scholarly journals Effect of Coarse Particle Volume Fraction on the Yield Stress of Muddy Sediments from Marennes Oléron Bay

2010 ◽  
Vol 2010 ◽  
pp. 1-6 ◽  
Author(s):  
A. Pantet ◽  
S. Robert ◽  
S. Jarny ◽  
S. Kervella
Keyword(s):  
Yield Stress ◽  
Volume Fraction ◽  
Particle Volume Fraction ◽  
Fine Fraction ◽  
General Description ◽  
Measurement Sensitivity ◽  
Particle Volume ◽  
Fine Sediments ◽  
Sandy Material ◽  
Muddy Sediments

Coastal erosion results from a combination of various factors, both natural and humaninduced, which have different time and space patterns. In addition, uncertainties still remain about the interactions of the forcing agents, as well as on the significance of non-local causes of erosion. We focused about the surface sediments in the Marennes Oléron bay, after a general description of the site that has many various activities. The superficial sediments show a mechanical behavior, mainly depends on the fine fraction for a composition that contains up to 60% of sandy material. Fine sediments fraction has a typical yield stress depending naturally of concentration or water content. This yield could be modified slightly or significantly by adding silt or sand. As a result, the rheological measurement sensitivity allows us to characterize five typical sediments that correlate with solid fraction and fine fraction.

Rheological Study of Micro Particle Laden Polymeric Thermal Interface Materials: Part 2 — Modeling

2002 ◽  
Author(s):  
Ravi S. Prasher ◽  
Jim Shipley ◽  
Suzana Prstic ◽  
Paul Koning ◽  
Jin-Lin Wang
Keyword(s):  
Thermal Conductivity ◽  
Thermal Resistance ◽  
Yield Stress ◽  
Volume Fraction ◽  
Particle Volume Fraction ◽  
Thermal Interface Materials ◽  
Particle Volume ◽  
Thermal Interface ◽  
Complete Set ◽  
Interface Materials

Currently there are no models to predict the thickness or the bondline thickness (BLT) of particle laden polymeric thermal interface materials (TIM) for parameters such as particle volume fraction and pressure. TIMs are used to reduce the thermal resistance. Typically this is achieved by increasing the thermal conductivity of these TIMs by increasing the particle volume fraction, however increasing the particle volume fraction also increases the BLT. Therefore, increasing the particle volume fraction may lead to an increase in the thermal resistance after certain volume fraction. This paper introduces a model for the prediction of the BLT of these particle laden TIMs. Currently thermal conductivity is the only metric for differentiating one TIM formulation from another. The model developed in this paper introduces another metric: the yield stress of these TIMs. Thermal conductivity and the yield stress together constitute the complete set of material parameters needed to define the thermal performance of particle laden TIMs.

Microstructure and Mechanical Properties of High Strength Al2O3p/6061Al Composites

2007 ◽  
Vol 353-358 ◽  
pp. 1390-1393
Author(s):  
Bai Feng Luan ◽  
Gao Hui Wu ◽  
Qing Liu ◽  
Niels Hansen ◽  
Ting Quan Lei
Keyword(s):  
Mechanical Properties ◽  
Yield Stress ◽  
Volume Fraction ◽  
Particle Volume Fraction ◽  
Hot Extrusion ◽  
High Strength ◽  
Dispersion Strengthening ◽  
Particle Volume ◽  
Microstructure And Mechanical Properties ◽  
Before And After

An experimental study of microstructure and mechanical properties in the Al2O3 particulate reinforced 6061 Aluminum composites has been used to determine the effect of extrusion and particle volume fraction (20, 26, 30, 40, 50, 60%Vf) in deformed metal matrix composites. The microstructure of Al2O3 /6061Al composite before and after hot extrusion is investigated by TEM and SEM. Results show that dislocation and subgrain generated after hot extrusion as well as the particle distribution of composite become more uniform with extrusion ratio of 10:1. The ultimate strength, yield strength and elongation of the composite also increase after hot extrusion. Dispersion strengthening and subgrain boundary strengthening is discussed and also the effect of precipitate introduced by heat treatment both after casting and after extrusion. The yield stress (0.2% offset) of the composites has been calculated and predicted using a standard dislocation hardening model. Whilst the correlation between this and the measured value of yield stress obtained in previous experimental test is reasonable.

scholarly journals Effect of coarse particle volume fraction on the yield stress and thixotropy of cementitious materials

2008 ◽  
Vol 38 (11) ◽  
pp. 1276-1285 ◽  
Author(s):  
Fabien Mahaut ◽  
Samir Mokéddem ◽  
Xavier Chateau ◽  
Nicolas Roussel ◽  
Guillaume Ovarlez
Keyword(s):  
Yield Stress ◽  
Volume Fraction ◽  
Particle Volume Fraction ◽  
Cementitious Materials ◽  
Coarse Particle ◽  
Particle Volume

scholarly journals Apparent yield stress in rigid fibre suspensions: the role of attractive colloidal interactions

2016 ◽  
Vol 802 ◽  
pp. 611-633 ◽  
Author(s):  
S. Bounoua ◽  
E. Lemaire ◽  
J. Férec ◽  
G. Ausias ◽  
A. Zubarev ◽  
...  
Keyword(s):  
Yield Stress ◽  
Volume Fraction ◽  
Particle Volume Fraction ◽  
Van Der Waals ◽  
Simple Shear Flow ◽  
Average Particle ◽  
Particle Volume ◽  
Friction Forces ◽  
Aspect Ratios ◽  
Fibre Suspensions

This work is focused on the modelling of the shear and normal stresses in fibre suspensions that are subjected to a simple shear flow in the presence of short-range lubrication forces, van der Waals and electrostatic forces, as well as solid friction forces between fibres. All of these forces are weighed by the contact probability. The theory is developed for attractive fibres with van der Waals interaction dominating over electrostatic repulsion. The model predicts a simple Bingham law for both the shear stress and the first normal stress difference, with the apparent shear and normal yield stresses proportional to the second and the third power of the particle volume fraction respectively. The model is applied to the experimental data of Rakatekar et al. (Adv. Mater., vol. 21, 2009, pp. 874–878) and Natale et al. (AIChE J., vol. 60, 2014, pp. 1476–1487) on suspensions of carbon nanotubes dispersed in a Newtonian epoxy resin. It reproduces well the quadratic dependence of the apparent yield stress on the particle volume fraction $(\unicode[STIX]{x1D70E}_{Y}\propto \unicode[STIX]{x1D719}^{2})$ for average particle aspect ratios of $r=160$ and 1200, while it underpredicts the power-law exponent for $r=80$ (always predicting $\unicode[STIX]{x1D719}^{2}$ behaviour instead of $\unicode[STIX]{x1D719}^{3.2}$).

scholarly journals Cold Forming of Al-TiB2 Composites Fabricated by SPS: A Computational Experimental Study

Materials ◽  
2020 ◽  
Vol 13 (16) ◽  
pp. 3456 ◽  
Author(s):  
Elad Priel ◽  
Nissim U. Navi ◽  
Brigit Mittelman ◽  
Nir Trabelsi ◽  
Moshe Levi ◽  
...  
Keyword(s):  
Yield Stress ◽  
Damage Mechanics ◽  
Mechanical Response ◽  
Volume Fraction ◽  
Particle Volume Fraction ◽  
Continuum Damage Mechanics ◽  
Tib2 Particle ◽  
Particle Volume ◽  
Cold Forming ◽  
Effective Yield

The mechanical response and failure of Al-TiB2 composites fabricated by Spark Plasma Sintering (SPS) were investigated. The effective flow stress at room temperature for different TiB2 particle volume fractions between 0% and 15% was determined using compression experiments on cylindrical specimens in conjunction with an iterative computational methodology. A different set of experiments on tapered specimens was used to validate the effective flow curves by comparing experimental force–displacement curves and deformation patterns to the ones obtained from the computations. Using a continuum damage mechanics approach, the experiments were also used to construct effective failure curves for each material composition. It was demonstrated that the fracture modes observed in the different experiments could be reproduced in the computations. The results show that increasing the TiB2 particle volume fraction to 10% results in an increase in material effective yield stress and a decrease in hardening. For a particle volume fraction of 15%, the effective yield stress decreases with no significant influence on the hardening slope. The ductility (workability) of the composite decreases with increasing particle volume fraction.

CHARACTERISTICS OF A YIELD STRESS SCALING FUNCTION FOR ELECTRORHEOLOGICAL FLUIDS

2002 ◽  
Vol 16 (17n18) ◽  
pp. 2636-2642 ◽  
Author(s):  
H. J. CHOI ◽  
J. W. KIM ◽  
M. S. CHO ◽  
C. A. KIM ◽  
M. S. JHON
Keyword(s):  
Field Strength ◽  
Electric Field ◽  
Electric Field Strength ◽  
Yield Stress ◽  
Volume Fraction ◽  
Particle Volume Fraction ◽  
Critical Evaluation ◽  
Particle Volume ◽  
Scaling Equation ◽  
Er Fluids

The electrorheological (ER) fluids exhibit a drastic change in rheological and electrical properties. Among these properties, yield stress is one of the critical evaluation parameters of the performance of ER devices. The published experimental data of yield dependence on the electric field strength and particle volume fraction are inconsistent due to the time dependence of material properties and measuring conditions. In this paper, we present a universal function, descriptive of the normalized yield stress, via scaling of the applied electric field strength. This scaling equation hybridizes both the polarization and conductivity models. Yield stress data for various ER fluids are collapsed onto a single curve for a broad range of electric field strengths, suggesting that the proposed scaling equation is adequate for predicting the ER property. Furthermore, the yield stresses, obtained from two different measuring techniques (static and dynamics methods), were also examined.

scholarly journals Performance improvement of double-tube gas cooler in CO2 refrigeration system using nanofluids

2015 ◽  
Vol 19 (1) ◽  
pp. 109-118 ◽  
Author(s):  
Jahar Sarkar
Keyword(s):  
Performance Improvement ◽  
Volume Fraction ◽  
Particle Volume Fraction ◽  
Cooling Capacity ◽  
Inlet Temperature ◽  
Refrigeration Cycle ◽  
Particle Volume ◽  
Transcritical Carbon Dioxide ◽  
The Given ◽  
Theoretical Analyses

The theoretical analyses of the double-tube gas cooler in transcritical carbon dioxide refrigeration cycle have been performed to study the performance improvement of gas cooler as well as CO2 cycle using Al2O3, TiO2, CuO and Cu nanofluids as coolants. Effects of various operating parameters (nanofluid inlet temperature and mass flow rate, CO2 pressure and particle volume fraction) are studied as well. Use of nanofluid as coolant in double-tube gas cooler of CO2 cycle improves the gas cooler effectiveness, cooling capacity and COP without penalty of pumping power. The CO2 cycle yields best performance using Al2O3-H2O as a coolant in double-tube gas cooler followed by TiO2-H2O, CuO-H2O and Cu-H2O. The maximum cooling COP improvement of transcritical CO2 cycle for Al2O3-H2O is 25.4%, whereas that for TiO2-H2O is 23.8%, for CuO-H2O is 20.2% and for Cu-H2O is 16.2% for the given ranges of study. Study shows that the nanofluid may effectively use as coolant in double-tube gas cooler to improve the performance of transcritical CO2 refrigeration cycle.

A simulation and experimental study on particle volume fraction of PMMA suspension in centrifugal fields

2021 ◽  
Author(s):  
Yosephus Ardean Kurnianto Prayitno ◽  
Tong Zhao ◽  
Yoshiyuki Iso ◽  
Masahiro Takei
Keyword(s):  
Experimental Study ◽  
Volume Fraction ◽  
Particle Volume Fraction ◽  
Particle Volume
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