BLAST PANEL ASSEMBLY

ASSEMBLAGE DE PANNEAUX D'EXPLOSION

English Abstract

A blast panel assembly includes a laminate formed of a plurality of glued together sheets of plywood mounted in a metal frame.

French Abstract

Un assemblage de panneau à lépreuve des explosions comprend un stratifié formé dun ensemble de panneaux de contreplaqué collés ensemble et montés dans un cadre en métal.

Claims

What is claimed is:
1. A blast panel assembly comprising:
a plurality of sheets of plywood glued together to form a laminate;
a metal frame surrounding the laminate,
wherein the metal frame includes:
a metal outer frame comprising permanently connected frame members,
and
metal brackets permanently attached to the metal outer frame;
a plurality of spaced apart bolts extending completely through the metal
brackets and the laminate; and
nuts on said bolts securing the laminate to the metal frame.
2. A blast panel assembly comprising:
a plurality of sheets of plywood glued together to form a laminate;
a metal frame surrounding the laminate,
wherein the metal frame includes:
a metal outer frame comprising permanently connected frame members;
a plurality of spaced apart bolts extending completely through the metal
outer frame and the laminate; and
nuts on said bolts securing the laminate to the metal frame.
3. The blast panel assembly of claim 1 or 2, wherein each layer of the
laminate is formed
by a plurality of sheets of plywood with abutting edges.
4. The blast panel assembly of claim 3, wherein the abutting edges of the
sheets of
plywood in one layer are out of alignment with the abutting edges of the
sheets of plywood in
any adjacent layer of the laminate.
5. The blast panel assembly of claim 1, wherein said outer frame includes
square cross
section metal tubing surrounding said sheets of plywood; and said brackets
include angle iron
strips on an inner side of the tubing, said bolts extending through said
strips and said plywood
sheets for connecting the sheets to the angle iron strips.
Date Recue/Date Received 2023-05-16

6. The blast panel assembly of claim 2, wherein said outer frame includes
metal channel
members of U-shaped cross section for receiving said sheets of plywood, said
bolts and nuts
connecting said sheets of plywood to said metal channel members.
7. The blast panel assembly of claim 4, wherein the laminate includes nine
layers of three-
quarter inch select grade plywood, whereby the assembly is capable of
withstanding blast loads
of 25-35 psi and impulses of 90-123 psi-ms.
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Date Recue/Date Received 2023-05-16

Description

CA 02950477 2016-12-02
BLAST PANEL ASSEMBLY
This invention relates to a blast resistant panel assembly.
Blast resistant panels are by no means new. One form of blast panel consists
of
heavy steel or iron panels. Other impact resistant panels are described in US
Patents
Nos. 4,242,406, issued to El Bouhnini et al on December 30, 1980, 6,699,575,
issued
to Habil J. Dagher et al on March 2, 2004, 7,406,806, issued to Gerald
Hallissy et al on
August 5, 2008 and 8,596,018, issued to Habib J. Dagher et al on December 3,
2013.
The panel described in the Bouhnini et al US Patent No. 6,119,422 includes
layers of gypsum board bonded together with an adhesive mesh.
The Dagher et al US Patent No. 6,699,574 discloses a wood sheathing panel
incorporating strips of fiber reinforced polymer in the perimeter or corners
of the panel.
The strips cover an area of 5-50 percent of surface area of the panel.
The Dagher et al US Patent No. 8,596,018 discloses a blast panel comprising a
wood member having a compression side and a tension side. The tension side of
the
wood number is coated with a layer of fiber reinforced polymer.
The blast panels described in the above-listed patents would be expensive to
manufacture, because they incorporate at least two materials, one of which is
a
polymer or plastic.
An object of the present invention is to provide a relatively simple blast
panel,
which is inexpensive and easy to produce.
In its simplest form, the invention relates to a blast panel comprising a
plurality of
sheets of plywood, which are laminated by gluing the sheets together.
Preferably, the
laminated sheets are mounted in a metal frame.
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BRIEF DESCRIPTION OF THE DRAWINGS
The invention is described below with reference to the accompanying drawings,
which illustrate a preferred embodiment of the invention, and wherein:
Figure 1 is a schematic isometric view of the blast panel assembly as viewed
from the rear and above;
Figure 2 is a schematic, cross-sectional view of a bottom portion of the blast
panel of Fig. 1; and
Figure 3 is an exploded, isometric view of a plywood panel laminate used in
the
blast panel assembly of Figs. 1 and 2.
With reference to Figs. 1 and 2, the basic elements of the blast panel
assembly
include a hollow rectangular frame indicated generally at 1, strips 2 of angle
iron and a
plurality of laminated sheets 3 of plywood.
The frame 1 is defined by four square cross section steel tubes 4 which are
welded together to form a rectangle. The frame 1 need not be rectangular, it
could be
circular, triangular or any other shape. The strips 2 of angle iron are welded
to the inner
sides of the frame 1 and to each other, forming a rectangular bracket inside
of the
frame 1. The plywood sheets 3 are connected to the angle iron strips 2 by
carriage
bolts 5 extending through the angle iron strips 2 and the laminated plywood
sheets 3,
and nuts 6. The frame 1 can also be formed by U-shaped channel members (not
shown).
As best shown in Fig. 2, the plywood sheets 3 are laminated by gluing them
together with a continuous layer 8 of multi-purpose glue. A suitable glue is
Lapage
multi-purpose glue. The sheets 3 are preferably three-quarter inch select
grade
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CA 02950477 2016-12-02
plywood. The sheets 3 are laminated so that the joints 10 between the stacked
sheets
of one layer 7 are not aligned with the joints 10 between the next layer 7. As
will be
appreciated by a person skilled in the art to which the present invention
relates, the
sheets 3 can be stacked so that their long edges are horizontal, or the sheets
can be
arranged side by side with their long edges vertical so long as the abutting
edges of the
sheets forming one layer 7 are out of alignment with the abutting edges of the
sheets in
any adjacent layer 7. When using standard 4' x 8' sheets of plywood, one of
the sheets
(in this case the top or bottom sheet) is cut in half lengthwise before
laminated the
sheets, and the arrangement of the sheets in the next layer 7 is reversed from
top to
bottom. Thus, alignment of the joints 10 between sheets 3 in adjacent layers 7
is
avoided. With the arrangement of sheets 3 shown in Fig. 3, if one sheet of
plywood is
cut lengthwise in the middle, the result is two 2' x 8' sheets which are used
to form the
top end of one layer 7 and the bottom end of an adjacent layer 7. The
resulting
laminate of sheets will have dimensions of approximately 10' in height and 8'
in width.
Tests were conducted on a panel assembly in accordance with the invention
including a laminate of nine layers of three-quarter inch plywood sheets. The
laminated
plywood sheets 3 had three-quarter inch bolt holes drilled at six inches apart
along the
vertical edges of the nine sheet 8' x 8' laminate for mounting in steel
framing elements.
Test loads were developed by detonating two batches of ammonium nitrate/fuel
oil
using bulk industrial explosive mixture. Each shot used a different explosive
weight and
standoff from the test specimen. Five pressure gauges were mounted on the
steel
plates on the front of the reaction structure surrounding the specimen. Two
laser-based
displacement readers were positioned along the vertical center line of the
panel for
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each test. The ranges of gauge readings recorded for positive phase pressure
and
impulse are presented in Table 1.
Table 1
Test Number Pressure in psi Impulse in psi-ms
(kPa) (kPa-ms)
1 33-35 (230-240)
90-103 (620-710)
2 25-28 (170-190)
96-123 (660-850)
The maximum displacement of the panel did not exceed 0.4 inch (10 mm) for
either test within the first 150 ms of recorded responses. No permanent panel
deformation was observed in either case during post-test inspection, i.e., the
panel
returned to its original pre-test position as a result of an elastic response.
Accordingly,
it is reasonable to expect that assemblies with a similar laminate thickness
and span
can likely sustain significantly higher blast loads than those tested without
permanent
deformation. The panels can potentially take even higher loads where permanent
panel deformation is acceptable, e.g., where panels are to be subjected to a
one-time
blast event and only need to sustain capacity to allow for personnel egress.
4

Representative Drawing