U.S. patent application number 16/748910 was filed with the patent office on 2020-09-10 for panel and method of forming a three-sheet panel.
This patent application is currently assigned to The Boeing Company. The applicant listed for this patent is The Boeing Company. Invention is credited to Lee C. Firth, Gregory A. Foltz, Marc R. Matsen, David S. Nansen, Carey E. Wilkinson, Michael R. Zolnowski.
Application Number | 20200282698 16/748910 |
Document ID | / |
Family ID | 1000004856384 |
Filed Date | 2020-09-10 |
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United States Patent
Application |
20200282698 |
Kind Code |
A1 |
Matsen; Marc R. ; et
al. |
September 10, 2020 |
PANEL AND METHOD OF FORMING A THREE-SHEET PANEL
Abstract
A panel comprises a first face sheet and a second face sheet
spaced apart from the first face sheet. The panel further comprises
a core sheet intercoupled between the first face sheet and the
second face sheet. Each of the first and second face sheets is made
of a material having a thermal expansion that is different from the
thermal expansion of the other face sheet.
Inventors: |
Matsen; Marc R.; (Seattle,
WA) ; Firth; Lee C.; (Renton, WA) ; Nansen;
David S.; (Lopez Island, WA) ; Zolnowski; Michael
R.; (Saint Charles, MO) ; Wilkinson; Carey E.;
(Summerville, SC) ; Foltz; Gregory A.; (San Diego,
CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
The Boeing Company |
Chicago |
IL |
US |
|
|
Assignee: |
The Boeing Company
Chicago
IL
|
Family ID: |
1000004856384 |
Appl. No.: |
16/748910 |
Filed: |
January 22, 2020 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
15443235 |
Feb 27, 2017 |
10569504 |
|
|
16748910 |
|
|
|
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C22C 30/00 20130101;
B32B 2262/101 20130101; B32B 15/015 20130101; B32B 2307/30
20130101; B32B 7/02 20130101; C22C 19/05 20130101; B32B 3/28
20130101; B32B 2605/18 20130101; B32B 18/00 20130101; B32B 2250/03
20130101; B32B 2307/732 20130101; B32B 2262/106 20130101; B32B
9/005 20130101; B32B 7/027 20190101; B32B 3/12 20130101; B32B 1/00
20130101; C22C 19/055 20130101; B32B 2250/40 20130101 |
International
Class: |
B32B 7/02 20060101
B32B007/02; B32B 15/01 20060101 B32B015/01; C22C 19/05 20060101
C22C019/05; B32B 7/027 20060101 B32B007/027; B32B 18/00 20060101
B32B018/00; B32B 3/12 20060101 B32B003/12; B32B 9/00 20060101
B32B009/00; B32B 3/28 20060101 B32B003/28; B32B 1/00 20060101
B32B001/00 |
Claims
1. A panel comprising: a first face sheet; a second face sheet
spaced apart from the first face sheet; and a core sheet
intercoupled between the first face sheet and the second face
sheet, wherein each of the first and second face sheets is made of
a material having a thermal expansion that is different from the
thermal expansion of the other face sheet.
2. The panel of claim 1 wherein the material of the first face
sheet comprises a low thermal expansion material, and the material
of the second face sheet comprises a high thermal expansion
material.
3. The panel of claim 2 wherein the material of the first face
sheet comprises INCOLOY Alloy 909, and the material of the second
face sheet comprises INCONEL Alloy 625.
4. The panel according to claim 1 wherein the first face sheet has
a coefficient of thermal expansion between about 4.0 ppm/.degree.
F. and about 5.5 ppm/.degree. F.
5. The panel according to claim 4 wherein the second face sheet has
a coefficient of thermal expansion between about 7 ppm/.degree. F.
and about 10 ppm/.degree. F.
6. The panel according to claim 5 wherein the core sheet has a
coefficient of thermal expansion between about 7 ppm/.degree. F.
and about 10 ppm/.degree. F.
7. The panel according to claim 6 wherein the first face sheet can
withstand a temperature up to or above 1000.degree. F. higher than
the second face sheet without degradation of the panel when the
first face sheet is exposed to more heat than the second face
sheet.
8. The panel according to claim 1 wherein the first face sheet has
a thickness between about 0.10 inches (0.025 centimeters) and about
0.125 inches (0.318 centimeters) and the second face sheet has a
thickness between about 0.01 inches (0.025 centimeters) and about
0.125 inches (0.318 centimeters).
9. The panel according to claim 8 wherein the core sheet has a
thickness between about 0.01 inches (0.025 centimeters) and about
0.10 inches (0.254 centimeters).
10. The panel according to claim 1 wherein the first face sheet has
a density between about 0.25 lbs/in.sup.3 and about 0.40
lbs/in.sup.3 and the second face sheet has a density between about
0.25 lbs/in.sup.3 and about 0.40 lbs/in.sup.3.
11. The panel according to claim 10 wherein the core sheet has a
density between about 0.25 lbs/in.sup.3 and about 0.40
lbs/in.sup.3.
12. The panel according to claim 1 wherein the panel comprises a
superplastic panel.
13. The panel according to claim 1 wherein the panel is an expanded
panel.
14. The panel according to claim 1 wherein the first face sheet
comprises an iron alloy and the second face sheet comprises a
nickel alloy.
15. The panel according to claim 14 wherein the core sheet
comprises a nickel alloy.
16. The panel according to claim 1 wherein the first face sheet
comprises iron, nickel, cobalt, niobium and titanium, and wherein
the second face sheet comprises nickel, chromium, iron, molybdenum
and niobium.
17. The panel according to claim 16 wherein the core sheet
comprises nickel, chromium, iron, molybdenum and niobium.
18. The panel according to claim 1 wherein the first face sheet is
formed from an iron alloy comprising 35.0 wt % to 40.0 wt % nickel,
12.0 wt % to 16.0 wt % cobalt, 4.3 wt % to 5.2 wt % niobium, and
1.3 wt % to 1.8 wt % titanium.
19. The panel according to claim 1 wherein the second face sheet is
formed from a nickel alloy comprising at least 58.0 wt % nickel,
20.0 wt % to 23.0 wt % chromium, at most 5.0 wt % iron, 8.0 wt % to
10.0 wt % molybdenum, and 3.15 wt % to 4.15 wt % niobium.
20. The panel according to claim 1 wherein the core sheet is formed
from a nickel alloy comprising at least 58.0 wt % nickel, 20.0 wt %
to 23.0 wt % chromium, at most 5.0 wt % iron, 8.0 wt % to 10.0 wt %
molybdenum, and 3.15 wt % to 4.15 wt % niobium.
Description
PRIORITY
[0001] This application is a divisional of U.S. Ser. No. 15/443,235
filed on Feb. 27, 2017.
FIELD
[0002] The present application relates to multilayer structures,
and is particularly directed to a panel and a method of forming a
three-sheet panel.
BACKGROUND
[0003] Multilayer structures are typically formed from a core sheet
sandwiched between two face sheets. The core sheet of a multilayer
structure defines substantial void space and has an effective
cross-sectional thickness that is substantially greater than the
cross-sectional thicknesses of the adjacent face sheets. Therefore,
multilayer structures typically possess relatively high strength
and stiffness at relatively low weight. As such, multilayer
structures are used in various aerospace applications.
[0004] Superplastic forming is a known technique for manufacturing
multilayer structures, such as expanded two-sheet panels (no core
sheet) and expanded three-sheet panels (a core sheet positioned
between two face sheets), which may be used as alternatives to
traditional honeycomb multilayer structures. Superplastic forming
is a metal forming process that takes advantage of the
superplasticity of certain materials, such as titanium alloys,
aluminum alloys and nickel alloys, at elevated temperatures. When
such materials are heated to a superplastic state, they become
pliable and can be expanded (e.g., by gas pressure) against a mold
to achieve a desired shape. During expansion, the material can
experience elongation of several hundred percent.
[0005] While the void space in multilayer structures advantageously
reduces density (increases bulk), it presents a complication when a
multilayer structure is subjected to thermally induced stress due
to thermal gradients in the multilayer structure. For example, the
multilayer structure may comprise a three-sheet panel (i.e., a core
sheet positioned between two face sheets) that is used in a thrust
reverser of an aircraft engine. In this example implementation, one
face sheet (i.e., the inner sheet) faces toward the aircraft
engine, and the other face sheet (i.e., the outer sheet) on the
other side of the core sheet faces away from the aircraft engine.
Since the inner sheet is closer to the aircraft engine than the
outer sheet, the inner sheet is exposed to higher temperatures than
the outer sheet during operation of the aircraft engine. The
thermal gradient between the inner sheet and the outer sheet
results in thermally induced stress in the three-sheet panel.
[0006] Accordingly, those skilled in the art continue with research
and development efforts in the field of multilayer structures
including three-sheet panels.
SUMMARY
[0007] In one aspect, a panel comprises a first face sheet and a
second face sheet spaced apart from the first face sheet. The panel
further comprises a core sheet intercoupled between the first face
sheet and the second face sheet. Each of the first and second face
sheets is made of a material having a thermal expansion that is
different from the thermal expansion of the other face sheet.
[0008] In another aspect, a method is provided of forming a
three-sheet panel. The method comprises selecting a first face
sheet made of a first thermal expansion material, and selecting a
second face sheet made of a second thermal expansion material that
is different from the first thermal expansion material. The method
also comprises attaching each of the selected first and second face
sheets to a core sheet to sandwich the core sheet between the first
and second face sheets to provide a precursor panel. The method
further comprises processing the precursor panel to form the
three-sheet panel.
[0009] In yet another aspect, a method is provided of forming a
three-sheet panel. The method comprises selecting a first face
sheet made of INCOLOY Alloy 909, and selecting a second face sheet
made of INCONEL Alloy 625. The method also comprises selecting a
core sheet made of INCONEL Alloy 625, and attaching each of the
selected first and second face sheets to the core sheet to sandwich
the core sheet between the first and second face sheets to provide
a precursor panel. The method further comprises processing the
precursor panel to form the three-sheet panel.
[0010] In still another aspect, a method is provided of forming a
three-sheet panel. The method comprises attaching a first face
sheet and a second face sheet to a core sheet to sandwich the core
sheet between the first and second face sheets. The method also
comprises superplastic forming the first face sheet at a different
rate of expansion than the second face sheet to form the
three-sheet panel.
[0011] Other aspects will become apparent from the following
detailed description, the accompanying drawings and the appended
claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] FIG. 1 is cross-sectional view of a superplastic three-sheet
panel constructed in accordance with an example embodiment.
[0013] FIG. 2 is a thermal expansion profile of example suitable
materials that can be used to make the superplastic panel of FIG.
1.
[0014] FIG. 3 is cross-sectional view of a superplastic three-sheet
panel constructed in accordance with another example
embodiment.
[0015] FIG. 4 is a flow diagram illustrating an example method of
superplastic forming a three-sheet panel in accordance with an
example embodiment.
[0016] FIG. 5 is a flow diagram illustrating another example method
of superplastic forming a three-sheet panel in accordance with
another example embodiment.
[0017] FIG. 6 is a flow diagram illustrating another example method
of superplastic forming a three-sheet panel in accordance with
another example embodiment.
[0018] FIG. 7 is a flow diagram of an aircraft manufacturing and
service methodology.
[0019] FIG. 8 is a block diagram of an aircraft.
DETAILED DESCRIPTION
[0020] The present application is directed to panels and methods of
forming three-sheet panels. The specific panel, forming method, and
the industry in which the panel and forming method are implemented
may vary. It is to be understood that the disclosure below provides
a number of embodiments or examples for implementing different
features of various embodiments. Specific examples of components
and arrangements are described to simplify the present disclosure.
These are merely examples and are not intended to be limiting.
[0021] By way of example, the disclosure below describes
superplastic panels and methods of superplastic forming three-sheet
panels for aircraft. More specifically, the disclosure below
describes a superplastic formed three-sheet panel for use in a
thrust reverser of an aircraft engine. The three-sheet panel and
method of superplastic forming the three-sheet panel may be
implemented by an original equipment manufacturer (OEM) for
manufacturing superplastic panels in compliance with military and
space regulations.
[0022] Referring to FIG. 1, a superplastic panel 100 constructed in
accordance with an example embodiment is illustrated. Superplastic
panel 100 includes a first face sheet 110, a second face sheet 120
spaced apart from the first face sheet 110, and a core sheet 130.
The first face sheet 110, the second face sheet 120, and the core
sheet 130 form a multi-layered structure 140.
[0023] While the multi-layered structure 140 of the superplastic
panel 100 is shown and described having three layers (i.e., the
first face sheet 110, the second face sheet 120, and the core sheet
130), additional layers, such as additional core sheets, additional
face sheets and/or additional other sheets, may be included in the
layered structure 140 without departing from the scope of the
present disclosure.
[0024] The core sheet 130 of the superplastic panel 100 includes a
first major side 131 and an opposed second major side 132. The
first face sheet 110 may be connected (e.g., adhered, welded,
braised, mechanically fastened etc.) to the first major side 131 of
the core sheet 130 and the second face sheet 120 may be connected
(e.g., adhered, welded, braised, mechanically fastened etc.) to the
second major side 132 of the core sheet 130, thereby sandwiching
the core sheet 130 between the first face sheet 110 and the second
face sheet 120, and forming the layered structure 140.
[0025] Compositionally, each of the first and second face sheets
110, 120 of the superplastic panel 100, which may be single ply or
multi-ply, may be formed from various materials or combinations of
materials. The composition of each of the first and second face
sheets 110, 120 may be the same as, similar to, or different from
the composition of the core sheet 130. As one example, each of the
first and second face sheets 110, 120 may be formed from a metal or
metal alloy, such as steel, titanium, a titanium alloy, aluminum or
an aluminum alloy. As another example, each of the first and second
face sheets 110, 120 may be formed from a composite, such as a
carbon fiber-reinforced composite or a fiberglass composite. As yet
another example, each of the first and face sheets 110, 120 may be
formed from a ceramic material. The composition of the first face
sheet 110 may be the same as, similar to, or different from the
composition of the second face sheet 120.
[0026] Each of the first and second face sheets 110, 120 is made of
a material having a thermal expansion that is different from the
thermal expansion of the other face sheet. The material of the
first face sheet 110 comprises a low thermal expansion material,
and the material of the second face sheet 120 comprises a high
thermal expansion material. In some embodiments, the material of
the first face sheet 110 comprises an iron alloy comprising 35.0
weight percent (wt %) to 40.0 wt % nickel, 12.0 wt % to 16.0 wt %
cobalt, 4.3 wt % to 5.2 wt % niobium, and 1.3 wt % to 1.8 wt %
titanium, commonly known as INCOLOY.RTM. Alloy 909. In some
embodiments, the material of the second face sheet 120 comprises a
nickel alloy comprising at least 58.0 wt % nickel, 20.0 wt % to
23.0 wt % chromium, at most 5.0 wt % iron, 8.0 wt % to 10.0 wt %
molybdenum, and 3.15 wt % to 4.15 wt % niobium, commonly known as
INCONEL.RTM. Alloy 625. INCOLOY and INCONEL are trademarks of
Special Metals Corporation.
[0027] In some embodiments, the first face sheet 110 has a
coefficient of thermal expansion between about 4.0
parts-per-million per degrees Fahrenheit (ppm/.degree. F.) and
about 5.5 ppm/.degree. F. The first face sheet 110 has a thickness
between about 0.01 inches (0.025 centimeters) and about 0.125
inches (0.318 centimeters). The first face sheet 110 has a density
between about 0.25 lbs/in.sup.3 and about 0.40 lbs/in.sup.3.
[0028] In some embodiments, the second face sheet 120 has a
coefficient of thermal expansion between about 7 ppm/.degree. F.
and about 10 ppm/.degree. F. The second face sheet 120 has a
thickness between about 0.01 inches (0.025 centimeters) and about
0.125 inches (0.318 centimeters). The second face sheet 120 has a
density between about 0.25 lbs/in.sup.3 and about 0.40
lbs/in.sup.3.
[0029] In some embodiments, the core sheet 130 has a coefficient of
thermal expansion between about 7 ppm/.degree. F. and about 10
ppm/.degree. F. The core sheet 130 is intercoupled between the
first face sheet 110 and the second face sheet 120. The core sheet
130 has a thickness between about 0.01 inches (0.025 centimeters)
and about 0.10 inches (0.254 centimeters). The core sheet 130 has a
density between about 0.25 lbs/in.sup.3 and about 0.40
lbs/in.sup.3. An example core sheet material is commercially
available as part number CarTech.RTM. 625 Alloy. CarTech is a
trademark of Carpenter Technology Corporation. Other materials that
can be used for the core sheet 130 are possible.
[0030] In some embodiments, the cross-sectional thickness of the
core sheet 130 may be relatively thick, as compared to the
cross-sectional thickness of the first face sheet 110 and the
cross-sectional thickness of the second face sheet 120. In some
embodiments, despite being relatively thick, the core sheet 130 has
a relatively lower density (basis weight divided by cross-sectional
thickness), as compared to the densities of the first face sheet
110 and the second face sheet 120.
[0031] Referring to FIG. 2, an example thermal expansion profile
200 of suitable materials (i.e., for the first and second face
sheets 110, 120) that can be used to make the superplastic panel
100 of FIG. 1 is illustrated. First solid diagonal line 210
represents the lower thermal expansion of the first face sheet 110,
and second solid diagonal line 220 represents the higher thermal
expansion of the second face sheet 120. Dashed horizontal line 230
intersects the second diagonal line 220 at a lower temperature
T.sub.1, and intersects the first diagonal line 210 at a higher
temperature T.sub.2. The difference between the higher temperature
T.sub.2 and the lower temperature T.sub.1 is up to 800.degree.
F.
[0032] The combination of the first face sheet 110, the second face
sheet 120, and the core sheet 130 cooperate to enable superplastic
panel 100 to withstand a temperature up to or above 1000.degree. F.
without degradation of the superplastic panel 100 when the first
face sheet 110 is exposed to more heat than the second face sheet
120, such as when the superplastic panel 100 is installed and in
service on a thrust reverser of an aircraft engine.
[0033] Those skilled in the art will appreciate that only a portion
of the superplastic panel 100 is shown in FIG. 1, and that the
overall size and shape of the superplastic panel 100 may depend on
the end application. For example, the disclosed superplastic panel
100 may be used as a wall panel forming the inlet inner wall, fan
duct and/or exhaust nozzle of a bypass gas turbine aircraft engine
and, therefore, may be sized, shaped and contoured accordingly.
Additionally, while the superplastic panel 100 is shown in FIG. 1
as being a substantially curved structure, planar superplastic
panels, such as superplastic panel 300 shown in FIG. 3, are also
contemplated. As shown in FIG. 3, superplastic panel 300 includes
first face sheet 310, second face sheet 320, and core sheet 330
between first and second face sheets 110, 120 to form multi-layered
structure 340. Other cross-sectional profiles of superplastic
panels are possible.
[0034] The following example illustrates a method of superplastic
forming a three-sheet panel in accordance with an embodiment. The
example superplastic forming method is intended to illustrate, but
in no way limits, the scope of the invention.
[0035] Referring to FIG. 4, a flow diagram 400 is shown
illustrating an example method of superplastic forming example
superplastic three-sheet panel 100 of FIG. 1 (or example
superplastic panel 300 of FIG. 3) in accordance with an embodiment.
The superplastic forming method 400 disclosed herein may be
employed according to FAA regulations, for example. Specifications
of FAA regulations for forming superplastic panels are known and,
therefore, will not be described.
[0036] In block 402, a first face sheet made of a first thermal
expansion material is selected. In block 404, a second face sheet
made of a second thermal expansion material that is different from
the first thermal expansion material is selected. In some
embodiments, the selecting of the first face sheet made of the
first thermal expansion material includes selecting material of the
first face sheet to be a low expansion material, and the selecting
of the second face sheet made of the second thermal expansion
material that is different from the first thermal expansion
material includes selecting material of the second face sheet to be
a high expansion material.
[0037] In some embodiments, the selecting material of the first
face sheet to be a low expansion material includes selecting
material of the first face sheet to be INCOLOY Alloy 909, and the
selecting material of the second face sheet to be a high expansion
material includes selecting material of the second face sheet to be
INCONEL Alloy 625.
[0038] Then, in block 406, each of the selected first and second
face sheets is attached to a core sheet to sandwich the core sheet
between the first and second face sheets to provide a precursor
panel. In some embodiments, the core sheet is selected with a
thickness that is greater than thickness of each of the selected
first and second face sheets. In some embodiments, the material of
the core sheet is selected to be INCONEL Alloy 625. In some
embodiments, the attaching each of the selected first and second
face sheets to a core sheet to sandwich the core sheet between the
first and second face sheets to provide a precursor panel includes
welding each of the selected first and second face sheets to the
core sheet to provide the precursor panel. In block 408, the
precursor panel is processed to form the three-sheet panel. Since
the first thermal expansion material of the first face sheet and
the second thermal expansion material of the second face sheet are
different from each other, the core sheet is pulled into a desired
shape. More specifically, the differential thermal expansion of the
two materials pulls the core sheet into a desired shape. The
process then ends.
[0039] Referring to FIG. 5, a flow diagram 500 is shown
illustrating a method of superplastic forming example superplastic
three-sheet panel 100 of FIG. 1 (or example superplastic panel 300
of FIG. 3) in accordance with another embodiment. The superplastic
forming method 500 disclosed herein may be employed according to
military and space regulations, for example.
[0040] In block 502, a first face sheet made of INCOLOY Alloy 909
is selected. In block 504, a second face sheet made of INCONEL
Alloy 625 is selected. In block 506, a core sheet made of INCONEL
Alloy 625 is selected. Then, in block 508, each of the selected
first and second face sheets is attached to the core sheet to
sandwich the core sheet between the first and second face sheets to
provide a precursor panel. In block 510, the precursor panel is
processed to form the three-sheet panel. Since the first face sheet
is made of INCOLOY Alloy 909 and the second face sheet is made of
INCONEL Alloy 625, the core sheet is pulled into a desired shape.
More specifically, the differential thermal expansion of the
INCOLOY Alloy 909 and the INCONEL Alloy 625 pulls the core sheet
into a desired shape. The process then ends.
[0041] Referring to FIG. 6, a flow diagram 600 is shown
illustrating a method of superplastic forming example superplastic
three-sheet panel 100 of FIG. 1 (or example superplastic panel 300
of FIG. 3) in accordance with yet another embodiment. The
superplastic forming method 600 disclosed herein may be employed
according to military and space regulations, for example.
[0042] In block 602, a first face sheet and a second face sheet are
attached to a core sheet to sandwich the core sheet between the
first and second face sheets. Then, in block 604, the first face
sheet is superplastic formed at a different rate of expansion than
the second face sheet to form the three-sheet panel. In some
embodiments, the superplastic forming the first face sheet at a
different rate of expansion than the second face sheet to form the
three-sheet panel includes expanding one of the first and second
face sheets at a first time and then expanding the other one of the
first and second face sheets at a second time which is after the
first time to pull the core sheet into a desired shape. In some
embodiments, the superplastic forming the first face sheet at a
different rate of expansion than the second face sheet to form the
three-sheet panel includes expanding the first and second face
sheets at the same time to pull the core sheet into a desired
shape.
[0043] The above-described example superplastic forming methods may
be carried out using manufacturing systems or apparatus suitable
for making multilayer structures such as three-sheet panels.
Numerous manufacturing systems or apparatus for making three-sheet
panels are known and, therefore, will not be described.
[0044] Examples of the present disclosure may be described in the
context of an aircraft manufacturing and service method 700 as
shown in FIG. 7 and an aircraft 800 as shown in FIG. 8. During
pre-production, the illustrative method 700 may include
specification and design, as shown at block 702, of the aircraft
800 and material procurement, as shown at block 704. During
production, component and subassembly manufacturing, as shown at
block 706, and system integration, as shown at block 708, of the
aircraft 800 may take place. Thereafter, the aircraft 800 may go
through certification and delivery, as shown block 710, to be
placed in service, as shown at block 712. While in service, the
aircraft 800 may be scheduled for routine maintenance and service,
as shown at block 714. Routine maintenance and service may include
modification, reconfiguration, refurbishment, etc. of one or more
systems of the aircraft 800.
[0045] Each of the processes of illustrative method 700 may be
performed or carried out by a system integrator, a third party,
and/or an operator (e.g., a customer). For the purposes of this
description, a system integrator may include, without limitation,
any number of aircraft manufacturers and major-system
subcontractors; a third party may include, without limitation, any
number of vendors, subcontractors, and suppliers; and an operator
may be an airline, leasing company, military entity, service
organization, and so on.
[0046] As shown in FIG. 8, the aircraft 800 produced by
illustrative method 700 (FIG. 7) may include an airframe 802 with a
plurality of high-level systems 804 and an interior 806. Examples
of high-level systems 804 may include one or more of propulsion
system 808, electrical system 810, hydraulic system 812, and
environmental system 814. Any number of other systems may be
included. Superplastic panels and superplastic forming methods
shown or described herein may be employed in any combination of
these systems.
[0047] Moreover, superplastic panels and superplastic forming
methods shown or described herein may be employed during any one or
more of the stages of the manufacturing and service method 700. For
example, components or subassemblies corresponding to component and
subassembly manufacturing (block 706) may be fabricated or
manufactured in a manner similar to components or subassemblies
produced while aircraft 800 is in service (block 712). Also, one or
more examples of superplastic panels and superplastic forming
methods, or combination thereof, may be utilized during production
stages (blocks 708 and 710). Similarly, one more examples of
superplastic panels and superplastic forming methods, or a
combination thereof, may be utilized, for example and without
limitation, while aircraft 800 is in service (block 712) and during
maintenance and service stage (block 714).
[0048] It should be apparent that a superplastic panel produced in
accordance with above-described example methods is suitable for any
type of application. The superplastic panel is especially
advantageous when there is a thermal gradient during use of the
superplastic panel, such as in a thrust reverser of an aircraft
engine, for example. The difference in thermal expansion between
the inner face sheet (i.e., the inner wall with the lower thermal
expansion coefficient and closer to the aircraft engine) and the
outer face sheet (i.e., the outer wall with the higher thermal
expansion coefficient and farther away from the aircraft engine)
reduces thermally induced stress in the superplastic panel. As
such, the superplastic panel is capable of operating at higher
temperatures with reduced thermally induced stress. The result is a
superplastic panel that does not need to be replaced as often due
to potential delamination of the inner and outer face sheets. This
lowers maintenance and service costs.
[0049] It should also be apparent that the difference in thermal
expansion between the first and second face sheets 110, 120 of the
superplastic panel 100 eliminates the need for a thick laminate of
the first face sheet 110. This is because the thermal stress
induced in the first face sheet 110 is reduced due to the lower
thermal expansion of the first face sheet 110. The result is a
weight-efficient superplastic panel (as compared to known
superplastic panels) with a capability to handle temperatures up to
or above 1000.degree. F. without degradation of the superplastic
panel when the superplastic panel is installed and in service in a
particular application. Accordingly, the superplastic panel 100 has
not only high-temperature capability, but also has low weight
(i.e., weight-competitive).
[0050] It should further be apparent that the material of the first
face sheet 110 and the material of the second face sheet 120 of the
superplastic panel 100 can each be selected and tailored to reduce
thermally induced stress in the superplastic panel 100 depending
upon the particular application of the superplastic panel (e.g., in
an inner wall/outer wall of a thrust reverser of an aircraft
engine).
[0051] Although an aerospace example is shown, the principles
disclosed herein may be applied to other industries, such as the
automotive industry, the marine industry, and the construction
industry. Accordingly, in addition to the aircraft 800, the
principles disclosed herein may apply to other vehicles (e.g., land
vehicles, marine vehicles, space vehicles, etc.) as well as to
other types of structures.
[0052] Although the above description describes a three-layer
structure in which the middle layer comprises a core sheet
construction, it is conceivable that the middle layer may comprise
a construction that is other than a core sheet. As an example, the
middle layer may comprise a brazed honeycomb construction. Other
constructions of the middle layer of the three-layer structure are
possible.
[0053] Although the above description describes example
superplastic panels and example methods of superplastic forming
three-sheet panels for OEMs in accordance with military and space
regulations, it is conceivable that the example superplastic panels
and superplastic forming methods may be implemented in any industry
in accordance with the applicable industry standards.
[0054] Also, although the above description describes a
superplastic forming method to make a three-sheet panel, it is
conceivable that other forming methods may be used.
[0055] Further, although various embodiments of the disclosed
superplastic panels and superplastic forming methods have been
shown and described, modifications may occur to those skilled in
the art upon reading the specification. The present application
includes such modifications and is limited only by the scope of the
claims.
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