adhesion ◽  
Rate Dependent ◽  
Static Conditions

SummaryBlood platelets are thought to be involved in certain aspects of malignant dissemination. To study the role of platelets in tumor cell adherence to vascular endothelium we performed studies under static and flow conditions, measuring tumor cell adhesion in the absence or presence of platelets. We used highly metastatic human adenocarcinoma cells of the lung, cultured human umbilical vein endothelial cells (ECs) and extracellular matrices (ECM) prepared from confluent EC monolayers. Our results indicated that under static conditions platelets do not significantly increase tumor cell adhesion to either intact ECs or to exposed ECM. Conversely, the studies performed under flow conditions using the flat chamber perfusion system indicated that the presence of 2 × 105 pl/μl in the perfusate significantly increased the number of tumor cells adhered to ECM, and that this effect was shear rate dependent. The maximal values of tumor cell adhesion were obtained, in presence of platelets, at a shear rate of 1,300 sec-1. Furthermore, our results with ASA-treated platelets suggest that the role of platelets in enhancing tumor cell adhesion to ECM is independent of the activation of the platelet cyclooxygenase pathway.

Modeling of Shear Rheological Behavior of Uncured Rubber Melt

2020 ◽  
Vol 30 (1) ◽  
pp. 130-137
Author(s):  
Hengxiao Yang ◽  
Qimian Mo ◽  
Hengyu Lu ◽  
Shixun Zhang ◽  
Wei Cao ◽  
...  
Keyword(s):  
Shear Rate ◽  
Constitutive Model ◽  
Incompressible Fluid ◽  
Rheological Behavior ◽  
Rheological Characteristics ◽  
One Dimensional ◽  
Ptt Model ◽  
Rate Region ◽  
Proposed Model ◽  
Rheological Experiments

AbstractTo describe uncured rubber melt flow, a modified Phan–Thien–Tanner (PTT) model was proposed to characterize the rheological behavior and a viscoelastic one-dimensional flow theory was established in terms of incompressible fluid. The corresponding numerical method was constructed to determine the solution. Rotational rheological experiments were conducted to validate the proposed model. The influence of the parameters in the constitutive model was investigated by comparing the calculated and experimental viscosity to determine the most suitable parameters. The uncured rubber viscosity was 3–4 orders larger than that of plastic and did not have a visible Newtonian region. Compared with the Cross-Williams-Landel-Ferry (Cross-WLF) and original PTT models, the modified PTT model can describe the rheological characteristics in the entire shear-rate region if the parameters are set correctly.

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.

Rheological behavior of an artificial synovial fluid – influence of temperature, shear rate and pressure

2021 ◽  
Vol 115 ◽  
pp. 104278
Author(s):  
Benedict Rothammer ◽  
Max Marian ◽  
Florian Rummel ◽  
Stefan Schroeder ◽  
Maximilian Uhler ◽  
...  
Keyword(s):  
Shear Rate ◽  
Synovial Fluid ◽  
Rheological Behavior ◽  
Influence Of Temperature ◽  
Temperature Shear

Rheological behavior of SAN/PC blends under extremely high shear rate

1989 ◽  
Vol 37 (7) ◽  
pp. 1837-1853 ◽  
Author(s):  
Hideroh Takahashi ◽  
Takaaki Matsuoka ◽  
Takashi Ohta ◽  
Kenzo Fukumori ◽  
Toshio Kurauchi ◽  
...  
Keyword(s):  
Shear Rate ◽  
Rheological Behavior ◽  
High Shear Rate ◽  
High Shear

scholarly journals An Experimental Study on Human Milk Rheology: Behavior Changes from External Factors

Fluids ◽  
2020 ◽  
Vol 5 (2) ◽  
pp. 42 ◽  
Author(s):  
Diana Alatalo ◽  
Fatemeh Hassanipour
Keyword(s):  
Experimental Study ◽  
Shear Rate ◽  
Human Milk ◽  
Rheological Behavior ◽  
Tube Feeding ◽  
External Factors ◽  
Behavior Changes ◽  
Nutrient Losses ◽  
Thixotropic Behavior ◽  
Temperature Storage

The influence of external factors, including temperature, storage, aging, time, and shear rate, on the general rheological behavior of raw human milk is investigated. Rotational and oscillatory experiments were performed. Human milk showed non-Newtonian, shear-thinning, thixotropic behavior with both yield and flow stresses. Storage and aging increased milk density and decreased viscosity. In general, increases in temperature lowered density and viscosity with periods of inconsistent behavior noted between 6–16 ∘ C and over 40 ∘ C. Non-homogeneous breakdown between the yield and flow stresses was found which, when coupled with thixotropy, helps identify the source of nutrient losses during tube feeding.

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