This study examined the ballistic response of various shear thickening fluids (STFs) to projectile impacts. STFs are non-Newtonian fluids whose viscosity increases dramatically with increasing shear rates. The authors tested 5 STF mixtures made from silica and silicon carbide particles suspended in a carrier fluid. A single-stage gas gun fired projectiles at velocities from 300-800 m/s into test samples contained in Mylar disks. High-speed video was used to measure projectile velocity changes. At lower velocities, the most shear thickening fluid (66.7% silica) produced the greatest velocity reduction. At higher velocities, fluid density had a greater influence on performance. STFs showed potential for improving body

1. • A shear thickening fluid (STF) is a non-
Newtonian fluid whose viscosity increases under
increasing shear rates (see Figure 1).
• Under low shear rates, a STF provides little
resistance to motion, whereas at higher shear
rates the fluid can have an infinite viscosity,
similar to a solid
• Integration of shear thickening fluids into Kevlar
fabrics to create lighter, less constraining, and
more effective body armor [1]
• Shear thickening fluids are currently built-into
some sporting equipment (D3O Labs)
• The impregnation of STFs in ballistic fabrics has
shown promise in increasing the stab protection
offered by the fabrics [2].
Compare the ballistic response of various particle
suspensions based on their:
• Rheological properties
• Density
• Suspended particles
• Projectile was a NATO standard 17 grain (1.1g)
Fragment Simulating Projectile
• Initial projectile velocity ranged from 300m/s to
800m/s
• The velocity of the projectile was measured on
entrance and exit of the test sample.
• Measurements were made using a high-speed
camera at 13,000 frames per second
• Mylar disks used to contain test fluid and allowed
easy penetration of the projectile, shown to not
influence the experimental results.
• At the lower projectile velocities, the 66.7% SiO2
mixture, the most readily shear thickening fluid
tested, resulted in the greatest change in velocity
of the projectile, despite its lower density than
many other fluids tested. This demonstrated the
dominating effect of shear thickening at lower
impact velocities.
• At high projectile velocities, fluid density became
the dominating factor in the ballistic response of
the fluids.
The authors would like to thank Simon Ouellet and
Jacques Blais of Defence Research and Development
Canada-Valcartier for their support and collaboration
on this project
[1] Y.S. Lee, E.D. Wetzel, and N.J. Wagner (2003), J.
Mat. Sci., 38(13):2825-2833
[2] D.P. Kalman, R.L. Merrill, N.J. Wagner, and E.D.
Wetzel (2009), Appl. Mat. & Int. 1(11):2602-2612
Ballistic Response of Shear Thickening Fluids
Bradley J. Marr, Oren E. Petel, and David L. Frost
McGill University, Montréal, Québec, CANADA
Introduction
Objectives
Current Applications
Experimental Details
Single Stage Gas Gun
Test Section
Results Results
Discussion
0
100
200
300
400
500
600
1 1.2 1.4 1.6 1.8 2 2.2
ChangeinVelocity(m/s)
Mixture Density (g/cc)
Vin~350m/s
Vin~560m/s
Vin~700m/s
Vin~800m/s
0
100
200
300
400
500
600
0 10 20 30 40 50 60 70 80
ChangeinVelocity(m/s)
Solid Particle Volume Fraction
Vin~350m/s
Vin~560m/s
Vin~700m/s
Vin~800m/s
0
100
200
300
400
500
600
300 400 500 600 700 800 900
ChangeinVelocity(m/s)
Projectile Velocity (m/s)
24.1% SiC (ρ=1.62)
41.0% SiC (ρ=1.98)
48.0% SiC (ρ=2.12)
48.0% SiO2 (ρ=1.44)
66.7% SiO2 (ρ=1.62)
Fluid Samples
Mixture
Suspended
Solid
Volume Fraction
of Solid Phase
Density of
Mixture
1 SiC 24.1 1.62
2 SiC 41.0 1.98
3 SiC 48.0 2.12
4 SiO2 48.0 1.44
5 SiO2 66.7 1.62
Figure 5. Response of fluid to ballistic impact in terms of (a) Fluid
Density (b) Solid Particle Volume Fraction (c) Fluid Composition.
Figure 6. Response of 66.7% SiO2 test sample at initial projectile
velocities of (a ) 359 m/s; note how little fluid is leaving the test
section following the projectile penetration, demonstrating the shear
thickening nature of the fluid, (b) 560m/s.
Figure 9. Response of 48% SiC test sample at initial projectile
velocities of (a) 356 m/s (b) 567m/s.
Figure 8. Response of 41% SiC test sample at initial projectile
velocities of (a) 350 m/s (b) 560m/s.(a)
(b)
(c)
Figure 3. Rendered schematic view of the test section used to
contain the fluid samples.
Figure 1. Shear stress-shear rate relation amongst various groups of
fluids.
ReferencesFigure 4. Density and composition properties of the five fluids used
during experimentation
Acknowledgements
Figure 7. Response of 24.11% SiC test sample at initial projectile
velocities of (a) 348 m/s (b) 563m/s.
(a)
(b)
(a)
(b)
(a)
(b)
(a)
(b)
Figure 2. D3O Olympic ski suit
containing STF technology
Path of
Projectile
Viscosity