ArticlePDF Available

SHEAR THICKENING FLUIDS (STFS); DEFINITION, THE AFFECTING FACTORS, AND THEIR GENERAL APPLICATIONS: A REVIEW

Authors:

Abstract and Figures

Shear thickening fluids STFs are a new kind of materials that consist of nano/micro particles that dispersed in another material such as polymer. In this review paper, the definition of this type of materials and the mechanism of its work are explained. In addition, the main factors that can effect on this behavior and their applications in different area from simple applications to complex applications are shown briefly.
Content may be subject to copyright.
NOVATEUR PUBLICATIONS
JournalNX- A Multidisciplinary Peer Reviewed Journal
ISSN No: 2581 - 4230
VOLUME 8, ISSUE 5, May -2022
74 | P a g e
SHEAR THICKENING FLUIDS (STFS); DEFINITION, THE AFFECTING
FACTORS, AND THEIR GENERAL APPLICATIONS: A REVIEW
Nabeel Hasan Al-Mutairi
Polymers and Petrochemical Engineering Industries Department,
College of Materials Engineering, University of Babylon, Al-Hilla, Iraq
E-mail: nabeelemg90@gmail.com.
ABSTRACT:
Shear thickening fluids STFs are a new
kind of materials that consist of nano/micro
particles that dispersed in another material
such as polymer. In this review paper, the
definition of this type of materials and the
mechanism of its work are explained. In
addition, the main factors that can effect on
this behavior and their applications in
different area from simple applications to
complex applications are shown briefly.
Keywords: Shear thickening fluids; STFs;
Body armor; Dilatant; Non-Newtonian flow.
I. INTRODUCTION TO SHEAR THICKENING
FLUIDS (STFS):
This type of fluid has a non-Newtonian
behavior as its viscosity increases with
increasing shear rate; it is often seen in
concentrated colloidal dispersion. This kind of
materials show a solid like behavior for a split
second when the stress is applied on the material
and return to its liquid behavior after the
removal of stress[1][4]. Figure 1 shows the two
main types of fluids: Non-Newtonian (the
viscosity change with changing the shear rate)
such as shear thinning (pseudoplastic) and shear
thickening (dilatent), and Newtonian fluids (the
viscosity constant with shear rate change)[5].
Figure 1: Types of fluids[5].
At low shear rates, shear thinning
behavior appears, and with increasing shear rate,
the viscosity increases to a higher value and
turns into shear thickening. These fluids are
characterized by the fact that removing the shear
stress leads to a decrease in viscosity. This type
of fluid has good mechanical properties because
of the unique rheological properties that make it
distinctive applications, as shown in Figure 2 [6].
Figure 2: The shear thickening fluid behavior [7].
NOVATEUR PUBLICATIONS
JournalNX- A Multidisciplinary Peer Reviewed Journal
ISSN No: 2581 - 4230
VOLUME 8, ISSUE 5, May -2022
75 | P a g e
Figure 2 represents the general scheme of
STF, which consists of three regions: The first
region represents the occurrence of shear
thinning that is evident at shear rates that are
less than the critical shear rate γc, the second
region represents the shear thickening that
occurs between the critical shear γc and the
greatest shear, and the last region is the
occurrence of shear thinning.
II. FACTORS AFFECTING ON SHEAR
THICKENING FLUIDS:
Shear thickening behavior is affected by
many factors related to the dispersed medium,
including volume fraction, particle size, shape
and dispersion, and also depends on the
properties of the continuous medium.
A. The volume fraction of the added particles has
a great effect on the appearance of the shear
thickening behaviour, as by increasing the
volume fraction, the critical shear rate appears in
a closer area, which means an increase in
viscosity, as shown by Figure 3 and 4.
Figure 3: Shear rate/Viscosity curve as a function
of different volume fraction[8].
Figure 4: Critical shear rate onset dependence on
the volume fraction[9].
B. Particles size: particle size has an opposite
effect on shear thickening, as the larger the
particle size, the less shear thickening appears,
as shown in Figure 4 [10].
Figure 4: Particle size effect on the shear
thickening behavior[10].
C. The particles size distribution: The blocks that
consist of different sizes of particles are more
compact in that the small particles fill the spaces
between the large particles. when shear stress is
applied, the small particles act as a lubricant for
the flow of large particles and thus lead to a
decrease in the viscosity of the fluid, as shown by
Figure 5 and 6 [11].
Figure 5: SEM image of large and small particles
in shear thickening fluid[12].
Figure 6: The effect of particle diameter (left)
and particle size distribution (right) on the shear
thickening behavior [13].
NOVATEUR PUBLICATIONS
JournalNX- A Multidisciplinary Peer Reviewed Journal
ISSN No: 2581 - 4230
VOLUME 8, ISSUE 5, May -2022
76 | P a g e
D. The shape of the particles: The particle
shape has a great effect on the shear thickening
behavior. Studies have shown that the rod-
shaped particles are more effective than the plate
because the rod arranges itself in the direction of
flow. Spherical particles produce higher viscosity
because they disperse higher energy, as shown
by figure 7 [11].
Figure 7: The effect of different shape of particles
on the viscosity/shear rate behavior[14]and [4].
E. Attractive forces between particles: The
attraction between particles has an important
effect to obtain the required rheological
properties, as the forces must be stable between
particles. To get shear thickening there should be
no attraction between the particles as shown by
figure 8 [11].
Figure 8: The chemical induction effect on the
shear thickening behavior, (flocculated-no
interaction between the particles/shear
thinning), and (deflocculated- there are an
interaction between the particles/shear
thickening)[14]and [4].
III. APPLICATION OF SHEAR THICKENING FLUIDS:
These liquids have many different
applications from industrial applications to
medical applications, as the use of these liquids
in a specific application depends on the materials
used in terms of the type of particles as well as
the type of polymer. In this section, some of the
important application are listed.
A. Shock absorbers and suspension
systems, which consist of an insulating fluid and
polar particles called ER fluids, are affected by an
electric field. Magnetic particles can be used and
MR fluids are known to be affected by the
magnetic field[15].
Figure 9: Shock absorber system for
automotive[15].
B. Shear thickening fluids are used for the
purpose of protection against sudden shock to
the screens of devices, especially smart devices,
and automotives (paint, and mirrors) where the
surface of the screen is covered with this type of
material[16].
C. Shear thickening fluid is used for the
purpose of smoothing surfaces, especially
complex surfaces, as it is an easy, fast and low
cost method. SiC particles are characterized by
high hardness and strength, which are used for
the cleaning and smoothing of rust and oxidized
objects, as in figure 10 [17].
NOVATEUR PUBLICATIONS
JournalNX- A Multidisciplinary Peer Reviewed Journal
ISSN No: 2581 - 4230
VOLUME 8, ISSUE 5, May -2022
77 | P a g e
Figure 10: Shear thickening fluid and SiC
particles for polishing and cleaning[17].
D. Shear thickening fluids are used in oil
extraction operations during drilling to prevent
an explosion in the well when the drill reaches a
gap containing gases at high pressure[18].
E. The most common and widely used
application is in the field of armor industry to
protect people from stabbing and bullets, where
layers of Kevlar or aramid fibers are used and
covered with Shear thickening fluid, thus
providing protection, ease of movement and low
cost. As the number of layers used is less in the
case of Shear thickening fluid as in figure 11[19].
Personal protection of the body from dangers
and injuries is an important need for people,
especially soldiers and policemen, to protect
them from attacks and attacks that they may
encounter in their daily work [14].
This led to the manufacture of clothing or
covers that are resistant to these conditions to
protect them from any attacks and attacks that
may lead to their death. These protective
clothing are called shields and are defined as any
cover used to protect the body from any danger,
external influence or violent strike. Animal skins,
natural fibres, cotton, silk and iron have been
used as shields throughout history[20], [21].
The shields used today should not only be
stabbing resistant, but rather bulletproof. It is
made of metal, ceramic and solid polymeric
panels with several layers to provide adequate
protection. The problem with these armors is the
weight as well as the restriction of movement, so
the use of nano-liquids known as liquid armor
that adopts the shear thickening behavior has
been resorted to[22], [23].
Figure 11: Kevlar woven fibers and shear
thickening fluid for body armor[24].
IV. CONCLUSION;
This review paper discussed the shear
thickening fluids because it’s a new type of
materials that have properties of different
materials. Its shown that under specific shear
rate the material will behave like shear thinning
and after the shear rate increase and exceeds
critical shear rate the material will show the
solid like behavior shear thickening behavior. In
addition, its shown that there are several factors
effect on the behavior of this material such as
volume fraction, particle size and its distribution,
particle shape, and attraction forces, some
factors make this behavior appear at low shear
rates while other factors make it appear at high
shear rates. In addition, it's found that there are
several applications of these material, the kind of
application depends on the dispersed particle
type.
REFERENCES:
1) E. E. Bischoff White, M. Chellamuthu, and J. P.
Rothstein, “Extensional rheology of a shear-
thickening cornstarch and water suspension,”
Rheol. acta, vol. 49, no. 2, pp. 119129, 2010.
2) A. Srivastava, A. Majumdar, and B. S. Butola,
“Improving the impact resistance of textile
structures by using shear thickening fluids: a
review,” Crit. Rev. Solid State Mater. Sci., vol.
37, no. 2, pp. 115129, 2012.
3) L. Chang, K. Friedrich, A. K. Schlarb, R.
NOVATEUR PUBLICATIONS
JournalNX- A Multidisciplinary Peer Reviewed Journal
ISSN No: 2581 - 4230
VOLUME 8, ISSUE 5, May -2022
78 | P a g e
Tanner, and L. Ye, “Shear-thickening
behaviour of concentrated polymer
dispersions under steady and oscillatory
shear,” J. Mater. Sci., vol. 46, no. 2, pp. 339
346, 2011.
4) M. C. KUŞHAN, S. GÜRGEN, T. ÜNALIR, and S.
ÇEVİK, “A novel approach for armor
applications of shear thickening fluids in
aviation and defense industry,” Int. Sci.
Comm., vol. 1, pp. 179187, 2014.
5) F. Rizzo, F. Pinto, and M. Meo, “Investigation
of silica-based shear thickening fluid in
enhancing composite impact resistance,”
Appl. Compos. Mater., vol. 27, no. 3, pp. 209
229, 2020.
6) F. J. Galindo-Rosales, F. J. Rubio-Hernández,
and A. Sevilla, “An apparent viscosity function
for shear thickening fluids,” J. Nonnewton.
Fluid Mech., vol. 166, no. 56, pp. 321325,
2011.
7) M. Wei, K. Lin, and H. Liu, “Experimental
investigation on hysteretic behavior of a
shear thickening fluid damper,” Struct.
Control Heal. Monit., vol. 26, no. 9, p. e2389,
2019.
8) E. D. Wetzel, Y. S. Lee, R. G. Egres, K. M.
Kirkwood, J. E. Kirkwood, and N. J. Wagner,
“The effect of rheological parameters on the
ballistic properties of shear thickening fluid
(STF)‐kevlar composites,” in AIP conference
proceedings, 2004, vol. 712, no. 1, pp. 288
293.
9) H. A. Barnes, J. F. Hutton, and K. Walters, An
introduction to rheology, vol. 3. Elsevier,
1989.
10) X. Z. Zhang, W. H. Li, and X. L. Gong, “The
rheology of shear thickening fluid (STF) and
the dynamic performance of an STF-filled
damper,” Smart Mater. Struct., vol. 17, no. 3,
p. 35027, 2008.
11) T. Erdoğan, “Development of liquid armor
materials and rheological behavior of shear
thickening fluids (STFs),” Izmir Institute of
Technology, 2011.
12) Y. S. Lee, E. D. Wetzel, and N. J. Wagner, “The
ballistic impact characteristics of Kevlar®
woven fabrics impregnated with a colloidal
shear thickening fluid,” J. Mater. Sci., vol. 38,
no. 13, pp. 28252833, 2003.
13) A. Idźkowska and M. Szafran, “The effect of
nano SiO2 particle size distribution on
rheological behaviour of shear thickening
fluids,” Arch. Metall. Mater., 2013.
14) S. Yıldız, “Synthesis and rheological behavior
of shear thickening fluids (STFs) for liquid
armor applications,” Izmir Institute of
Technology (Turkey), 2013.
15) B. Liu et al., “Mechanical properties of
magneto-sensitive shear thickening fluid
absorber and application potential in a
vehicle,” Compos. Part A Appl. Sci. Manuf., vol.
154, p. 106782, 2022.
16) C. Zhao, X. Gong, S. Wang, W. Jiang, and S.
Xuan, “Shear stiffening gels for intelligent
anti-impact applications,” Cell Reports Phys.
Sci., vol. 1, no. 12, p. 100266, 2020.
17) S. Gürgen and A. Sert, “Polishing operation of
a steel bar in a shear thickening fluid
medium,” Compos. Part B Eng., vol. 175, p.
107127, 2019.
18) C. L. Hamburger, E. N. Drake, M. E. Morrison,
and Y. H. Tsao, “Development and application
of a new fluid for stopping unwanted flows in
and around wellbores,” Exxon Production
Research Co., 1983.
19) R. G. Egres Jr, C. J. Halbach, M. J. Decker, E. D.
Wetzel, and N. J. Wagner, “Stab performance
of shear thickening fluid (STF)fabric
composites for body armor applications,”
development, vol. 1, pp. 112, 2005.
20) N. J. Wagner and E. D. Wetzel, “Protective
fabrics utilizing shear thickening fluids
(STFs),” in Proceedings of the 4th Conf. on
Safety and Protective Fabrics (Pittsburg,
2004, pp. 8894.
21) R. G. Egres Jr et al., “Stab resistance of shear
thickening fluid (STF)Kevlar composites for
body armor applications,” in
NOVATEUR PUBLICATIONS
JournalNX- A Multidisciplinary Peer Reviewed Journal
ISSN No: 2581 - 4230
VOLUME 8, ISSUE 5, May -2022
79 | P a g e
Transformational Science And Technology
For The Current And Future Force: (With CD-
ROM), World Scientific, 2006, pp. 264271.
22) M. J. Decker, C. J. Halbach, C. H. Nam, N. J.
Wagner, and E. D. Wetzel, “Stab resistance of
shear thickening fluid (STF)-treated fabrics,”
Compos. Sci. Technol., vol. 67, no. 34, pp.
565578, 2007.
23) P. V Cavallaro, “Soft body armor: an overview
of materials, manufacturing, testing, and
ballistic impact dynamics,” Naval Undersea
Warfare Center Div Newport RI, 2011.
24) J. Qin, B. Guo, L. Zhang, T. Wang, G. Zhang, and
X. Shi, “Soft armor materials constructed with
Kevlar fabric and a novel shear thickening
fluid,” Compos. Part B Eng., vol. 183, p.
107686, 2020.
... Therefore, this STF property has been applied to reinforce fabrics to improve their resistance to impact loading. 11 In STF, media-particle and particle-particle interaction plays the main role in determining the formation and development of shear-thickening. 12,13 Changing structures after the critical shear rate is mainly induced by hydrodynamic force, which shifts the force equivalence between all the system' constituents by altering particle-particle and media-particle interaction forces. ...
Article
Full-text available
The present study deals with the chemical modification of polyethylene glycol (PEG) based on shear thickening fluids (STFs) and their application to improve the ballistic impact and quasi-static resistance performance of 3D E-glass fabrics. The carrier fluid (PEG 200) was modified with two different agents, oxalic acid and glutaric acid. The modified PEGs were then characterized by FTIR analysis. The rheological analysis of modified STF using glutaric (G/STF) and oxalic acid (O/STF) showed an improvement in peak viscosity by 10.33 and 3.28 times compared to pure STF (P/STF), respectively. Moreover, PEG modification resulted in higher chain length and a higher number of hydrophilic functional groups, representing superior media-particle interaction through abundant H-bonding. As a result of improved viscosity, the ballistic resistance and quasi-static performance of modified STF-treated fabrics were enhanced compared to that of P/STF-treated fabrics. A two-step artificial intelligence regression analysis was performed to predict quasi-static puncture resistance at different puncture speeds. The results showed a strong correlation between the load-deformation behavior and the loading speed.
Article
Full-text available
Next-generation intelligent body armor requires high anti-impact performance, low weight, flexibility, and integration with multifunctional wearable devices. Shear stiffening gel (SSG), a kind of high-molecular-weight polymer with interesting properties such as dynamic boron-oxygen (B-O) weak crosslinks, nonlinear mechanical behavior, and high energy dissipation efficiency, has attracted intensive attention from both scientific and industrial sectors. Due to rate-dependent viscoelastic characteristics, SSG has achieved mechanical enhancement following an increase in the external strain rate. Therefore, it is important to understand the viscoelastic behavior of SSG and its derivatives to design the new type of flexible anti-impact devices. This article is a brief review of the recent advances in SSGs, including preparations, mechanical properties, mechanisms, and practical applications in sensors, energy devices, damper controls, and body armors. Finally, the future development potential of SSG as an intelligent anti-impact material is also forecasted.
Article
Full-text available
In present work the influence of particle size distribution on the dilatant effect of shear thickening fluid was investigated. As a ceramic powder a mixture of silicas 200 and 7 nm in ratio 95:5, 90:10, 85:15, 80:20, 75:25, 50:50 was used. A dispersing agent was poly (propylene glycol) of a molecular weight of 425 g/mol. The as prepared slurries were examined on a rotational rheometer Kinexus Pro with a plate-plate measuring system at room temperature, where the viscosity as a function of shear rate was investigated. The measurement showed that by partially replacing greater particle size by smaller one, it is possible to shift the onset of shear thickening to the higher value of shear rate, however, the decreases of dilatant effect is observed. The influence of particle size distribution on a maximum volume fraction also was investigated. The maximum volume fraction which was passible to obtain was 35 vol%.
Article
Full-text available
This report documents the development of today’s soft body armors including their designs, materials, manufacturing methods, National Institute of Justice ballistic and North Atlantic Treaty Organization fragment threat categories, and qualification testing requirements. Material characteristics are discussed for each of the multiple material dimensional scales, which include the molecular, fiber, yarn, and fabric scales. Ballistic impact effects on single fibers and both single and multilayered woven fabrics are presented as well as numerical models used to depict stress and transverse wave propagations, projectile blunting, and fabric penetration.
Article
Full-text available
The stab resistance of shear thickening fluid (STF)-Kevlar and STF-Nylon fabric composites are investigated and found to exhibit significant improvements over neat fabric targets of equivalent areal density. Specifically, dramatic improvements in puncture resistance (spike threat) are observed under high and low speed loading conditions, while slight increases in cut protection are also observed. These results, combined with improvements in ballistic properties reported in earlier studies (Lee et al., 2002, Lee et al. 2003), indicate that these novel materials could be used to fabricate flexible body armors which provide improved protection against both stab and ballistic threats.
Article
Full-text available
This study reports the ballistic penetration performance of a composite material composed of woven Kevlar fabric impregnated with a colloidal shear thickening fluid (silica particles (450 nm) dispersed in ethylene glycol). The impregnated Kevlar fabric yields a flexible, yet penetration resistant composite material. Fragment simulation projectile (FSP) ballistic penetration measurements at 244 m/s have been performed to demonstrate the efficacy of the novel composite material. The results demonstrate a significant enhancement in ballistic penetration resistance due to the addition of shear thickening fluid to the fabric, without any loss in material flexibility. Furthermore, under these ballistic test conditions, the impregnated fabric targets perform equivalently to neat fabric targets of equal areal density, while offering significantly less thickness and more material flexibility. The enhancement in ballistic performance is shown to be associated with the shear thickening response, and possible mechanisms of fabric-fluid interaction during ballistic impact are identified.
Article
A multifunctional smart material with both shear thickening effect and magnetorheological performance was fabricated by dispersing carbonyl iron powder (CIP) particles into shear thickening fluid, the properties and application potential were tested and analysed. Firstly, the rheological properties of this type of magneto-sensitive shear thickening fluid (MSTF) was tested by a rheometer. Besides, the influence of the current, frequency and amplitude on the mechanical properties of the absorber with MSTF was studied. Finally, the damping force and the variation rules of the Cadillac shock absorber with commercial magnetorheological fluid and MSTF were tested, compared and analysed at different currents and distinct velocities. The influence of the shear thickening effect of MSTF on the damping force in the shock absorber was studied by testing the self-made MSTF and MRF with the CIP fraction from 10% to 70%. This work provided a design idea to improve the shock absorber performance.
Article
This study presents the dynamic stab resistance and quasi-static mechanical properties of soft armor materials constructed with Kevlar fabric impregnated with a novel shear thickening fluid (STF) composed of silica microsphere and ionic liquids (ILs). Rheological results indicate that this STF presents a unique double continuous shear thickening behavior and good conductivity. Both the stab resistance and mechanical properties of the Kevlar fabric are enhanced significantly due to the presence of the STF. With increasing the addition of STF, the stab resistance of the STF-processed Kevlar fabrics (STKF) is enhanced, and the optimal stab resistance is obtained when the STKF contains 34.89 wt % STF. By comparison with the neat Kevlar fabric, the maximum friction between the yarns in the STKF increases by dozens of times, and the tensile strength of the STKF and yarn increases by approximately 2 times and 1.5 times, respectively. Tensile and pull-out tests demonstrate that both filaments and yarns are restrained for the unique double continuous shear thickening of the STF. Furthermore, the STKF has conductivity and the electrical resistance of it has high sensitivity to the applied deformation. The electromagnetic interference shielding of the STKF was as high as 27 dB. These provide a potential to exploit the novel next generation of soft armor with both excellent protective performance and intelligent wearable property.
Article
Shear thickening fluid (STF) has been utilized in several engineering applications due to its increasing viscosity under loading. Although the principal applications are protective structures and vibration attenuation systems, STF was adapted to a manufacturing process in this study. Combining an STF with abrasive particles, we fabricated a polishing suspension in which the STF provides a tough matrix for the abrasive particles. A steel bar was investigated in the polishing tests at two different shear rates which are adjusted to yield a low point and a peak point in the suspension viscosity. According to the results, the process at low viscosity is insufficient to realize the material removal from the specimen surface however, at peak viscosity, the process yields beneficial mechanism for improving the specimen surface finish.
Article
A new shear-thickening fluid (STF) for stopping unwanted flows in and around a wellbore during drilling operations has been developed. This fluid is a pumpable liquid when subjected to the relatively low shear rates inside the drill pipe, but thickens dramatically when sheared through the bit nozzles at a high rate. After shearing through the bit nozzles, the thickened paste can be used to plug a wellbore, or it can be squeezed into either the formation or channels behind casing. This fluid is unique in that it thickens immediately when subjected to high shear rates, and needs no external component to achieve this state. This paper discusses the concept, composition, and properties of this new fluid, as well as the method of applying it. Examples of two types of field applications of the new fluid are included.
Article
The stab resistance of shear thickening fluid (STF)-treated Kevlar® and Nylon fabrics is investigated and found to exhibit significant improvements over neat fabric targets of equivalent areal density. Specifically, dramatic improvements in puncture resistance (spike threat) are observed under high and low speed loading conditions, while slight increases in cut protection (knife threat) are also observed. Studies on the effect of fabric architecture indicate that STF addition provides benefits analogous to the effect of increasing fabric yarn count, with STF addition primarily reducing the mobility of filaments and yarns in the impact zone. Microscopy shows significant energy dissipation in the damage zone that includes plastic flow of the polymeric filaments, as well as deformation of the filaments due to mechanical interaction with the colloidal particles of the STF. These results indicate that these novel materials could be used to fabricate flexible body armors that provide improved protection against stab threats.