U.S. patent application number 10/903419 was filed with the patent office on 2006-03-23 for repair method for noise suppression structure.
Invention is credited to Vincent Chung, James F. Stevenson, Ion Virgil Vintilescu, Roger B. Williamson.
Application Number | 20060059828 10/903419 |
Document ID | / |
Family ID | 36072397 |
Filed Date | 2006-03-23 |
United States Patent
Application |
20060059828 |
Kind Code |
A1 |
Stevenson; James F. ; et
al. |
March 23, 2006 |
Repair method for noise suppression structure
Abstract
A method is provided for repairing a defect in a noise
suppression panel. The method may be used to repair defects in a
panel that may occur during the manufacture of or normal use of the
panel. The method includes the steps of removing the defect from
the noise suppression panel to create a cavity therein, forming
material comprised of a material having acoustic damping properties
into an insert configured to mate with the cavity, and placing the
insert into the cavity.
Inventors: |
Stevenson; James F.;
(Morristown, NJ) ; Williamson; Roger B.;
(Flanders, NJ) ; Vintilescu; Ion Virgil; (Phoenix,
AZ) ; Chung; Vincent; (Tempe, AZ) |
Correspondence
Address: |
HONEYWELL INTERNATIONAL INC.
101 COLUMBIA ROAD
P O BOX 2245
MORRISTOWN
NJ
07962-2245
US
|
Family ID: |
36072397 |
Appl. No.: |
10/903419 |
Filed: |
July 29, 2004 |
Current U.S.
Class: |
52/514 |
Current CPC
Class: |
F02C 7/045 20130101;
F05D 2220/50 20130101; F05D 2260/96 20130101; B29C 73/26 20130101;
Y02T 50/60 20130101; F01D 5/005 20130101; E04G 23/0207 20130101;
Y02T 50/672 20130101; F05D 2230/80 20130101; B29C 73/06
20130101 |
Class at
Publication: |
052/514 |
International
Class: |
E02D 37/00 20060101
E02D037/00 |
Claims
1. A method for repairing a defect in a noise suppression panel,
the method comprising: removing a section of the noise suppression
panel that includes the defect to thereby create a cavity in the
panel; forming an insert configured to mate with the cavity from a
material having acoustic damping properties; and placing the insert
at least partially within the cavity.
2. The method of claim 1, wherein the cavity and the insert each
have a sidewall and the method further comprises: applying a
bonding agent to at least one of the sidewalls; and adhering the
insert sidewall and cavity sidewall to one another.
3. The method of claim 2, wherein the bonding agent comprises one
of epoxy, silicone adhesive, and ceramic cement.
4. The method of claim 1, wherein the cavity and insert are each
cylindrically-shaped.
5. The method of claim 1, wherein the cavity and insert are each
beveled.
6. The method of claim 1, wherein the cavity and insert are each
stepped.
7. The method of claim 1, wherein the cavity and insert are each
threaded.
8. The method of claim 1, wherein the panel comprises a back plate,
the method further comprising: bonding the insert to the back
plate.
9. The method of claim 1, wherein the defect is removed by, and the
insert is formed using, a circular saw.
10. The method of claim 1, wherein the defect is removed from the
panel using a contoured cutting tool.
11. The method of claims 1 further comprising machining threads
into the cavity and insert.
12. The method of claim 1, wherein the noise suppression panel and
acoustic damping material are the same material.
13. The method of claim 12, wherein the acoustic damping material
comprises one of an open cell foam bulk absorber material and a
high temperature honeycomb material.
14. The method of claim 1, wherein the noise suppression panel has
a first and a second side, the method further comprising: bonding a
back plate to the first side of the noise suppression panel.
15. The method of claim 14, wherein the back plate comprises a
non-porous material.
16. The method of claim 14, further comprising: bonding a face
plate to the second side of the noise suppression panel.
17. The method of claim 16, wherein the face plate comprises a
material that is perforated to a percent open area (POA) value
greater than 30%.
18. The method of claim 16, wherein the face plate comprises a
screen.
19. A method for repairing a defect in a noise suppression panel
having a back plate, a face plate and a bulk absorber disposed
therebetween, the method comprising: removing at least a portion of
the face plate; removing a section of the noise suppression panel
that includes the defect to thereby create a cavity in the panel;
forming an insert configured to mate with the cavity from a
material having acoustic damping properties; placing the insert
into the cavity; and bonding the insert to the back plate.
20. The method of claim 19, wherein the acoustic damping material
comprises one of an open cell foam bulk absorber material and a
high temperature honeycomb material.
21. The method of claim 19, wherein the bulk absorber and acoustic
damping material are the same material.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to noise suppression
structures and, more particularly, to noise suppression structures
for aircraft ducts and plenums, and methods of repairing the
structures.
BACKGROUND OF THE INVENTION
[0002] Many aircraft are powered by jet engines. In most instances,
jet engines include one or more gas-powered turbine engines,
auxiliary power units (APUs), and/or environmental control systems
(ECSs), which can generate both thrust to propel the aircraft and
electrical energy to power systems installed in the aircraft.
Although most aircraft engines are generally safe, reliable, and
efficient, the engines do exhibit certain drawbacks. For example,
the turbine engines, as well as other components that make up the
engine, can be sources of unwanted noise, especially during
aircraft take-off and landing operations. Moreover, APUs and ECSs
can be sources of unwanted ramp noise. Thus, various governmental
rules and regulations aimed at mitigating such noise sources have
been enacted.
[0003] To address, and at least somewhat alleviate, the unwanted
noise emanating from aircraft noise sources, and to thereby comply
with the above-noted rules and regulations, various types of noise
reduction treatments have been developed. For example, one type of
noise reduction treatment that has been developed for use in
aircraft ducts is a noise suppression panel. In many instances,
noise suppression panels are flat or contoured, and include a
honeycomb structure disposed between a backing plate and a face
plate. Other noise suppression materials and structure may also be
disposed between the backing plate and face plate. The noise
suppression panels are typically placed on the interior surface of
engine or APU inlet and/or outlet plenums, as necessary, to reduce
noise emanations.
[0004] Periodically, these noise suppression panels may become
damaged from normal wear. Voids may form in the panel, or
alternatively, air gaps between the face plate and honeycomb
structure may appear. Conventionally, the repair of these damaged
sections include, for example, applying liquid resin to the voids
or air gaps and subsequent curing of the panel. Other repair
methods have included filling the voids or damaged sections with a
clay-like substance. However, neither cured resins nor clay have
acoustic damping properties, and thus, can reduce, rather than
maintain or enhance, the noise suppression capabilities of the
panel.
[0005] The foam core material in the noise suppression panels may
contain manufacturing defects, such as voids or uneven surfaces. In
these cases, the defective panels may not operate as intended and
have historically been entirely discarded. As a result, the costs
of aircraft manufacture and/or maintenance may increase.
[0006] Hence, there is a need for a method of repairing a noise
suppression panel that restores the noise suppression capabilities
of the panel to its original specifications, and/or is less costly
compared to known methods, and/or maintains noise suppression
capabilities over a relatively wide frequency range. The present
invention addresses one or more of these needs.
SUMMARY OF THE INVENTION
[0007] A method is provided for repairing a defect in a noise
suppression panel.
[0008] In one embodiment, and by way of example only, first, a
section of the noise suppression panel that includes the defect is
removed to thereby create a cavity in the panel. Next, an insert
configured to mate with the cavity is formed from a material having
acoustic damping properties. Then, the insert is placed at least
partially within the cavity.
[0009] In another exemplary embodiment, a method is provided for
repairing a defect in a noise suppression panel having a back
plate, a face plate and a bulk absorber disposed therebetween. The
method includes removing at least a portion of the face plate,
removing a section of the noise suppression panel that includes the
defect to thereby create a cavity in the panel, forming an insert
configured to mate with the cavity from a material having acoustic
damping properties, placing the insert into the cavity, and bonding
the insert to the back plate.
[0010] Other independent features and advantages of the preferred
method will become apparent from the following detailed
description, taken in conjunction with the accompanying drawings
which illustrate, by way of example, the principles of the
invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] FIG. 1 is a simplified perspective view of a noise
suppression panel according to an exemplary embodiment of the
present invention;
[0012] FIG. 2 is a perspective view of an exemplary damaged noise
suppression panel;
[0013] FIG. 3 is a perspective view of another exemplary damaged
noise suppression panel;
[0014] FIG. 4 is a simplified schematic representation of one step
of an exemplary process for repairing the noise suppression panel
of FIGS. 1-3, according to one embodiment of the present
invention;
[0015] FIG. 5 is a simplified schematic representation of another
step of an exemplary process for repairing the noise suppression
panel of FIGS. 1-3, according to one embodiment of the present
invention;
[0016] FIGS. 5A and 5B are cross sectional views of the noise
suppression panel illustrated in FIG. 5 taken along lines 5A,
5B-5A, 5B;
[0017] FIG. 6 is a simplified schematic representation of yet
another step of an exemplary process for repairing the noise
suppression panel of FIGS. 1-3, according to one embodiment of the
present invention;
[0018] FIG. 6A is an exemplary insert that may be used in the step
depicted in FIG. 6;
[0019] FIG. 6B is another exemplary insert that may be used in the
step depicted in FIG. 6;
[0020] FIG. 7 is a simplified schematic representation of still yet
another step of an exemplary process for repairing the noise
suppression panel of FIGS. 1-3, according to one embodiment of the
present invention;
[0021] FIGS. 7A and 7B are cross sectional views of the noise
suppression panel illustrated in FIG. 7 taken along lines 7A,
7B-7A, 7B; and
[0022] FIG. 8 is a flowchart of an exemplary process for repairing
the noise suppression panel of FIGS. 1-3.
DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT
[0023] Before proceeding with the detailed description, it is to be
appreciated that the described embodiment is not limited to use in
conjunction with a particular type of engine, or in a particular
type of vehicle. Thus, although the present embodiment is, for
convenience of explanation, described as being implemented in an
aircraft environment, it will be appreciated that it can be
implemented in various other types of vehicles, and in various
other systems and environments.
[0024] Turning now to the description, and with reference first to
FIG. 1, an exemplary noise suppression panel 100 is depicted in
perspective and cross section, respectively. In FIG. 1, the panel
100 includes a back plate 102, a face plate 104, and a bulk
absorber 106. The back plate 102 is preferably imperforate and is
constructed of any one of numerous types of non-porous materials
such as, for example, aluminum, epoxy, or bismaleimide (BMI). As
will be described more fully below, the back plate 102 is
preferably bonded directly to the bulk absorber 106 during
manufacture of the panel 100.
[0025] The face plate 104 is constructed of any one of numerous
types of materials such as, for example, aluminum, and carbon
composites. In one exemplary embodiment, the face plate 104 is
constructed of BMI, and is perforated to a desired percent open
area (POA) value. As is generally known, relatively low POA values
(e.g., .about.5%) provide acoustic resistance, whereas relatively
high POA values (e.g., .about.30%) provide acoustic transparency.
In a particular preferred embodiment, the face plate 104 is
perforated to a POA value greater than 30% to ensure the face plate
104 is acoustically transparent to any incident sound. In another
exemplary embodiment, the face plate 104 is a screen. Similar to
the back plate 102, and as will be described further below, the
face plate 104 is also preferably bonded to the bulk absorber 106
during manufacture of the panel 100.
[0026] The bulk absorber 106 is disposed between the back plate 102
and face plate 104 and, as was mentioned above, is preferably
directly bonded to each plate 102, 104 during manufacture of the
panel 100. The bulk absorber 106 may be constructed of any one of
numerous materials, such as, for example, foamable material,
material having honeycomb cavities therein, honeycomb material
filled at least partially with epoxy for structural enhancement, or
any one of numerous other type of acoustic damping material. In one
exemplary embodiment, the bulk absorber 106 is an open cell foam
bulk absorber, such as the type disclosed in U.S. patent
application Ser. No. ______ entitled "Noise Suppression Structure
Manufacturing Method" filed on May 20, 2004 and U.S. patent
application Ser. No. ______ entitled "Noise Suppression Structure
and Method of Making Same" filed on Feb. 20, 2004.
[0027] Occasionally, during manufacture or as a result of normal
wear, the noise suppression panel 100 may become damaged or
defective. The damage may take any one of numerous forms. For
example, and as shown more clearly in FIG. 2, the bulk absorber 106
may include a void 202 that adversely affects the noise suppression
capabilities of the noise suppression panel 100. The void 202 may
extend partially or entirely through the thickness of the bulk
absorber 106. Although the void 202 is illustrated as being
proximate a corner of the panel 100, it will be appreciated that
the damage may occur at various locations on the panel 100. For
instance, the damage may be present on the edge of a panel 100,
such as a void 204 illustrated in FIG. 2. The defect may be a
shallow depression with a skin at the surface of the bulk absorber.
This type of defect may result from incomplete filling of the mold
during the manufacturing process. In another example, the defect
may be a density defect 206, which may result when the density of
one section is higher or lower than desired. In other cases, the
back plate 102 and/or face plate 104 may be damaged. As illustrated
in FIG. 3, the face plate 104 may pull apart from the bulk absorber
106 or a void 208 may appear in the bulk absorber 106.
[0028] Regardless of the particular type of defect, the bulk
absorber 106 is preferably repaired and the repair method of the
present invention is preferably employed. The overall process 500
is illustrated in FIGS. 4-8, and will first be described generally.
It should be understood that the parenthetical references in the
following description correspond to the reference numerals
associated with the flowchart blocks shown in FIG. 8. First, the
defect 402 on the bulk absorber 106 is removed to create a cavity
404 (510). Next, acoustic damping material 406 is formed into an
insert 408 that is configured to mate with the cavity 404 (520).
The insert 408 is then placed into the cavity 404 (530). In an
alternative embodiment, the insert 408 is bonded to the cavity 404
(540). These steps will now be discussed in detail below.
[0029] As briefly mentioned previously and as shown in FIGS. 4 and
5, the defect 402 is removed from the bulk absorber 106 to create a
cavity 404 (510). The cavity 404 is preferably sized larger than
the defect 402 and may be created in any one of numerous manners.
Any one of numerous shapes may be machined into the bulk absorber
106. In one exemplary embodiment, a circular saw is employed to cut
the defect 402 out of the bulk absorber 106. As a result, the
cavity 404 created has a circular shape. In another exemplary
embodiment, the bulk absorber 106 is attached to the backing plate
102, thus, the cavity 404 is formed without damaging the backing
plate 102. In yet another exemplary embodiment, the defect 402 is
removed with a contoured cutting tool and a cavity 404 having a
predetermined shape is formed in the bulk absorber 106. At least a
portion of the cutting tool may be covered with an abrasive, such
as diamond dust, so that the walls of the cavity 404 may be
smooth.
[0030] In some instances, the shape of the cavity walls 410 may
provide an improved surface to which a repair may be made. For
example, the cavity walls 410 may have a beveled (as illustrated in
FIG. 5A), stepped (as illustrated in FIG. 5B), or threaded shape.
Threaded walls may be used for threading the insert 408 into the
cavity 404 and for providing additional surface area for bonding.
In another exemplary embodiment, a flowable material, such as
epoxy, is applied to the cavity walls 410 and hardens to reinforce
the cavity walls 410. The reinforced cavity walls 410 may be used
to provide an improved surface to which to bond.
[0031] With reference to FIG. 6, once the defect 402 is removed, an
insert 408 is then formed from acoustic damping material 406 (520).
The insert 408 is preferably configured to tightly fit in the
cavity 404. In another exemplary embodiment, the insert 408 is
sized slightly larger than the cavity 404. In yet another exemplary
embodiment, the insert 408 has a thickness that is slightly greater
than the bulk absorber 106. In still yet another embodiment, the
cavity walls 410 have a beveled, stepped, or threaded shape.
Accordingly, the insert walls 412 are configured to have a shape
that mates with the beveled or stepped shape, such as shown in
FIGS. 6A and 6B, respectively.
[0032] The insert 408 can be formed by any one of numerous methods.
Some examples include, but are not limited to machining, cutting,
or chiseling the insert 408 out of the material 406. Any one of
numerous tools, such as a straight circular saw or a hole cutter
with beveled walls may be used to form the insert 408 from the
material 406. As those with skill in the art may appreciate, tools
used for forming the insert 408 and tools for creating the cavity
404 may be matched sets having a variety of graded cutter sizes
that may be useful to cover the expected range of defect sizes.
[0033] It will additionally be appreciated that the acoustic
damping material 406 may be any one of a number of materials that
suitably suppress noise to a predetermined noise level. Preferably,
the acoustic damping material 406 damps aircraft noise by between
about 5 and 10 dB, however, as appreciated by those skilled in
avionics, the acoustic damping material 406 most preferably meets
federal noise level standards mandated by the Federal Aviation
Administration. Examples of suitable materials include but are not
limited to, the bulk absorber 106 materials mentioned above,
conventional honeycomb treatments, and those materials disclosed in
U.S. patent application Ser. No. ______ entitled "Noise Suppression
Structure Manufacturing Method" filed on May 20, 2004, and U.S.
patent application Ser. No. ______ entitled "Noise Suppression
Structure and Method of Making Same" filed on Feb. 20, 2004.
[0034] The acoustic damping material 406 can be the same material
from which the bulk absorber 106 is manufactured. However, this is
not a requirement; accordingly, the acoustic damping material 406
and bulk absorber 106 material may be different materials. In one
exemplary embodiment, the acoustic damping material 406 has
mechanical properties that are at least comparable to those of the
bulk absorber 106 material to maintain the mechanical integrity of
the bulk absorber 106.
[0035] Turning now to FIG. 7, once an appropriate insert 408 is
formed, the insert 408 is placed in to the cavity 404 such that the
cavity walls 410 and insert walls 412 mate with one another (530).
In some embodiments, and as was mentioned above, the cavity walls
410 and insert walls 412 each have beveled or stepped shapes that
mate with one another and mechanically lock the insert 408 into the
cavity 404, such as illustrated in FIGS. 7A and 7B,
respectively.
[0036] As previously mentioned, in an alternative embodiment, the
insert 408 is bonded to the cavity 404 (540). Any known bonding
method and bonding agent may be implemented. For example, a bonding
agent, such as any one of numerous glues, epoxies, silicone
adhesives, or ceramic cements may be applied to the cavity walls
410, insert walls 412, or both. After the insert 408 and cavity 404
are aligned and brought into contact with one another, pressure is
applied and maintained on the bonded area until the bonding agent
has set. In an exemplary embodiment, after the insert 408 is
inserted into the cavity 404, the top and bottom surfaces of the
bulk absorber 106 panel around the insert 408 are machined down to
create a uniform surface. In another exemplary embodiment, bonding
may be employed in conjunction with mechanically locking the insert
408 into the cavity 404.
[0037] In the case where the repair process is performed on a noise
suppression panel 100 having a back plate 102, a face plate 104,
and bulk absorber 106, the face plate 104 first is removed (550).
Then, the defect 402 is removed from the bulk absorber 106 without
damaging the back plate 102. After the cavity 404 is prepared to
receive the insert 408, the insert 408 is bonded at least to the
back plate 102.
[0038] When the repair process is performed on a bulk absorber 106
panel during manufacture, after the bulk absorber 106 is repaired,
a back plate 102 is bonded to the bulk absorber 106. Alternatively,
a face plate 104 may be bonded to the bulk absorber 106 as
well.
[0039] While the invention has been described with reference to a
preferred embodiment, it will be understood by those skilled in the
art that various changes may be made and equivalents may be
substituted for elements thereof without departing from the scope
of the invention. In addition, many modifications may be made to
adapt to a particular situation or material to the teachings of the
invention without departing from the essential scope thereof.
Therefore, it is intended that the invention not be limited to the
particular embodiment disclosed as the best mode contemplated for
carrying out this invention, but that the invention will include
all embodiments falling within the scope of the appended
claims.
* * * * *