Composition – Property Relations in Shear Thickening Fluids

2014 ◽  
Vol 87 ◽  
pp. 91-97
Author(s):  
Łukasz Wierzbicki ◽  
Marcin Leonowicz
Keyword(s):  
High Strain ◽  
Volume Fraction ◽  
Solid Phase ◽  
Loss Modulus ◽  
Shear Thickening ◽  
Complex Viscosity ◽  
High Viscosity ◽  
Polypropylene Glycol ◽  
Shear Thickening Fluids ◽  
Composition Property

It was shown that fumed silica particles (FS), dispersed in polypropylene glycol (PPG), form shear thickening fluids (STF). PPGs with different molar mass were tested. The best combination of the properties (high viscosity, obtained at high shear rate) present the fluids composed of 7 nm FS and PPG 425. The highest volume fraction of FS, which was possible to disperse in PPG 425, was 25%. This fluid exhibited the highest viscosity. The highest magnitude of shear thickening effect was obtained, however, for 17.5 vol.% of the solid phase. Dynamic oscillatory shear experiments were conducted at either a constant amplitude or frequency. The constant strain amplitude tests showed, that for the frequency sweep, the systems showed viscous properties, except that of 25 vol.% of FS in PPG 425, which exhibited elastic properties in almost entire range of the frequency investigated. For the constant strain sweep, for low strains, the elastic modulus and loss modulus were hardly dependent on the strain, but for relatively high strain, this dependency was increasing. Also the complex viscosity was also growing for high strain values.

Rheological Fluids for Energy Absorbing Systems

2013 ◽  
Vol 440 ◽  
pp. 13-18 ◽  
Author(s):  
Marcin Leonowicz ◽  
Joanna Kozłowska ◽  
Łukasz Wierzbicki
Keyword(s):  
Magnetic Field ◽  
Carbonyl Iron ◽  
Volume Fraction ◽  
Loss Modulus ◽  
Shear Thickening ◽  
High Viscosity ◽  
Polypropylene Glycol ◽  
Magneto Rheological ◽  
Energy Absorbing ◽  
Protective Performance

Two types of non-Newtonian fluids, magneto rheological (MRF) and shear thickening (STF) fluids, respectively were chosen as candidates for energy dissipation study in smart body armour. A series of magneto rheological fluids was synthesized on a basis of synthetic oil and carbonyl iron. The shear modules for the MRF containing 75 wt% of carbonyl iron, obtained in a magnetic field of 230 kA/m were as follows: complex shear modulus G* - 1.2 MPa, storage modulus G-1.2 MPa and loss modulus G 0.35 MPa. The studies revealed also that the silica fumed, dispersed in polypropylene glycol or polyethylene oxide, demonstrates shear thickening properties. The best combination of the properties (high viscosity, obtained at high shear rate) represents the material composed of the silica fumed (SF) and PEO300. Change of the volume fraction of the SF and variation of the molecular weight of the oligomer enables tailoring of the STF properties. Ballistic tests revealed that the structures containing PE bags with MRF (in magnetic field) or STF can enhance the protective performance of body armours providing their flexibility.

Shear Thickening Behaviour of Composite Propellant Suspension under Oscillatory Shear

2016 ◽  
Vol 66 (3) ◽  
pp. 222 ◽  
Author(s):  
D. Singh ◽  
G. Dombe ◽  
C. Bhongale ◽  
P. P. Singh ◽  
Mehilal Maurya ◽  
...  
Keyword(s):  
Strain Amplitude ◽  
Loss Modulus ◽  
Shear Thickening ◽  
Rheological Behaviour ◽  
Complex Viscosity ◽  
Solid Particles ◽  
Dynamic Moduli ◽  
Composite Propellant ◽  
Plateau Region ◽  
Temperature Constant

Composite propellant suspensions consist of highly filled polymeric system wherein solid particles of different sizes and shapes are dispersed in a polymeric matrix. The rheological behaviour of a propellant suspension is characterised by viscoplasticity and shear rate and time dependant viscosity. The behaviour of composite propellant suspension has been studied under amplitude sweep test where tests were performed by continuously varying strain amplitude (strain in %, γ) by keeping the frequency and temperature constant and results are plotted in terms of log γ (strain amplitude) vs logGʹ and logGʺ (Storage modulus and loss modulus, respectively). It is clear from amplitude sweep test that dynamic moduli and complex viscosity show marked increase at critical strain amplitude after a plateau region, infering a shear thickening behaviour.

scholarly journals Impact of the Carbon Nanofillers Addition on Rheology and Absorption Ability of Composite Shear Thickening Fluids

Materials ◽  
2020 ◽  
Vol 13 (17) ◽  
pp. 3870
Author(s):  
Paulina Nakonieczna-Dąbrowska ◽  
Rafał Wróblewski ◽  
Magdalena Płocińska ◽  
Marcin Leonowicz
Keyword(s):  
Carbon Nanotubes ◽  
Graphene Oxide ◽  
Rheological Behavior ◽  
Shear Thickening ◽  
High Energy ◽  
Polypropylene Glycol ◽  
Shear Thickening Fluids ◽  
Carbon Nanofillers ◽  
Energy Absorbing ◽  
Composite Shear

Synthesis and characterization of composite shear thickening fluids (STFs) containing carbon nanofillers are presented. Shear thickening fluids have attracted particular scientific and technological interest due to their unique ability to abruptly increase viscosity in the case of a sudden impact. The fluids have been developed as a potential component of products with high energy absorbing efficiency. This study reports on the rheological behavior, stability, and microstructure of the STFs modified with the following carbon nanofillers: multi-walled carbon nanotubes, reduced graphene oxide, graphene oxide, and carbon black. In the current experiment, the basic STF was made as a suspension of silica particles with a diameter of 500 nm in polypropylene glycol and with a molar mass of 2000 g/mol. The STF was modified with carbon nanofillers in the following proportions: 0.05, 0.15, and 0.25 vol.%. The addition of the carbon nanofillers modified the rheological behavior and impact absorption ability; for the STF containing 0.25 vol.% of carbon nanotubes, an increase of force absorption up to 12% was observed.

scholarly journals Thermal stability of the elastomeric anti-trauma pad

2017 ◽  
Vol 19 (2) ◽  
pp. 93-100
Author(s):  
Karolina Olszewska ◽  
Dorota Zielinska ◽  
Marcin H. Struszczyk ◽  
Łukasz Wierzbicki ◽  
Marcin K. Leonowicz
Keyword(s):  
Aging Process ◽  
Volume Fraction ◽  
Accelerated Aging ◽  
Shear Thickening ◽  
Chemical Degradation ◽  
Polypropylene Glycol ◽  
Shear Thickening Fluid ◽  
Vis Spectroscopy ◽  
Ballistic Properties ◽  
Thermographic Analysis

AbstractThe elastomeric anti-trauma pad (EA-TP) based on shear thickening fluid (STF) has been developed. Dynamic oscillatory shear experiment was conducted at constant strain amplitude of 5%. STF composed of 25% of volume fraction of 7 nm Fumed Silica, dispersed in polypropylene glycol with molar mass 400 gmol−1shows elastic properties in entire investigated range of the frequency. Ballistic tests of EA-TP with 7.62 mm × 39 mm PS bullets were performed according to the PN-V-87000:2011 standard. The studies revealed about 60% reduction of the average backface signature depth (BSD) for the EA-TP, when compared to the nowadays commonly used soft insert. The ATR-FTIR analysis confirmed slight impact of the elevated temperature and air (oxygen) on the chemical degradation of the EA-TP surface. The UV-VIS spectroscopy has allowed to notice colour deviation of the aged samples towards green and yellow, as well as lack of dye resistance to accelerated aging process. Thermographic analysis has shown no visible changes of the EA-TP surface and sub-surface during accelerated aging process. The aforementioned small changes on the surface of EA-TP did not affect the ballistic properties of composite armour. EA-TP insert maintains ballistic properties after accelerated aging process which was simulating the period of 6 years according to ASTM F1980 – 07:2002 standard.

Effect of Alumina Addition on the Rheological Behavior of Shear Thickening Fluids

2019 ◽  
Vol 798 ◽  
pp. 331-336
Author(s):  
Natnicha Nuampakdee ◽  
Sujarinee Sinchai ◽  
Chaiwut Gamonpilas
Keyword(s):  
Rheological Behavior ◽  
Colloidal Particles ◽  
Volume Fraction ◽  
Shear Thickening ◽  
Body Armor ◽  
Shear Stresses ◽  
Hard Material ◽  
Shear Rates ◽  
Shear Thickening Fluids ◽  
Alumina Addition

Shear thickening fluids (STF) have attracted much attention in many applications including body armor. In this study, suspensions of silica colloidal particles and polyethylene glycol fluid were prepared at varying volume fractions φ = 0.3 to 0.52 and their rheological behavior was investigated. It was found that the suspensions exhibited a Newtonian behavior for φ < 0.4, whilst a shear thinning followed by a thickening behavior could clearly be observed for φ > 0.4. Furthermore, the critical shear rates for the onset of shear thickening was found to decrease with increasing silica volume fraction but the corresponding critical shear stresses were independent of the volume fraction. To improve the ballistic protective performance, small amount of hard material particles, such as alumina, were added into the silica suspension of φ = 0.5. It was shown that the critical shear rates of the reinforced-STFs decreased with increasing volume fraction and decreasing alumina particle size. However, higher thickening ratio was observed for the alumina additive with agglomerated structure and this ratio increased with increasing alumina volume fraction.

Magnetorheology of Multiwalled Carbon Nanotube Mineral Dispersions

2006 ◽  
Author(s):  
Zhengtao Yang ◽  
Ali Shaito ◽  
Nandika Anne D'Souza
Keyword(s):  
Magnetic Field ◽  
Carbon Nanotube ◽  
Power Law ◽  
Volume Fraction ◽  
Loss Modulus ◽  
Complex Viscosity ◽  
Mineral Oil ◽  
Multiwalled Carbon ◽  
Strain Sweep ◽  
Dynamic Yield

Multi-walled carbon nanotube (MWCNT) were dispersed in mineral oil and the magnetorheological response was measured. 0.5, 1.5 and 2.53 vol% nanotubes were dispersed in mineral oil. Strain sweep, frequency sweep, magneto sweep and steady shear tests were conducted in various magnetic field strengths. Storage modulus G', loss modulus G", complex viscosity η* and dynamic yield stress τy increased with magnetic field, which was partially attributed to the increasing degree of alignment of nanotubes in stronger magnetic field. G' and G" of MWCNT/mineral oil dispersions scaled with nanotube volume fraction φ by a power-law. The shear thinning behavior of MWCNT/mo dispersions followed the Ostwald-de Waele or power law.

Impact Resistance of Liquid Body Armor Utilizing Shear Thickening Fluids: A Computational Study

2015 ◽  
Author(s):  
Fardin Khalili ◽  
Federico De Paoli ◽  
Rasim Guldiken
Keyword(s):  
Multiphase Flow ◽  
High Speed ◽  
Volume Fraction ◽  
Computational Study ◽  
Shear Thickening ◽  
Ballistic Performance ◽  
High Quality ◽  
Liquid Body ◽  
Shear Thickening Fluids ◽  
The Impact

Since the creation of advanced knives and firearms with high rates of speed, safety has always been a vital issue for armed forces. A disadvantage of a regular fabric Kevlar is that, although it has an effective resistance against the impact of low-speed bullets, it reveals its weakness in the case of a stab wound and high-speed bullets. Under these circumstances, a new executable technology of fibers that improves the ballistic performance of the materials utilized in body armors is an essential necessity to build high quality and protective vests which are perfectly bulletproof. The purpose of this study is to investigate the physics and concepts of shear thickening fluids and perform a computational CFD simulation of liquid body armors which consist of a combination of polyethylene glycol liquid and nanoparticles of silica. A model of multiphase flow environment with STFKevlar, as a representative of the non-Newtonian shear thickening fluid (STF), is simulated in STAR-CCM+ in order to analyze the behavior of STFs under impact and performance of novel liquid body armors. In the current simulation, Eulerian multiphase flow and volume of fluid (VOF) are applied to generate three discrete regions and determine the volume fraction of each phase including gas, non-Newtonian liquid and solid which represent air, STFKevlar and bullet, respectively. Moreover, dynamic fluid body interactions (DFBI) and overset mesh are utilized to consider the interactions between the regions and forces applied. In this study, the properties of the bullet are based on characteristics of a regular pistol bullet, and it approaches the STFKevlar with the constant speed of 400 m/s. The results show that the non-Newtonian material is initially at equilibrium state and while the bullet approaches the STFKevlar, it acts like a shear thinning fluid. As a high-speed bullet nears the STFKevlar, it absorbs the significant amount of energy that is applied by the bullet. Consequently, the bullet stops penetrating the STFKevlar in a very small fraction of time due to the considerable increase in viscosity. As the shear rate increases over a certain critical value, viscosity increases remarkably which is the main characteristic of shear thickening transition and finally, it reaches to its maximum value of viscosity in approximately 8 × 10−5sec. In addition, a bullet applies a considerable amount of force on any Kevlar due to its high velocity and kinetic energy; however, the high resistant STFKevlar is approved as a high quality and protective vests which stops the bullet in 6 × 10−4sec.

scholarly journals Investigação do comportamento viscoelástico de amostras de licor negro oriundas do processo de polpação Kraft da Cenibra-MG à 25 oc

2021 ◽  
Vol 3 (4) ◽  
pp. 2411-2425
Author(s):  
Ângelo M. L. Denadai ◽  
Euler T. Dos Santos ◽  
Humberto L. Dos Santos ◽  
José M. Q. Moreira ◽  
Fernando C. De Oliveira ◽  
...  
Keyword(s):  
Shear Rate ◽  
Yield Stress ◽  
Loss Modulus ◽  
Viscoelastic Behavior ◽  
Shear Thickening ◽  
Complex Viscosity ◽  
Kraft Pulping ◽  
Chemical Recovery ◽  
Molecular Fragmentation ◽  
Black Liquors

RESUMO O comportamento viscoelástico dos licores negros de eucalipto (LN) do processo de polpação Kraft da CENIBRA foi avaliado a 25 oC, na ausência (LNSC) e na presença (LNCC) de cinzas da ebulição da recuperação química, que são geralmente misturadas com licores negros para melhorar a eficiência da recuperação química. As amostras foram tosquiadas em campos rotativos e oscilatórios, mostrando os comportamentos de cisalhamento e cisalhamento dependentes da taxa de cisalhamento aplicada. A viscosidade complexa - *, o módulo de armazenamento e perda - G' e G'', e a tensão de rendimento 0 para LNSC foram todos muito superiores ao LNCC, provavelmente devido à fragmentação molecular causada pela adição de cinzas.   ABSTRACT The viscoelastic behavior of eucalyptus black liquors (LN) from CENIBRA Kraft pulping process was evaluated at 25 oC, in absence (LNSC) and in presence (LNCC) of ash from chemical recovery boiling, which are usually mixed with black liquors to improve the efficiency of chemical recovery. The samples were sheared upon rotational and oscillatory fields, showing booth shear-thickening and shear-thinning behaviors dependent of applied shear rate. The complex viscosity – h*, storage and loss modulus – G’ and G’’, and yield stress s0 for LNSC were all very higher than LNCC, probably due the molecular fragmentation caused by addition of ashes.

Sign in / Sign up

Export Citation Format

Share Document