Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
CA 02370777 2002-02-08
COLLAPSIBLE CELLULAR STRUCTURE
BACKGROUND OF THE INVENTION
(i) Field of the Invention
The present invention relates to a collapsible cellular or honeycomb structure
and, more particularly, relates to novel cellular or honeycomb structures of
metallic
knitted or woven mesh capable of being crushed.
(ii) Description of the Related Art
Cellular structures made from thin sheet metal or metal foil are known for use
in space and aerospace applications, in particular in jet engines, because
they provide
a high stiffness to weight ratio and high mechanical energy absorption
capabilities and
acoustic damping while being light in weight.
U.S. Patent No. 3,867,061 issued February 18, 1975 typifies a conventional
prior art honeycomb shroud for rotor blades for turbines in which the
honeycomb cell
walls are made from nickel-base heat-resistant alloys and the honeycomb strips
are
brazed or resistance welded to a back-up ring.
U:S. Patent No. 4063,742 issued December 20, 1977 discloses another
embodiment of prior art abradable fluid seal for use in gas turbines
consisting of a
conventional honeycomb made by conventional honeycomb equipment in which
abutting three-sided semi-hexagonal strips each having a pair of flat slanted
sides and
a flat crest of equal length standing on edge are resistance welded together
at the
crests.
Honeycomb structures typically are fabricated by building up the structure
layer by layer to result in a three dimensional body having a height
determined by the
width to which the ribbon had been slit prior to corrugation. The length of
the
structure is parallel to the plane of the double walls or nodes and the width
is
CA 02370777 2002-02-08
-2-
represented by the direction of layer build up. Such a cellular body is brazed
to face
sheets to form a sandwich skin or brazed to backplates of a ring or ring
segments to
form a seal. Such brazing does not only join the cellular structure body to
the face
sheet or backplate but also contributes significantly to the stiffness of the
cellular
structure itself. This is due to the fact that the brazing alloy, in a liquid
state and due
to capillary action, rises up the gap formed by the two neighbouring walls of
the node,
thereby wetting the abutting surfaces of said node walls and, after
resolidification of
the braze filler metal, forms a stiffened cellular structure. The braze flow
up the nodal
walls is referred to as "wicking". Such wicking is essential to provide a
brazed
cellular structure with good mechanical behaviour at high temperatures to
resist
combined thermal and mechanical loads.
It is an object of the present invention, on the other hand, to provide a
light-
weight, collapsible, metallic cellular structure which can be subsequently re-
opened
and dismantled.
It is another object of the present invention to provide a light-weight,
collapsible, cellular structure such as a honeycomb structure capable of
receiving and
housing electrical wires and cables for providing effective shielding and
grounding of
the wires and cables.
Summary of the Invention
In accordance with the present invention there are provided novel cellular
structures made from knitted or woven metal wire mesh having weak structural
strength and poor stiffness to permit facile crushing and collapse while
allowing the
structures to be easily re-opened and dismantled.
In its broadest form this is achieved through a cellular honeycomb structure
which comprises a plurality of abutting semi-hexagonal strips or sheets of
knitted or
woven metal mesh, each having alternating flat slanted sides interconnected by
a flat
crest, the abutting strips joined together at the adjacent flat crests by
resistance or
CA 02370777 2002-02-08
-3-
laser welds to form generally hexagonal cells having double wall crests or
nodes, the
slanted sides and crests preferably having an equal length.
Preferably the strips or sheets are knitted or woven thin wires of phosphor
bronze, nickel-based alloys, stainless steels, or nickel and copper alloys. A
pair of
abutting generally semi-hexagonal corrugated metal strips or sheets of knitted
or
woven metal mesh can be joined together at adjacent flat crests by resistance
or laser
spot welds to define a row of equispaced cells for receiving wires therein.
More than
two abutting generally semi-hexagonal corrugated metal strips or sheets of
knitted or
woven mesh can be joined together at adjacent flat crests by resistance or
laser spot
welds to define adjacent rows of cells for receiving a bundle of wires
therein.
The novel crushable honeycomb structure of the invention can be used for
shielding and grounding electrical wires and cables such as through bulkheads
in
aircraft and boats.
Brief Description of the Drawings
The crushable honeycomb structure of the invention will now be described
with reference to the accompanying drawing, in which:
Figure 1 is a plan view of the honeycomb cellular structure of the invention.
Description of the Preferred Embodiments
Referring to the drawing, Figure 1 illustrates a honeycomb cellular structure
10 fabricated from a plurality of metal strips or sheets 12 of corrugated
knitted or
woven metal mesh having a three-sided, semi-hexagon shape consisting of a pair
of
flat slanted sides 14, 16 interconnected by adjacent intermediary flat crests
18, 19.
Sides 14, 16 and crests 18, 19 preferably are of equal length. The adjacent
strips 12,
12a, 12b, 12c are joined together at their abutting crests 18, 19 such as by
resistance
welds or by laser spot welds 21 to form the three-dimensional body 10. The
joining
of more than two adjacent strips or sheets together, such as strips or sheets
12a, 12b
CA 02370777 2002-02-08
-4-
and 12c , as typified in Figure l, provides a plurality of adjacent cells
depicted by
numerals 20a, 20b, 20c and 20d for receiving a bundle or bundles of wires or
cables
therein, not shown. The joining of a pair of adjacent strips or sheets
together, such as
strips or sheets 12a and 12b, provides a row of equispaced cells such as cells
20a and
20b for receiving a row of equispaced wires therein.
The strips or sheets of knitted or woven mesh preferably are produced from
thin wires of phosphor bronze, nickel and copper alloys such as MONEL TM,
nickel-
base alloys or stainless steels. The resulting honeycomb mesh can receive
electrical
wires or cables through the cells, such as in aircraft bulkhead installations,
and the
honeycomb structure crushed to effectively shield and electrically ground the
wires
and cables therein. The crushed honeycomb structure can be easily re-opened to
allow dismantling of the installations for re-use.
It will be understood, of course, that modifications can be made in the
embodiments of the invention illustrated and described herein without
departing from
the scope and purview of the invention as defined by the appended claims.
