U.S. patent application number 11/699743 was filed with the patent office on 2008-07-31 for pressure bulkhead made of composite material for an aircraft.
This patent application is currently assigned to AIRBUS ESPANA, S.L.. Invention is credited to Francisco Jose Cruz Dominguez, Agustin Garcia Laja.
Application Number | 20080179459 11/699743 |
Document ID | / |
Family ID | 39666851 |
Filed Date | 2008-07-31 |
United States Patent
Application |
20080179459 |
Kind Code |
A1 |
Garcia Laja; Agustin ; et
al. |
July 31, 2008 |
Pressure bulkhead made of composite material for an aircraft
Abstract
The present invention relates to a curved rear pressure bulkhead
(1) made of a composite material, comprising three layers: an outer
layer (2) and an inner layer (3) symmetrical with one another,
which are made of a fiber laminate, and the intermediate layer or
core (4) made of a lightweight material. With such a sandwich-type
shape, the resulting bulkhead (1) is able to withstand the bending
loads coming from the strain and pressurization of the fuselage
without having to increase its stiffness by means of using some
type of stiffener. The bulkhead (1) comprises a ring (6) that is
attached to the ends of the sandwich shape. This ring (6) is split
into several parts (8) to facilitate the assembly of the bulkhead
(1) made of composite material to the fuselage skin (5).
Inventors: |
Garcia Laja; Agustin;
(Madrid, ES) ; Cruz Dominguez; Francisco Jose;
(Madrid, ES) |
Correspondence
Address: |
LADAS & PARRY LLP
26 WEST 61ST STREET
NEW YORK
NY
10023
US
|
Assignee: |
AIRBUS ESPANA, S.L.
|
Family ID: |
39666851 |
Appl. No.: |
11/699743 |
Filed: |
January 30, 2007 |
Current U.S.
Class: |
244/119 ;
29/458 |
Current CPC
Class: |
Y10T 156/1043 20150115;
B64C 1/10 20130101; Y10T 29/49885 20150115 |
Class at
Publication: |
244/119 ;
29/458 |
International
Class: |
B64C 1/10 20060101
B64C001/10; B23P 25/00 20060101 B23P025/00 |
Claims
1. A rear pressure bulkhead (1) for aircraft fuselage made of a
composite material, characterized in that it comprises three
layers: an outer layer (2) formed by a fiber laminate, an inner
layer (3) formed by a fiber laminate and an intermediate layer or
core (4) made of a lightweight material, the laminates of the outer
layer (2) and inner layer (3) being symmetrical with one
another.
2. A rear pressure bulkhead (1) for aircraft fuselage made of a
composite material according to claim 1, characterized in that its
end (9) is formed by a fiber laminate.
3. A rear pressure bulkhead (1) for aircraft fuselage made of a
composite material according to claims 1, characterized in that it
comprises a ring (6) divided into pieces (8) to which the ends (9)
of the bulkhead (1) are fixed so as to attach the bulkhead (1) to
the aircraft fuselage.
4. A rear pressure bulkhead (1) for aircraft fuselage made of a
composite material according to claim 1, characterized in that the
core (4) is foam.
5. A rear pressure bulkhead (1) for aircraft fuselage made of a
composite material according to claim 1, characterized in that the
core (4) is honeycomb-like.
6. A rear pressure bulkhead (1) for aircraft fuselage made of a
composite material according to claim 1, characterized in that the
composite material is CFRP.
7. A rear pressure bulkhead (1) for aircraft fuselage made of a
composite material according to claim 1, characterized in that
there is an adhesive layer between the outer layer (2) and the core
(4) and between the inner layer (3) and the core (4).
8. A manufacturing process for manufacturing a rear pressure
bulkhead (1) made of composite material according to claim 1,
characterized in that it comprises the following steps: a) curing
the layer of the core 4 with a planar plate shape b) heat machining
and forming the layer of the core 4 so that it acquires its final
shape; c) stabilizing the layer of the core 4 so that its shape is
not modified during the final curing of the bulkhead 1; d)
laminating the outer and inner laminates 2, 3 of the bulkhead 1
with a fiber placement machine or manually on a male jig on both
sides of the layer of the core 4; e) curing the assembly of the
laminates 2, 3 and the core 4 in an autoclave.
Description
OBJECT OF THE INVENTION
[0001] The present invention relates to a rear pressure bulkhead
for an aircraft made of composite material as well as to the
manufacturing process thereof.
BACKGROUND OF THE INVENTION
[0002] The pressure bulkhead for an aircraft is the structural
component that supports the pressure of the fuselage of the
aircraft at its ends. The strain that the fuselage of the aircraft
is subjected to, particularly when the fuselage is depressurized,
in this case adding the negative pressure of the fuselage with the
strain due, for example, to the loads from the vertical stabilizer,
are transmitted to the rear pressure bulkhead, making it bend and
buck and even collapse if it is not stiff enough. In addition, it
is necessary, mainly where modern aircraft designs are concerned,
to manufacture pressure bulkheads minimizing their weight while
maintaining their stiffness at the same time.
[0003] Pressure bulkheads made of metal, particularly aluminum, are
known in the art, although these designs require metal stiffeners
to make the bulkhead stiff enough to support the fuselage
strains.
[0004] In addition, pressure bulkheads made of a composite
material, mainly CFRP (Carbon Fiber Reinforced with Plastic) are
known which also require stiffeners made of CFRP to support the
strain coming from the fuselage.
[0005] Document U.S. Pat. No. 5,062,589 describes a pressure
bulkhead for an aircraft made of a composite material and locally
stiffened in its high loaded areas by means of introducing foam,
thus increasing the thickness of the bulkhead in these areas.
However, it is necessary to manufacture this bulkhead in several
sections so that it can be correctly assembled on the skin of the
aircraft fuselage.
[0006] The object of this invention is a pressure bulkhead for an
aircraft made of a composite material that solves the drawbacks of
the prior art.
SUMMARY OF THE INVENTION
[0007] This invention proposes a curved rear pressure bulkhead
comprising three layers: the outer and inner layers, symmetrical in
relation to one another, are formed by a fiber laminate, the
intermediate layer or core being formed by a lightweight material.
With such a sandwich-type shape, the resulting bulkhead is able to
withstand the bending loads coming from the strain and
pressurization of the fuselage without having to increase its
stiffness by means of using any kind of stiffener.
[0008] The bulkhead made of the composite material according to
this invention is furthermore made in a single piece without the
need to be split into sections facilitating the assembly on the
aircraft fuselage skin, therefore a great weight reduction is
achieved by means of eliminating any type of joint while at the
same time the assembly process is clearly simplified by reducing
the assembly time due to the greater integration of the assembly
process. The bulkhead of the invention comprises a ring that is
attached to the ends of the sandwich part. this ring is split into
several pieces so that it makes easier the assembly of the bulkhead
made of composite material on the fuselage skin.
[0009] The invention also relates to the manufacturing process for
manufacturing a pressure bulkhead made of a composite material,
comprising the steps of: [0010] a) forming and curing the core
layer of the bulkhead; [0011] b) laminating on a male jig the
preimpregnated layers for the outer and inner faces of the bulkhead
on both sides of the core layer, already cured and machined. [0012]
c) curing the whole part: the outer and inner faces and the
core.
[0013] Other features and advantages of the present invention will
be understood from the following detailed description of the
illustrative embodiments of its object in relation to the attached
figures.
DESCRIPTION OF THE FIGURES
[0014] FIG. 1 shows a schematic view of the-position of the rear
pressure bulkhead in a typical pressurized aircraft.
[0015] FIG. 2 shows a schematic view of the conventional stiffened
rear pressure bulkhead of a pressurized aircraft.
[0016] FIG. 3 shows a schematic sectional view of the pressure
bulkhead made of a composite material according to the present
invention.
[0017] FIG. 4 shows a detail of the ring for attaching the bulkhead
made of composite material according to the invention to the
aircraft fuselage skin.
[0018] FIG. 5 shows a sectional view of the detail of the ring for
attaching the bulkhead made of composite material according to the
invention to the aircraft fuselage skin.
[0019] FIG. 6 shows a detail of the ring for attaching the bulkhead
made of composite material according to the invention.
DETAILED DESCRIPTION OF THE INVENTION
[0020] The present invention proposes a curved rear pressure
bulkhead 1 made of composite material, preferably in CFRP, made
from carbon fibers and epoxy resin. The main advantage of CFRP is
its strength/weight ratio as it is a material used to manufacture
very lightweight and strong structures that are easy to optimize in
relation to those made of isotropic materials. These advantages are
essential for the design of pressure bulkheads for aircrafts.
[0021] The pressure bulkhead according to the invention is made in
a single piece in a 360.degree. spherical cap shape as can be seen
in FIG. 3 and is made of two fiber laminates, an outer laminate 2
and an inner laminate 3, and a core 4 that is introduced in
between. The laminates 2, 3 are made of pre-impregnated fiber plies
that are positioned manually or by means of a fiber placement
machine. The laminates 2 and 3 arranged on both sides of the core 4
are symmetrical in relation to one another, and it is not necessary
for each laminate 2, 3 to be individually symmetrical. There can
also be an adhesive layer between the laminates 2 and 3 and the
core 4 which is necessary for preventing the laminates 2, 3 from
debonding from the core 4 due to a wrinkle that may appear in the
laminates 2, 3 as an effect of compression loads on the mentioned
laminates 2, 3.
[0022] The main advantage of a bulkhead 1 made of composite
material according to the invention with a sandwich-type shape
compared to any conventional monolithic bulkhead 10, as shown in
FIG. 2, is that the bulkhead 1 of the invention withstands the
bending load alone without the need to be stiffened with any type
of stiffener 12, as in the case of the conventional bulkhead 10.
This makes the pressure bulkhead 1 work more efficiently against
loads coming from the strain of the fuselage while at the same time
entails a weight reduction in comparison with the designs of
current stiffened bulkheads 10. In addition, a pressure bulkhead 1
according to the invention absorbs the membrane loads coming from
the pressurization of the fuselage in the same way as any
conventional monolithic bulkhead 10.
[0023] The core 4 comprised between the two laminates 2, 3 is made
of a lightweight material which can be formed or machined and
which, according to a first preferred embodiment of the invention,
is a foam. This foam minimizes typical water intake problems in
sandwich-type composite structures while at the same time it is an
optimal solution in terms of weight and easy machining.
[0024] According to another preferred embodiment of the invention,
the core 4 comprised between the laminates 2 and 3 is made of a
honeycomb-type structure that can be made of paper, metal or any
other material, which structure allows exponentially increasing the
stiffness of the pressure bulkhead 1 without affecting the weight
of the bulkhead 1 and is lighter than the foam core 4.
[0025] The radius of the pressure bulkhead 1 will be a trade-off
between the minimum weight of the bulkhead 1 and the maximum space
for systems and accessibility inside the aircraft.
[0026] The pressure bulkhead 1 made of composite material is
manufactured in a single piece, without the need to be split into
sections 11 like a conventional bulkhead 10. To allow the assembly
of the bulkhead 1 to the aircraft fuselage skin 5, the bulkhead 1
also comprises a ring 6 made by means of resin transfer molding, or
RTM, or it is made of titanium, divided into several pieces 8 to
make easier the attachment of the bulkhead 1 to the fuselage skin
5. As can be seen in FIGS. 4 and 5, the ends of the pressure
bulkhead 1 are composed of only one fiber laminate 9, so that these
ends 9 are attached to the ring 6 by means of rivets 7, attaching
at the same time sections 8 of the ring 6 to the aircraft fuselage
skin 5 by means of the corresponding rivets 17.
[0027] The present invention also proposes in a second aspect a
manufacturing process for manufacturing a pressure bulkhead 1 made
of composite material comprising two inner and outer laminates 2
and 3, respectively, and a core 4 made of a lightweight material,
comprising the following steps: [0028] a) curing the layer of the
core 4 with flat plate shape [0029] b) machining and hot-forming
the layer of the core 4 so that it takes on its final shape; [0030]
c) stabilizing the layer of the core 4 so that its shape is not
modified during the final curing process of the bulkhead 1; [0031]
d) laminating the outer and inner laminates 2, 3 of the bulkhead 1
with a fiber placement machine or manually on a male jig on both
sides of the layer of the core 4; [0032] e) curing the joint of the
laminates 2, 3 and the core 4 in an autoclave.
[0033] Any modifications comprised within the scope defined by the
following claims can be introduced in the preferred embodiments
just described.
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