U.S. patent application number 16/126108 was filed with the patent office on 2019-04-11 for dual-mode shaped charge device.
The applicant listed for this patent is Enig Associates Inc.. Invention is credited to Michael J. BARNARD, Eric N. ENIG, Fred Irvin GRACE.
Application Number | 20190107371 16/126108 |
Document ID | / |
Family ID | 65993121 |
Filed Date | 2019-04-11 |
![](/patent/app/20190107371/US20190107371A1-20190411-D00000.png)
![](/patent/app/20190107371/US20190107371A1-20190411-D00001.png)
![](/patent/app/20190107371/US20190107371A1-20190411-D00002.png)
![](/patent/app/20190107371/US20190107371A1-20190411-D00003.png)
United States Patent
Application |
20190107371 |
Kind Code |
A1 |
GRACE; Fred Irvin ; et
al. |
April 11, 2019 |
DUAL-MODE SHAPED CHARGE DEVICE
Abstract
An explosive device composed of an explosive annular shaped
charge liner having a given configuration; and an initiator
configured to detonate said liner according to a selected one of
two different jet formation modes.
Inventors: |
GRACE; Fred Irvin; (York,
PA) ; BARNARD; Michael J.; (Laurel, MD) ;
ENIG; Eric N.; (Bethesda, MD) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Enig Associates Inc. |
Bethesda |
MD |
US |
|
|
Family ID: |
65993121 |
Appl. No.: |
16/126108 |
Filed: |
September 10, 2018 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
62555757 |
Sep 8, 2017 |
|
|
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F42B 1/028 20130101;
F42B 3/22 20130101; F42B 1/02 20130101; F42B 3/11 20130101; F42C
19/0842 20130101; F42C 19/0846 20130101 |
International
Class: |
F42B 3/22 20060101
F42B003/22; F42B 1/028 20060101 F42B001/028 |
Claims
1. An explosive device comprising: an explosive annular shaped
charge liner having a given configuration; and an initiator
configured to detonate said liner according to a selected one of
two different jet formation modes.
Description
[0001] This provisional patent application describes an explosively
driven annular shaped charge liner having a unique shape together
with an initiator design to provide two different jet formation
modes from a single liner configuration. These modes include
formation of a "tubular" jet or alternatively, a "constituted" jet.
The reconstituted jet is created when the tubular jet is designed
to have significant convergence (inward radial and forward velocity
components) and upon collision with the central axis of the device.
This forms a new jet that is co-aligned with the axis as a solid
massive jet with properties similar to jets formed from a
hemispherical liner. There have been various attempts in the past
to produce tubular jets or ring projectiles by several researchers
[1, 2, 3]. For example, Glass, Kronman, and Golaski [1] at the
Ballistic Research Laboratory in 1969, reported work on an annular
charge with a conical cross section to form a "cookie cutter" jet.
Results indicated that tubular jets could be formed but these had
some divergence and poor standoff performance. As far as is known,
there have been no attempts to form a solid jet on-axis from the
motion of a previously formed jet (converging conical shaped jet).
In this regard, the reconstituted jet formation presented herein
represents a new jetting mechanism.
[0002] [ML1]
[0003] The weapons community has a long-standing commitment to
pursuit of advanced shaped charge designs as well as experimental
and analytical descriptions of their performance. The present
dual-mode concept is vastly aided by today's electronics that can
be used to control initiation sites, making this shaped charge a
candidate for a single geometry, multi-mode warhead system. Such a
system now appears to have come into its own using precision
initiators and electronics that can control such initiators.
Further, modern day computational capability (FE analysis) can
provide design guidance on the involved complex jet formation
mechanics. For this purpose the ALEGRA code was used. The following
sections describe liner designs, initiation system, and warhead
function related to producing either tubular or constituted
jets.
CHARGE DESIGN
[0004] FIG. 1. Schematic of the Annular Shaped Charge design
depicting liner shape, position, and taper, along with explosive
charge and initiator system.
[0005] FIG. 2. ALEGRA calculations at various stages of initiation,
detonation, liner collapse, and jet formation: a) upper--tubular
jet design and b) lower--constituted jet design.
[0006] FIG. 3. Proposed Dual-mode warhead device that includes
multiple initiators (A & B) for varying the initiation radius
of the device.
LINER CONFIGURATION/INITIATION SCHEME
[0007] The present approach uses liner geometry of annular form
wherein the cross section of the liner has hemispherical, or
semicircular shape, although other shapes are possible. The
configuration is shown in FIG. 1. Here, the liner shape may be
described as a hemi-toroidal shell with the central axis of its
explosive charge aligned with the axis of the toroid. At least two
variations are possible; one with a uniform liner thickness (lower
dotted lines) and another that had a tapered liner (shown in upper
half). For the liner having uniform thickness, parameter A=0.
[0008] The charge consisted of high explosives (HE) such as 75/25
OCTOL. Typical length-to-diameter (L/D) ratio is 1/2, although
other ratios are possible. As such, the configuration represents a
compact design. The liner thickness could be composed of various
metals consistent with shaped charges to include copper, tantalum,
aluminum, iron, or molybdenum, for example. Starting liner
thickness could be from 2 to 4 percent of the charge diameter,
although other thicknesses could be used as well, based on previous
experience (Grace et al.) The computational physics code, ALEGRA,
was used to demonstrate function of this device in both modes as
shown in FIG. 2.
[0009] The initiator consisted of a relatively "thick" PETN based
explosive sheet disk (Primasheet), which was centered by a machined
polyethylene part that also centered the AR211 detonator on a PBX
booster pellet. Upon detonator activation, a circular detonation
wave will proceed outward radially until it interacts with and
initiates the OCTOL of the risers. The inner body of explosives is
protected from initiation by a polyethylene wave shaper (WS). The
risers start the detonation process in the OCTOL, which is
propagated into the main body of explosives. The initiation system
generates a "ring" detonation wave front, having annular shape. The
effective radius of initiation, I.sub.0, is defined at the center
of the riser.
[0010] A hemispherical cross section was chosen for the annular
liner of the hemispherical shape since this shape is more robust
with respect to off-axis initiation. When the wave is tilted,
initially the wave front "sees" symmetry of the spherical liner and
hence, a quality jet can be formed. The initiation scheme to
produce a tubular jet is designed so that the ensuing detonation
front will have annular symmetry (ring) so as to strike the liner
simultaneously about the pole region. However, the initiation
radius was adjusted somewhat to produce a jet having tubular shaped
walls that travel parallel to the charge axis without convergence
or divergence.
[0011] A constituted jet is produced when the charge is initiated
at a radius much greater than the pole radius. In this case, the
jet formed is directed both forward and inward in the form of a
flowing converging cone of jet material. When such converging jet
strikes the axis, it creates a newly formed or constituted on-axis
jet in solid form.
[0012] Computational Details
[0013] The ALEGRA 2-D Shock Wave Physics code [5] was exercised to
calculate jet formation. The modeling has axial symmetry, on a mesh
that extends 0.4 m in the axial direction and 0.15 m in the radial
direction. The mesh elements are 0.5 mm by 0.5 mm squares in a fine
mesh region that starts at the base of the main charge and extends
forward, and from the axis to a radius of 60 mm; beyond the fine
mesh region, the elements increase in size linearly to 2 mm as they
reach the edge of the mesh. Jet formation takes place in the fine
mesh region--the course mesh exists only to accommodate expansion
of explosive gasses.
[0014] The ALEGRA library HVRB model was used for OCTOL, while the
detonator and Primasheet material were taken from the ALEGRA
library JWL model "C-4". The wave shaper and other plastic parts
use the ALEGRA library sesame EOS for polyethylene with the Johnson
Cook elastic plastic model for Lexan. The copper liner uses the
ALEGRA library sesame EOS for copper with the Zerilli-Armstrong
elastic-plastic model. All void space around the test object is
filled with the ALEGRA sesame model for dry air.
[0015] FIG. 1 defines parameters explored with the following
physical dimensions of the charge/liner/initiator assembly, i.e.,
1) tapered vs. uniform wall liners, and 2) initiation radius. All
charges had D=101.6 mm and L=50.8 mm, outer liner radius R=19.6 mm,
liner pole radius was P=25.4 mm, B=50.8 mm, and C=6.35 mm.
[0016] FIG. 2 shows the annular lined charge using ALEGRA along
with a typical calculation of tubular and constituted jet formation
based on a single liner configuration but with two different
initiation radii, I.sub.0.
DISCUSSION AND SUMMARY
[0017] This application deals with a dual-mode warhead as a wall
breach device cutting large holes in targets (tubular jets) or as a
solid on-axis jetting device (constituted jet) for deep penetration
similar to conventional shaped charges. We propose that an overhead
attack or wall breach warhead could be designed having the annular
lined charge geometry investigated herein. A possible warhead
configuration is shown in FIG. 3, where two separate initiators are
included. Using present-day advanced electronics, the initiation
(detonator A or B) can be selected by the gunner before weapon
firing or conditionally "in flight" as target information is
acquired. The charge could possibly fit to a tandem device, where
if the target were concrete or brick, a large hole would be desired
as a precursor for a follow-through munition, for example. In this
case, detonator A would be activated to generate a tubular jet. If
the target were to be a hardened or armored structure, where deep
penetration is required, then detonator B would be activated. Thus,
the warhead can function in two separate but distinct modes (dual
mode) on command and provide appropriate and desired effects on
target in either case. Even in a single mode of peripheral
initiation, the warhead can serve as a more effective
fly-over/shoot down or top attack device. The enhanced velocity of
the reconstituted jet compared to an EFP (5.3 km/s vs. 2.5 km/s),
can provide higher kinetic energy effects on target while avoiding
detrimental crossing velocity effects.
[0018] It is believed that for the first time, a first formed jet
is being used as a moving liner to form a second or reconstituted
new jet. Thus in that regard, the authors are patenting a totally
new jetting mechanism for shaped charges.
REFERENCES
[0019] 1. Glass, C. M., Kronman, S., and Golaski, S. K., "The
Cookie Cutter Warhead," US Army Ballistic Research Laboratory
Report No. 1455, October 1969. [0020] 2. Liedel, D. J., "A Design
of an Annular-Jet Charge for Explosive Cutting," Doctoral
Dissertation, Drexel University, Philadelphia, Pa., June 1978.
[0021] 3. Fong, R., L. Thompson, W. Ng, "Toriodal Warhead
Development," in Proceedings 25.sup.th Int. Symp. on Ballistics,
Beijing, China, 2005. [0022] 4. Grace, F. I., S. K. Golaski, B. R.
Scott, "The Nature of Jets from Hemispherical Lined Shaped
Charges," in Proceedings 8.sup.th Int. Symp. on Ballistics,
Orlando, Fla., October 1984. [0023] 5. Robinson, A. C., et al,
ALEGRA Users Manual, Sandia National Laboratory, SAND2014-1236,
2014.
* * * * *