|
Items in cart [0] |
Questions? Call 888-624-8373 |
| Copyright © 2009. National Academy of Sciences. All rights reserved. Terms of Use and Privacy Statement |
Below are the first 10 and last 10 pages of uncorrected machine-read text (when available) of this chapter, followed by the top 30 algorithmically extracted key phrases from the chapter as a whole.
Intended to provide our own search engines and external engines with highly rich, chapter-representative searchable text on the opening pages of each chapter.
Because it is UNCORRECTED material, please consider the following text as a useful but insufficient proxy for the authoritative book pages.
Do not use for reproduction, copying, pasting, or reading; exclusively for search engines.
OCR for page 20
4
Reactive Materials
INTRODUCTION
In this report, the term "reactive materials" (RMs) denotes a class of materials that
generally combine two or more nonexplosive solids which, upon their ignition, react to
release chemical energy in addition to the kinetic energy resulting when the high-speed
projectile containing the reactive materials collides with the target.) When designed into
munitions as part of the fragmentation component, reactive materials potentially have added
benefit against soft targets, providing not only destruction similar to that achieved with inert
fragments, but also energy release after penetration. The committee was briefed on aspects
of this technology by investigators and program sponsors from ONR, the Naval Surface
Warfare Center (NSWC)-Dahlgren, NSWC-IH, Eglin Air Force Base, ARDEC, Aerojet, and ATK
Thiokol Propulsion.
A reactive fragment initially delivers its energy to a very small area of a target,
perforating or penetrating the intended target. However, the reactive fragment must hit a
component of the target for the ignition of the reactive materials of the fragment and the
initiation of subsequent reactions, either with itself or with parts of the target. Experimental
firings against soft targets have shown enhanced blast damage, greatly increased
observable external rupture damage, and potentially increased lethality when compared with
conventional fragment performance.
In most operational concepts presented to the committee, the performance of the RM
fragment relies on initial penetration of the outer skin of the target, followed by impact of the
RM fragment with interior solid components of the target to ignite the reactive material.
There is also interest in and initial work underway to examine the application of reactive
M.E. Grudza, D. Jann, C. Forsyth, W. Lacy, W. Hoye, and W.E. Schaeffer. 2001. Explosive Launch
Studies for Reactive Material Fragments. Presented at the 4th Joint Classified Bombs/Warheads
and Ballistics Symposium, Newport, R.l., June.
2 J.M. Goldwasser, ONR. 2001. Presentation to the committee. July 31.
W. Hoye, NSWC-Dahigren. 2001. Presentation to the committee. October.
4 A.T. Nielsen. 2002. Presentation to the committee during its site visit to ATK Thiokol Propulsion.
May.
S. Struck. 2002. Presentation to the committee during its site visit to Eglin Air Force Base. May.
-
5
20
OCR for page 21
REACTIVE MATERIALS
21
material warheads for hard target attack by replacing standard metal liners with reactive
materials in shaped charges or explosively formed penetrators. However, this discussion
focuses on the soft target application of reactive materials. Comparisons are made between
reactive and inert fragments because of the near-term potential application of reactive
fragments as direct replacements for inert fragments in existing fragmentation warheads.
Th is com pa riven is shown i n Figu res 4-1 th rough 4 4.6 Figu re 4-1 i 11 ustrates the
damage done by inert fragments to a guidance component of a missile. Figure 4-2 shows
the greater damage caused when reactive fragments were employed against an identical
guidance component. Similarly, Figure 4-3 exhibits the results of perforation damage from
inert fragments on a missile body, and Figure 4-4 shows the effects of reactive fragments
against the same target, illustrating the catastrophic destruction of the test object.
FIGURE 4-1 Damage done by inert fragments
to the guidance component of a missile.
row
~ :~"
~ . I
~ \\——_— 1
_ 1
FIGURE 4-2 Damage done by reactive
fragments to a guidance component identical
to that shown in Figure 4-1.
FIGURE 4-3 Damage done to a missile body
by a warhead's inert fragments.
_ . ~
~ ._ .
it,,
~ ~ _
W. '~ ~:~
~ _
. ~ . ~
-, y
i,'' , <
.
~ .,
,_ . . ~ ~ .,.+, .
I; -`
~ , ~
· `~w^_L_
. ~ ~_.c_
~~ .
_ , . ,
~ ~ .
. . by, - .
FIGURE 4-4 Damage done to the same
target shown in Figure 4-3 by a warhead's
reactive fragments.
6 Figures 4-1 through 4-4 come from W. Hoyels (ONR) August 25, 2001, presentation to the
committee.
OCR for page 22
22
ADVANCED ENERGETIC MATERIALS
Reactive materials can potentially damage targets by means of numerous
mechanisms that may have cumulative effects:
Perforation-increased internal temperature from the chemical reaction of the
reactive material fragment,
Explosion-induced shock/blast waves with enhanced impulse within the target,
Overpressure,
Carbon shorting of electronic components, and
Reaction with and degradation of critical components.
If the cumulative damage caused by the reactive fragments is great enough, the
likelihood of immediately discernible kills is increased. Often, when a target is disabled by a
conventional fragment, the exterior and structural damage may be limited, making it difficult
to ascertain the result of an attack and prompting further attacks on what may be a
neutralized target. A goal of reactive fragment development programs is to cause visually
ascertainable damage resulting in improved damage assessment by standard means.
Increased lethality is projected to arise from the use of reactive fragments because of
a greater probability that sufficient damage will be done to a target with a smaller number of
fragments and because there is a greater probability that a critical part of the target will be
damaged by the secondary (chemical) reaction of the fragment within the target. The
quantification of increased lethality is difficult owing to a number of uncertainties:
Lack of confidence in the ignition of the reactive fragments;
Questions regarding the energy transferred from a material of lower density than
steel,
Uncertainty about the overall probabilities of impacting the target, and
Lack of knowledge about the physical integrity of the reactive fragments during
launch.
Energy release from reactive materials is potentially tunable, and other applications,
such as reactive casings, shaped charge liners, and explosively formed penetrators, are
envisioned. Moreover, a number of reactive systems are potentially useful. Those under
consideration include thermites, intermetallics, metal-polymer mixtures, metastable
intermolecular composites (MlCs), matrix materials, and hydrides.
FINDINGS AND RECOMMENDATIONS
Findings
With regard to reactive materials, the committee found that—
.
.
· Reactive materials research and characterization are in an early state of exploration
and development.
Most experimental demonstrations of weapon effects from reactive materials have
shown more extensive, externally visible target damage when compared with
damage caused by inert fragments under similar conditions.
Higher peak pressures and a detonation-like reaction were achieved in experiments
with RM-4. The results in these cases were dramatic.7
I
R.G. Ames, R.K. Garrett, and L. Brown. 2002. Detonation-like Energy Release from High-Speed
Impacts of Polytetrafluoroethylene-Aluminum Projectiles. Presentation at 5th Joint Classified
Bombs/ Warheads and Ballistics Symposium, Colorado Springs, June.
OCR for page 23
REACTIVE MATERIALS
23
Recommendations
Research on reactive materials is very promising in terms of potential near-term payoff.
The research may also have potentially longer-term, broader-based application. The
committee recommends the following:
Many trade-off studies should be conducted before reactive materials can move
forward.
The possibility of more advanced applications (such as liners and cases) should be
explored.
Appropriate analytical tools should be developed and used, along with critical
experiments, to determine applicability.
Other materials such as thermoplastics should be investigated in greater detail with
lower processing temperatures to allow the use of other metals.
Requirements regardingthe material properties of reactive materials should be
correlated with results in realistic warhead tests including probability of kill.
Greater emphasis should be given to materials engineering research and
deployment methods to improve the lethality of reactive materials against both soft
and hard targets.
Representative terms from entire chapter:
reactive fragments
