Ballistic Properties of Zylon for Application to Firearm 

Projectile Protection 

by E. Pineda, C. Hogue, and W. Goldsmith 

ARL-CR-529 July 2003 

prepared by 

Department of Mechanical Engineering 

University of California, Berkeley 

Berkeley, CA 94720 

in cooperation with 

SRI International 

333 Ravenswood Ave. 

Menlo Park, CA 94025 

under contract 

DAAD17-01-P-0888 

Approved for public release; distribution is unlimited.
NOTICES 

Disclaimers 

The findings in this report are not to be construed as an official Department of the Army position unless 

so designated by other authorized documents. 

Citation of manufacturer’s or trade names does not constitute an official endorsement or approval of the 

use thereof. 

Destroy this report when it is no longer needed. Do not return it to the originator. 
Army Research Laboratory 

Aberdeen Proving Ground, MD 21005-5066 

ARL-CR-529 July 2003 

Ballistic Properties of Zylon for Application to Firearm 

Projectile Protection 

E. Pineda, C. Hogue, and W. Goldsmith 

prepared by 

Department of Mechanical Engineering 

University of California, Berkeley 

Berkeley, CA 94720 

in cooperation with 

SRI International 

333 Ravenswood Ave. 

Menlo Park, CA 94025 

under contract 

DAAD17-01-P-0888 

Approved for public release; distribution is unlimited. 
ii

Abstract 

In recent years, a para-phenylene benzobisoxazole fiber, Zylon (registered trademark of the 

Toyobo Company), has surfaced as a potential candidate for body armor to possibly replace 

Kevlar (registered trademark of DuPont). Zylon’s effectiveness depends on its ballistic 

properties as well as its mass in comparison with Kevlar. The present extended investigation 

focuses on determining the ballistic limit and the V50 velocity for 10, 20, and 30 stitched plies of 

Zylon using standard North Atlantic Treaty Organization 9-mm nonrotating strikers. This report 

concentrates specifically on the ballistic limit of 10-ply Zylon, as well as the effect that impact 

location has on perforation. It was also discovered that many other factors affect the ballistic 

performance, including slip of the fabric in the holder, the preparation of the shell, and the 

amount of fiber damage present. These aspects will be considered when evaluating Zylon’s 

performance and determining whether or not it is indeed superior to Kevlar for applications in 

body armor and personnel protection. The first instance of perforation for 10-ply Zylon occurred 

at an initial velocity of 341.4 m/s, and the highest initial velocity for a ricochet was 566.2 m/s. 
iii

Contents 

List of Figures v

List of Tables v

1. Introduction 1

2. Objectives 1

3. Experimental Setup 2

4. Procedure 5

5. Results and Discussion 6

5.1 Sources of Error...............................................................................................................6 

5.2 Load-Deformation Tests..................................................................................................7 

6. Ballistic Tests 7

7. Conclusions 13

8. References 14

Report Documentation Page 15
iv

INTENTIONALLY LEFT BLANK. 
v

List of Figures 

Figure 1. The aluminum target holder clamped to the steel backstop. ...........................................2 

Figure 2. The 0.50-cal. powder gun: (a) side view and (b) rear view............................................3 

Figure 3. Timing grid holders: (a) 3/4 view from ~2 m and (b) top view, close-up......................4 

Figure 4. Rebound catcher box. ......................................................................................................4 

Figure 5. Zylon target (note: 20-ply sheet shown).........................................................................5 

Figure 6. Typical target deformation of a near-perforating shot. ...................................................7 

Figure 7. Load displacement curves. ..............................................................................................8 

Figure 8. Final vs. initial velocity. ..................................................................................................8 

Figure 9. Final vs. initial velocity (striking velocity). ..................................................................11 

Figure 10. Recovered projectiles (note: numbers beneath projectiles indicate initial velocity 

in meters per second). ..............................................................................................................12 

List of Tables 

Table 1. Tabular ballistic data.........................................................................................................9 
vi

INTENTIONALLY LEFT BLANK. 
1

1. Introduction 

Zylon* is a para-phenylene benzobisoxazole (PBO) fiber made by the Toyobo Company of 

Osaka, Japan, with promise to replace today’s aramids as the super high-performance fiber of the 

future. It is far superior to Kevlar† and other aramids in both mechanical properties and 

resistance to such environmental effects as heat, moisture, abrasion, and seawater corrosion. 

Because of these properties, the U.S. Army took an interest in Zylon as a future bulletproof 

material. Based on a contract from the Army, the goal of this project is to determine the ballistic 

performance of Zylon. This is summarized into two basic experimental results—the ballistic 

limit and the limit velocity. 

The earliest reference to “modern” body armor located by a literature search consisted of a 1931 

photograph of a bulletproof vest that was not published until 1988 [1]. Other references 

involving personnel protection have appeared primarily during the last decade [e.g., 2–6] and 

have been almost exclusively concerned with ballistic fabric or fabric composite shielding. 

Widespread investigations of projectile penetration and perforation for normal impact have been 

presented in references [7, 8] and for nonstandard impact conditions, in reference [8]. The 

ballistic limit can be improved in many ways, both through advances in materials and in the 

geometry of their application. This study involves simply testing a new material, Zylon, for 

comparison against similar ballistic fabrics such as Kevlar. New applications for Zylon are 

being investigated, including a joint project between Boeing, SRI, the Federal Aviation 

Administration, and the University of California, Berkeley, to explore containment barriers on 

commercial aircraft jet engines. Their function would be to protect vital fuselage components 

and systems, as well as passengers, from high velocity fan fragments that can result from 

catastrophic engine failure. 

2. Objectives 

The ballistic limit represents the speed of a nonrotating striker of given mass and dimensions at 

which half of the projectiles will just perforate a specified target at normal incidence [9]. The 

V50 and limiting velocity is a somewhat more complicated mathematical function and requires a 

program to compute. These calculations will be made for the samples of 10-, 20-, and 30-ply 

Zylon targets. In addition to these concrete objectives, other consequential concerns arose after 

the initial stages of experimentation. First, it was discovered that the boundary conditions of the 

Zylon target had a great affect on the performance of the fabric. Not only the velocity of the 

 *

 Zylon is a registered trademark of the Toyobo Company. 

†

 Kevlar is a registered trademark of DuPont. 
2

projectile, but also the location of the impact (relative to the edges of the target holder) became 

important. This phenomenon is clearly rooted in the “give” of the material farther from its rigid 

boundaries. The results of a static force deflection test at various locations on the target will be 

discussed later. At this point, the effects are only qualitative, but there is hope of developing a 

model (based on the boundary conditions of a thin membrane with a distributed load) to make 

this conclusion more quantitative. Also, due to the thickness of the target samples, there was 

slipping of the material within the holder at high/nonperforating shots. Some of this should be 

eliminated after some modifications to the target holder (see section 5). 

3. Experimental Setup 

The experimental setup included a 14- × 14-in aluminum target holder, C-clamped at four 

corners to a steel “backstop” (Figure 1) that was, in turn, secured to a 680-kg steel table on which 

the gun was mounted. 

Figure 1. The aluminum target holder clamped to the steel backstop. 

The targets were struck relatively centrally and normally by standard 9-mm full metal jacket 

flatback handgun projectiles, made by either Remington or Winchester. The projectiles had a 

nominal diameter of 0.355 in and a length of 0.625 in. They were made of lead, with a thin 

copper alloy jacket, and had an average mass of 124 gr each and a sectional density of 0.141. 

The 9-mm projectiles were saboted for a 0.50-cal. powder gun. The 0.50-cal. powder gun 

(Figure 2) consisted of a 20-mm-thick high-strength steel barrel with an inside diameter of 0.501 

in and a length of 1.6 m, a breech capable of accommodating a 50-mm cartridge and a supporting 

rail frame which attached the unit to the support. 
3

 

Figure 2. The 0.50-cal. powder gun: (a) side view and (b) rear view. 

The initial velocity of the projectiles was measured by the duration required to break the beams 

of two parallel helium-neon lasers positioned directly in front of the muzzle, separated by 

165 mm, with the first of the two lasers located 24 in from the gun muzzle. The target itself was 

~44 in from the muzzle. The lasers were focused on two custom photodiodes generating a 

voltage pulse recorded by a Hewlett-Packard 5316 time-interval counter. The final velocity of 

the fastest object behind the target was determined by the time between the signals generated by 

two aluminum foil make screens, each about 432 × 254 mm in size, and separated by 155 mm. 

The two aluminum foil sheets constituting a make screen were separated by a distance of 6 mm. 

The two make screens generated both a starting and stopping pulse recorded by a second time 

interval meter from which the final velocity was determined. 

A second “backup” system of consecutive paper targets with a grid of interlocking conducting 

ink lines (Figure 3) worked in a similar fashion to the foil, also making use of a second HewlettPackard 5316 time-interval counter. 

A blast shield was placed 10 inches in front of the gun muzzle to prevent undue damage to the 

rebound catcher box and to keep gasses and firing debris from interacting with data-collecting 

equipment. The rebound catcher box (Figure 4) was essentially a foam cage with an entrance 

hole for the projectile and small holes in the sides for the initial velocity lasers to pass through to 

the detectors. A catcher box using rags was placed behind the gun table to soft recover 

projectiles and plugs. Several blocks of buff potters clay were placed in front of this catcher box 

to further slow perforating projectiles. 

(a) (b) 
4

 

Figure 3. Timing grid holders: (a) 3/4 view from ~2 m and (b) top view, close-up. 

Figure 4. Rebound catcher box. 

(a) (b) 
5

4. Procedure 

The 12- × 12-in Zylon target sample (Figure 5) was secured in an aluminum target holder with 

essentially a machined “tongue and groove” system to minimize fabric slipping. Uniformity is 

achieved through the use of an 85 in-lb torque wrench at the numerous screws around the target 

holder. The targets themselves are 10-, 20-, and 30-ply sheets of Zylon sewn together with 

chain-link fence-type crisscross stitching. For the thicker samples, the tapped holes will be bored 

out, and stronger tool-grade steel bolts will be used in lieu of the less reliable lag screws. The 

desired impact location was aligned to the bore by a laser placed in the breech. The position of 

the impact was recorded to investigate effects of different tensile preloads in the Zylon target. 

Figure 5. Zylon target (note: 20-ply sheet shown). 

The lasers and photodiodes were turned on to record the initial velocity of the striker upon beam 

interruption. Two aluminum foil make switches, each consisting of a set of closely spaced 

parallel sheets, were connected to a time-interval meter that measured the time differential of the 

passage between the two positions, representing the final velocity of the projectile behind the 

target. 
6

Following a test, the projectile was recovered. In a few instances, the projectile shattered, most 

likely from contact with metallic objects other than the target (e.g., the back of the steel catcher 

box), and, in other cases, it could not be recovered due to single or multiple ricochet, especially 

when deviating from its initial trajectory due to impact. The position of the holes in the foils was 

examined to ascertain the projectile trajectory. 

5. Results and Discussion 

5.1 Sources of Error 

There are many factors that contribute to the accuracy of our data; all must be taken into account 

when observing the data. First and foremost are the boundary conditions of the target holder. 

The closer to an edge or corner the projectile strikes, the easier it is for the projectile to perforate. 

With multiple shots per target, it is impossible to have all shots in the center. Another concern 

when firing multiple shots per target is whether or not the strength of the target as a whole is 

compromised after the first shot. Figure 6 shows the typical target deformation (originally taut) 

from a near-perforating target-center shot. If a shot hits too close to a previous impact, the 

projectile may strike fibers damaged from a previous shot. It is obvious that if this is the case, 

the data obtained will not be accurate. 

The way that the target is secured in the holder also affects the outcome of shots. The target slips 

slightly from the “grasp” of the target holder upon impact, which increases the targets resistance 

to perforations. The amount the target slips ranges from 1/2 to 1 in. Previously, the target holder 

used 16 tapped holes with bolts torqued to a maximum of 85 in-lb to secure the target. Any 

torque higher than 85 in-lb would snap the bolts. Also, after a few months, the threads of the 

holes began to wear. This created a resistance to the torque applied in the bolts which made it 

difficult to assess the actual torque in each bolt. The target holder has been modified to a nut and 

bolt design, which allows for more torque to be applied to each bolt, and there is no resistance 

from threads. Soon, higher-grade, larger diameter (3/8 in rather than 1/4 in) bolts will be used, 

allowing for even more torque. 

The way that a shell is loaded can also have a great impact on the projectile’s initial velocity. 

Due to the size of the projectiles, slight variations in the amount of wadding or the way it is 

tamped down in the shell can greatly affect velocity. It is difficult to obtain desired velocities, 

and thus difficult to get data for specific areas of interest. This proves to be quite a nuisance 

when specific velocities are needed to find the V50 or the ballistic limit. It becomes a “shootingin-the-dark” process, which increases the number of targets needed to obtain specific data. 
7

Figure 6. Typical target deformation of a 

near-perforating shot. 

5.2 Load-Deformation Tests 

Due to the implication that the location of impact (with respect to the boundary of the target 

holder) may greatly affect the chance of perforation, load-deformation tests were performed on a 

10-ply sheet of Zylon while it was secured in the target holder. Each of the 16 screws was 

torqued up to 85 in-lb. Figure 7 shows these tests that were performed at three locations—2.5 in, 

4.5 in along the diagonal, and in the center. 

It was found that the closer to the center of the target one gets, the less force is required to 

elastically deform the material. Therefore, shots fired closer to the corners have a greater chance 

of perforating because less energy is absorbed by the target. This fact greatly affects our ballistic 

results. It was also found that when a target is fired, it slips in the target holder. Due to this 

implication, we changed the target holder to accommodate a nut and bolt setup with high-grade 

bolts. 

6. Ballistic Tests 

Fifty-four shots were fired at various points on 10-ply sheets of Zylon. The complete results for 

all the shots, obtained from the data in Table 1, are shown in Figure 8. However, since the 

location of the shots, as well as many other factors, affects the projectile’s ability to perforate, 

Figure 8 is not a completely accurate depiction of the ballistic capabilities of Zylon. However, 
8

Figure 7. Load displacement curves. 

Figure 8. Final vs. initial velocity. 

corner shots can be considered a lower bound of sorts and the center shots an upper bound. 

These discrepancies can be clearly seen using Figure 8. For instance, there is a nonperforating 

shot with an initial velocity of 566 m/s fired at the center as well as a perforating shot at 349 m/s 

fired near the corner. Finally, Figure 9 is a three-dimensional plot of initial velocity of 

projectiles vs. the striking location on the target measured from an origin at an arbitrary corner of 

the target. 

Load vs. Displacement for 10-ply Zylon

-400

-350

-300

-250

-200

-150

-100

-50

0

50

-30 -25 -20 -15 -10 -5 0 5

Displacement (mm)

Load (N)

Position 1: 2.5" from the

corner

Position 2: 4.5" from the

corner

Position 2: center

Final vs. Initial Velocity for 10 Plies of Zylon

0

50

100

150

200

250

300

350

400

450

500

0 100 200 300 400 500 600 700 800 900 1000

Initial Velocity (m/s)

Final Velocity (m/s)
9

Table 1. Tabular ballistic data. 

Shot No. Ply 

Powder 

Load 

(g) 

Initial 

Velocity 

(m/s) 

Final 

Velocity

(m/s) 

Type of

Bullet Perforation? X Position

(in) 

Y Position 

(in) 

Comments

1 10 5.2 error NA R N 3.25 9 

2 10 5.81 348.9 309.5 R Y 7 8.25 

3 10 6 error 508.86 R Y 4 4 

4 10 6 890.4 440.5 R Y 7.5 4.5 

5 10 6 320.5 error R Y 6.375 8.125 

Shot fired 

without 

sabot 

stripper. 

6 10 6 783.5 471.8 R Y 5.25 3.5 

Shot fired 

without 

sabot 

stripper. 

7 10 6.5 598.7 error R Y 4.5 4.75 

Sabot was 

not stripped.

8 10 6.5 513.4 458.2 R Y 3.25 3.75 

9 10 7 error 457.8 R Y 5 3.75 

10 10 7 error error R Y 8.125 4.5 

11 10 7 591.2 error R Y 9.75 7.25 

12 10 7.5 395.3 105 R Y 6.375 7.5 

13 10 7.5 1757.2 error R Y 3.5 7.875 

14 10 8 error 236.6 R Y 3.875 6.25 

15 10 5 682.4 error R Y 7.875 6.75 

16 10 0.5 91.63 NA R N 8.25 4.75 

17 10 0.75 error NA R N 6 6.125 

18 10 0.75 81.45 NA R N 3.25 4.125 

19 10 1 27.3 NA R N 6.125 8.375 

20 10 1 88.33 NA R N 3 7.5 

21 10 1.25 175.53 NA R N 5.625 4.25 

22 10 1.5 19.55 NA R N 8 8.75 

23 10 1.75 error NA R N 7.75 6.375 

24 10 1.75 118 NA R N 4 3.75 

25 10 6 924.89 440.22 R Y 7.25 5.75 

26 10 0.5 error NA W N 4.375 4.875 

27 10 0.5 56.99 NA W N 7.75 7.25 

28 10 0.75 99.4 NA W N 6.875 6.125 

29 10 1 108.4 NA W N 4.75 8 

30 10 1.25 167.67 NA W N 4.125 4.5 

31 10 2 130 NA R N 2.75 8.875 

32 10 2.5 137.5 NA R N 7.625 3.75 

33 10 3 error NA R N 5.75 6.125 

34 10 3.5 354.3 NA R N 2.5 4.25 

35 10 1.5 error NA W N 5.5 NA 
10

Table 1. Tabular ballistic data (continued). 

Some interesting information was gained from the recovered projectiles themselves. Figure 10a 

shows some typical low-velocity, nonperforating projectiles (57–138 m/s) that suffered almost 

no visible damage upon impact. However, it is also known that each of these projectiles rotated 

upon impact with the Zylon target and was finally brought to rest completely sideways. This 

was inferred from the imprint of the bullet left on the Zylon, clearly showing the bullet-like 

profile of the projectile, rather than a circular one. The extreme case of this rotation can be seen 

in Figure 10b. Here, higher velocity nonperforating projectiles (161–451 m/s) showed 

significant deformation in the lateral direction from being “squished” sideways against the Zylon 

target upon rotation. (Note: The bullets in Figure 10b are shown from behind, parallel to their 

major axes.) This rotation appears to help the target absorb energy, thus allowing no perforation 

at 451 m/s, even though lower velocity projectiles showed perforation (such as the 321- and 

349-m/s projectile in Figure 10d). Compare these laterally deformed projectiles to those in 

Figure 10c. Here, the projectiles did not rotate upon impact, and they bear the more intuitive 

Shot No. Ply 

Powder 

Load 

(g) 

Initial 

Velocity 

(m/s) 

Final 

Velocity

(m/s) 

Type of

Bullet Perforation? X Position

(in) 

Y Position 

(in) 

Comments 

36 10 1.5 260.6 NA W N 2.5 3 

Sabot was not 

stripped. 

37 10 2.5 229.26 NA W N 4 8.25 

38 10 2 169.3 NA W N 4 8.125 

39 10 3 161.29 NA W N 8.25 7.5 

40 10 3.5 310 NA W N 4.375 5.5 

41 10 4 497.4 NA R N 8.375 4.125 

Bullet hit target 

holder before 

striking target. 

42 10 4 243.5 NA R N 6.875 4.5 

43 10 4.5 451.44 4.5 R N 4.875 6.25 

44 10 5 342.89 error R Y 3.5 6.375 

45 10 3 344.9 NA R N 5.25 4.25 

46 10 3.5 203.5 NA R N 3.625 5 

Sabot was not 

stripped. 

47 10 4 error error R error NA NA 

48 10 3.5 566.2 NA R N 5 6.5 

49 10 3.6 399.8 NA R N 5.75 6.25 

50 10 3.7 error error R error NA NA 

51 10 4.1 250 NA R N 5.5 5 

Initial velocity 

obtained from 

high-speed video 

camera. 

52 10 4.2 341.4 313.6 R Y 5.5 5.75 

53 10 4 177.4 NA R N 6.125 6 

54 10 4 271.1 NA R N 5.5 6 
Initial Velocity vs. Postion for 10 Ply Zylon

Red asterisk are penetration shots ^, - ^''

2000

-^1500

-_

>-.

I 1000

>

= 500

4-

j-'

j-'' #

.^'^y .

Blue dots are no penetration

shots

+

-Position(in) 2 2

X-Positionfin)

Figure 9. Final vs. initial velocity (striking velocity).

"snub-nosed" shape expected from fully anterior deceleration. Finally, Figure lOd shows some

typical perforating shots with velocities ranging from 321 to 890 m/s. It is interesting to note

that the higher velocity perforating shots show less damage than those that perforated at lower

velocity.

The Vsowas estimated using the following:

Vso = V*(ao + a,X + a2X' + a^x' + a4X'), (1)

where X = AdAp/mp = (fabric areal density)(projectile base area)/(projectile mass),

Ad = 1.56 kgW, Ap = 254.5 x lO'^gW, mp - 0.00803 kg, and ao = 0.323, a, = 6.732,

a2 = -26.642, aj = 68.442, a4 = -62.446, and V* = 813.2 [10].

V50 was calculated to be 486.8 m/s. Our first instance of perforation was at 341.4 m/s, and our

last instance of no perforation was at an initial velocity of 566.2 m/s. Both of these shots were

center shots, but the former shot was fired after the nut and bolt fasteners were implemented in

the target holder. This allowed for a reduction in slip, thus allowing the target to absorb less of

11
12

Figure 10. Recovered projectiles (note: numbers beneath projectiles indicate initial velocity 

in meters per second). 

(a) 

(b) 

(c) 

(d) 
13

the projectile’s kinetic energy, resulting in a perforation. These variances in actual limits from 

the theoretical limit can be attributed to the location of the shots, the accuracy of the initial 

velocity equipment, and slipping in the target holder. None of these factors can be completely 

eliminated. Multiple shots per target are necessary due to the number of targets available. The 

slip can be reduced in our target holder, but it can never be zero. With the data provided in this 

report, the ballistic limit for various impact locations can be determined. However, the ballistic 

limit is not the same as the V50 or the limiting velocity. The V50 as well as the limiting velocity 

will be found on a later date using the programs provided. 

The average 9-mm handgun has a muzzle velocity of 388 m/s [11]. Ten plies of Zylon are not 

enough to stop a shot from the average 9-mm handgun, but a slight increase in the number of 

plies should prove effective. Ten plies of Kevlar 29 have a V50 of 434 m/s [12]. Although 

Kevlar 29 has a higher V50 than Zylon, Zylon has a lower areal density. Ten plies of Zylon have 

an areal density at 1.56 kg/m2

, and 10 plies of Kevlar 29 have an areal density of 2.95 kg/m2 [12]. 

Therefore, it may take more plies of Zylon than Kevlar 29 to stop a projectile, but with Zylon’s 

significantly lower areal density, that amount of plies will weigh less than the ballistic equivalent 

made of Kevlar 29. This shows that Zylon would be more practical than Kevlar 29 for use as 

body armor in the military and law enforcement where mass is critical. 

7. Conclusions 

Ten plies of Zylon were not enough to stop a 9-mm bullet fired from an average handgun, nor 

was the theoretical V50 or the ballistic limit higher than that of Kevlar 29. However, a slight 

increase in plies should be enough to overcome both of these. Since Zylon has a far less areal 

density than Kevlar 29, the mass of the number of plies needed to reach the ballistic limit of 

Kevlar would still be less than that of 10 plies of Kevlar. Twenty plies of Zylon, which will be 

tested next, should prove effective against projectiles fired at 388 m/s. 

Despite the sources of error, a ballistic curve was obtained. The error that comes from the target 

and the target holder can be considered positive because Zylon in real-world use will not be in 

laboratory conditions. For 20 plies of Zylon, the slip will be minimized due to modifications 

made on the target holder. It is essential that the fabric holds up no matter what adversities it 

faces—multiple shots, slipping, or any other nonideal conditions. 

Zylon is the “ballistic fabric” of the future. Zylon’s low areal density allows for more 

maneuverability and proves to be more practical for applications in the armed forces and law 

enforcement than Kevlar. Further testing will show the number of plies of Zylon needed to 

achieve the same ballistic limit, as Kevlar 29, will weigh less. 
14

8. References 

1. Patton, A. “Images of the Past—‘Who Cares About Bullets.’ ” American History, vol. 33, 

no. 1, 1988. 

2. Anderson, K. J. “Ceramic-Metal Composite—Bulletproof Strength.” Mechanical 

Engineering, vol. 112, no. 7, pp. 46–51, 1990. 

3. Roberts, G. K., and M. E. Bullian. “Protective Ability of the United States Military Personal 

Armor System, Ground Troops (PAGT): Fragmentation Vest Against Common Small Arms 

Projectiles.” Military Medicine, vol. 158, pp. 560–563, 1993. 

4. Bazhenov, S. “Dissipation of Energy by Bulletproof Aramid Fabric.” Journal of Materials 

Science, vol. 32, pp. 4167–4173, 1997. 

5. Scott, B. “Bullet-Resistant Vests: Dressed to the Nine Millimeters.” Scientific Americana, 

vol. 176, p. 132, 1997. 

6. Ashley, S. “Aramid-Fiber Reinforced Nylon.” Mechanical Engineering, vol. 119, p. 30, 

1997. 

7. Corbett, G. G., S. R. Reid, and W. Johnson. “Impact Loading of Plates and Shells by FreeFlying Projectiles: A Review.” International Journal of Impact Engineering, vol. 18, 

pp. 141–230, 1996.

8. Goldsmith, W. “Non-Ideal Projectile Impact on Targets.” International Journal of Impact 

Engineering, vol. 22, pp. 95–395, 1999. 

9. Cipparone, G., B. Bourne, D. Orphal, and W. Goldsmith. “Momentum Exchange Alteration 

in Projectile/Target Impact.” International Journal of Impact Engineering, vol. 27, pp. 691–

707, 2000. 

10. Orphal, D. Personal communication with E. Pineda. February 2002. 

11. Koeing, B., S. Hoffman, N. Hirotaka, and S. Beck. “Signal Convolution of Recorded Free 

Field Gunshot Sounds.” Journal of Audio Engineering, vol. 46, pp. 7, 8, and 638, 1998. 

12. Cunniff, P. M. “The Performance of Poly(Para-phenylene benzobisoxazole) (PBO) Fabric 

for Fragmentation Protective Body Armor.” 18th International Symposium on Ballistics, 

vol. 2, pp. 837–844, 1999.
15

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1. REPORT DATE (DD-MM-YYYY)

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2. REPORT TYPE 

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3. DATES COVERED (From - To) 

August 2001–April 2002 

5a. CONTRACT NUMBER 

DAAD17-01-P-0888 

5b. GRANT NUMBER 

4. TITLE AND SUBTITLE 

Ballistic Properties of Zylon for Application to Firearm Projectile Protection

5c. PROGRAM ELEMENT NUMBER 

5d. PROJECT NUMBER 

PERS01 

5e. TASK NUMBER 

6. AUTHOR(S) 

E. Pineda, C. Hogue, and W. Goldsmith

5f. WORK UNIT NUMBER 

7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) 

Department of Mechanical Engineering SRI International 

University of California, Berkeley 333 Ravenswood Ave. 

Berkeley, CA 94720 Menlo Park, CA 94025

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U.S. Army Research Laboratory 

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11. SPONSOR/MONITOR'S REPORT 

 NUMBER(S) 

ARL-CR-529 

12. DISTRIBUTION/AVAILABILITY STATEMENT 

Approved for public release; distribution is unlimited.

13. SUPPLEMENTARY NOTES 

Point of contact for this report is Dr. Nevin Rupert, U.S. Army Research Laboratory, ATTN: AMSRL-WM-TD, Aberdeen 

Proving Ground, MD 21005-5066.

14. ABSTRACT 

In recent years, a para-phenylene benzobisoxazole fiber, Zylon (registered trademark of the Toyobo Company) has surfaced as a 

potential candidate for body armor to possibly replace Kevlar (registered trademark of DuPont). Zylon's effectiveness depends 

on its ballistic properties as well as its mass in comparison with Kevlar. The present extended investigation focuses on 

determining the ballistic limit and the V50 velocity for 10, 20, and 30 stitched plies of Zylon using standard North Atlantic 

Treaty Organization 9-mm nonrotating strikers. This report concentrates specifically on the ballistic limit of 10-ply Zylon, as 

well as the effect that impact location has on perforation. It was also discovered that many other factors affect the ballistic 

performance, including slip of the fabric in the holder, the preparation of the shell, and the amount of fiber damage present. 

These aspects will be considered when evaluating Zylon's performance and determining whether or not it is indeed superior to 

Kevlar for applications in body armor and personnel protection. The first instance of perforation for 10-ply Zylon occurred at an 

initial velocity of 341.4 m/s, and the highest initial velocity for a ricochet was 566.2 m/s. 

15. SUBJECT TERMS

Zylon, body armor, ballistics, ballistic testing

16. SECURITY CLASSIFICATION OF: 

19a. NAME OF RESPONSIBLE PERSON

Nevin Rupert 

a. REPORT 

UNCLASSIFIED 

b. ABSTRACT 

UNCLASSIFIED

c. THIS PAGE 

UNCLASSIFIED

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OF ABSTRACT 

UL 

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(410) 278-9652 

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