U.S. patent application number 11/601205 was filed with the patent office on 2013-09-26 for simple cmc fastening system.
The applicant listed for this patent is Connie E. Bird, Lisa A. Prill. Invention is credited to Connie E. Bird, Lisa A. Prill.
Application Number | 20130251446 11/601205 |
Document ID | / |
Family ID | 39145386 |
Filed Date | 2013-09-26 |
United States Patent
Application |
20130251446 |
Kind Code |
A1 |
Bird; Connie E. ; et
al. |
September 26, 2013 |
SIMPLE CMC FASTENING SYSTEM
Abstract
A simple ceramic matrix composite fastening system that is
utilized for attaching components of dissimilar materials,
particularly, ceramic matrix composites (CMCs) and metallic engine
components. The system is comprised of a detachable subassembly
bracket fabricated from metal. The bracket has a metallic engine
component attached to one end and a CMC component attached to the
other end. The bracket releasably secures the CMC and the metallic
component together using rivets or pins, which are inserted into
holes through the CMC to securely fasten the adjoining parts.
Inventors: |
Bird; Connie E.; (Rocky
Hill, CT) ; Prill; Lisa A.; (Glastonbury,
CT) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Bird; Connie E.
Prill; Lisa A. |
Rocky Hill
Glastonbury |
CT
CT |
US
US |
|
|
Family ID: |
39145386 |
Appl. No.: |
11/601205 |
Filed: |
November 17, 2006 |
Current U.S.
Class: |
403/220 |
Current CPC
Class: |
Y10T 403/21 20150115;
F23R 3/007 20130101; F23R 3/60 20130101; F16B 2001/0085 20130101;
Y10T 403/217 20150115; F16B 5/0635 20130101; Y10T 403/45 20150115;
F16F 15/04 20130101; Y10T 403/213 20150115 |
Class at
Publication: |
403/220 |
International
Class: |
F16F 15/04 20060101
F16F015/04 |
Claims
1. An apparatus for fastening a ceramic matrix composite (CMC) to a
non-ceramic matrix component, said apparatus comprising: a
detachable subassembly bracket having a configuration with a
plurality of apertures therethrough; a plurality of fasteners
receivable through said apertures; and a spring; said spring
adapted to be inserted in a slot between said bracket and said
ceramic matrix composite; said spring capable of dampening
vibrations, wherein said bracket has a first end that is adapted to
be in direct contact with the ceramic matrix composite via said
fasteners and has a second end that is adapted to be secured to the
non-ceramic matrix component.
2. (canceled)
3. The apparatus of claim 1, wherein said plurality of apertures
are adapted to be in registration with a plurality of apertures in
said ceramic matrix composite
4. (canceled)
5. The apparatus of claim 3, wherein said plurality of fasteners
are a plurality of rivets; said rivets are adapted to be inserted
into said apertures in the ceramic matrix composite and said
apertures in the bracket to releasably fasten the ceramic matrix
composite to the bracket.
6. The apparatus of claim 5, wherein said rivets are adapted to be
installed inside of a sleeve prior to being inserted through the
apertures in the ceramic matrix composite.
7. The apparatus of claim 5, wherein said rivets are single flare
end rivets.
8. (canceled)
9. The apparatus of claim 1, wherein said non-ceramic matrix
component is metallic.
10. (canceled)
11. The apparatus of claim 1, wherein said bracket has a bridge
clamp mechanism connected thereto.
12. The apparatus of claim 1, wherein said plurality of apertures
through said bracket are elongate or round in shape.
13. (canceled)
14. An apparatus for fastening a ceramic matrix composite (CMC) to
a metallic engine component, said apparatus comprising: a
detachable subassembly bracket having a configuration with a
plurality of apertures and a slot therethrough; a plurality of
fasteners receivable in said apertures and through said slot; and a
spring; said spring adapted to be inserted in said slot between
said bracket and said ceramic matrix composite; said spring capable
of dampening vibrations, wherein said bracket is adapted to be
received by said ceramic matrix composite in said slot at one end;
said ceramic matrix composite adapted to be secured to said bracket
via said plurality of fasteners; said bracket being adapted to be
secured to the metallic engine component at an opposite end.
15. (canceled)
16. The apparatus of claim 14, further comprising a plurality of
apertures that are adapted to be aligned through apertures in said
ceramic matrix composite.
17. The apparatus of claim 14, wherein said plurality of fasteners
are a plurality of single flare end rivets; said rivets being
receivable in said apertures through said bracket and said
apertures through said ceramic matrix composite to releasably
fasten said bracket to said ceramic matrix composite.
18. The apparatus of claim 17, wherein said rivets are adapted to
be installed inside of a sleeve prior to being inserted through the
apertures in the ceramic matrix composite.
19-20. (canceled)
21. The apparatus of claim 14, wherein said bracket has a bridge
clamp mechanism connected thereto.
22. The apparatus of claim 14, wherein said apertures through said
bracket are elongate or round.
23. (canceled)
24. (canceled)
25. The apparatus of claim 14 wherein said spring is a wave
spring.
26-28. (canceled)
29. The apparatus of claim 1 wherein said spring is a wave
spring.
30-31. (canceled)
32. An apparatus for fastening a ceramic matrix composite (CMC) to
a metallic engine component, said apparatus comprising: a
detachable subassembly bracket having a configuration with an
aperture and a slot therethrough; a fastener receivable in said
aperture and through said slot; and a spring; said spring adapted
to be inserted in said slot between said bracket and said ceramic
matrix composite; said spring capable of dampening vibrations,
wherein said bracket is adapted to be received by said ceramic
matrix composite in said slot at one end; said fastener is adapted
to secure said ceramic matrix composite in said bracket thereby;
and said bracket being adapted to be secured to the engine
component at an opposite end thereof.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to an apparatus used to fasten
ceramic matrix composites (CMCs) to metallic components.
[0003] 2. Description of Related Art
[0004] Conventional gas turbine engines operate at harsh
environmental conditions characterized by high temperatures, high
pressures and intense mechanical and acoustic vibrations. Engine
manufacturers are in search of new advanced materials that are
capable of providing improved durability, greater thrust, longer
life, and superior overall performance to replace current state of
the art nickel based superalloys. Those skilled in the art of
manufacturing engines have identified ceramic matrix composites
(CMCs) as having qualities that far surpass the performance
capabilities of nickel based superalloys. CMCs can withstand higher
temperature conditions, have greater weight reduction capabilities
and improved durability over other state of the art materials. CMCs
have especially good vibrational damping capabilities and a low
coefficient of thermal expansion.
[0005] While CMCs do have many advantages, they also present design
challenges, especially in their application to hot section engine
components. These limitations make it difficult to design fastening
systems to attach CMCs to metallic engine components. Most
traditional CMCs fastening systems are unable to withstand or
dissipate heavy loads and their design often leads to space
constraints on the rest of the engine system. One such fastening
system uses a combination of screw and rivet technology. This
fastening method unavoidably leaves machined holes in the CMC.
These holes can result in stress concentrations and increase the
likelihood of CMC fracture.
[0006] Another method of fastening CMCs to metallic engine
components is a CMC self-sealing approach where oxygen entering the
engine is consumed in the CMC microcracks. This method prevents
access to the carbon matrix interface creating a sealcoat but the
sealcoat is prone to degradation. This fastening system does have a
high degree of damage tolerance however, it is not enough to
sustain the heavy loads and high temperatures that exist during
engine assembly.
[0007] Accordingly, there is a need for a fastening apparatus that
can overcome, alleviate, and/or mitigate one or more of the
aforementioned and other deleterious effects of prior art. A novel
apparatus is needed that will reduce space constraints, dampen
mechanical and acoustic vibrations, compensate for the mismatch in
thermal expansion between CMC and metal, and be able to sustain
and/or dissipate extreme acoustic, thermal and weight bearing loads
that are often not withstandable using traditional apparatuses.
SUMMARY OF THE INVENTION
[0008] The present invention provides a simple CMC fastening system
that connects CMCs to a non-CMC component. The system has a
detachable subassembly bracket that has a slotted configuration
with a plurality of holes therethrough. A plurality of fasteners
are received through the holes to hold the bracket in place. One
end of the bracket is secured to the CMCs via the fasteners and the
other end is secured to a non-CMC component.
[0009] The above-described and other features and advantages of the
present disclosure will be appreciated and understood by those
skilled in the art from the following detailed description,
drawings, and appended claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] FIG. 1 illustrates a perspective view of the first
embodiment of the simple CMC fastening system design of the present
invention;
[0011] FIG. 2 illustrates a perspective view of the second
embodiment of the simple CMC fastening system design of the present
invention using a compliant bracket; and
[0012] FIG. 3 illustrates a cross sectional view of the simple CMC
fastening system of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
[0013] Referring to the drawings and in particular FIG. 1, there is
shown the first embodiment of the CMC fastening system of the
present invention, generally represented by reference numeral 10.
Fastening system 10 has a rigid, slotted bracket 14 that tightly
straddles a CMC 18. An opposite end 30 of the bracket is attached
to a bridge clamp 12. Bridge clamp 12 is secured to bracket 14
using a nut 28 attached to a threaded post on top of bracket 14.
Bracket 14 is preferably fabricated from metal. Bracket 14 may be
fastened to CMC 18 using either a single point attachment or a
multi-point attachment.
[0014] Bracket 14 and CMC 18 have a plurality of apertures 32 and
20, respectively, through which a plurality of rivets 26 are
inserted to function as fasteners. Apertures 32 and 20 are
elongated in shape which allows for axial expansion of the system
overall.
[0015] Rivets 26 are inserted through bracket apertures 32 and CMC
apertures 20. Rivets 26 function as fasteners that securely connect
bracket 14 to CMC 18 and hold bracket 14 in position. Preferably,
rivets 26 are flared end rivets to minimize the stress induced in
the bracket and CMC apertures that would occur if a regular rivet
were used. A regular rivet would expand after installation to fill
the hole, and damage the CMC. The flared end rivet functions more
like a pin, and secures the hardware without adding the extra
stress that a traditional rivet would. Alternatively, rivets 26 may
be substituted with pins that would also function to securely
connect bracket 14 to CMC 18 and hold bracket 14 in position.
[0016] Rivets 26 may be installed inside of a plurality of optional
sleeves 22 before being inserted into bracket apertures 32 and CMC
apertures 20. The function of sleeve 22 is to prevent any stress or
damage from being induced in the edges of CMC apertures 20.
[0017] A leaf spring 16 is inserted at the point where bracket 14
and CMC piece 18 converge. The purpose of leaf spring 16 is to
dampen mechanical vibrations and to compensate for slack induced
due to clearance between the mating parts.
[0018] FIG. 2 illustrates a second embodiment of the present
invention generally shown by reference numeral 46. Elements of the
first embodiment are substantially identical to the second
embodiment except where indicated. The second embodiment of the CMC
fastening system has an alternative bracket design 36. Bracket 36
is a compliant bracket that has a vertical gap 42 which allows
bracket 36 to flex. The flexibility allows a plurality of apertures
38 in the CMC and a plurality of apertures 48 in the bracket to
line up when the parts are hot. Compliant bracket 36 reduces the
impact of the differences in coefficients of thermal expansion of
the CMC and the metal bracket. If the metal bracket and the CMC are
at the same temperature, the distance between the apertures in the
bracket will increase more than the distance between the apertures
in the CMC and therefore, can induce stress into the CMC.
[0019] If the bracket is very compliant, apertures 38 in the CMC
and apertures 48 in the bracket can be round in shape. It the
bracket is moderately compliant, apertures 38 in the CMC and
apertures 48 in the bracket can be elongated as in the first
embodiment, but the degree of elongation will be less than in the
first embodiment because of the compliant design of bracket 36.
[0020] FIG. 3 illustrates a cross sectional view of the CMC
fastening system of the present invention, generally represented by
reference numeral 70. Fastening system 70 has a first sleeve 80 and
a second sleeve 72 that capture a single flare end rivet 78.
Alternatively, rivet 78 may be a standard rivet or a double
countersunk rivet. A Belleville washer 74 and a washer/shim 76 may
be used on one or both sides of a CMC rib 82 to maintain a tight
fit during engine operation.
[0021] Both the first and second embodiments of the CMC fastening
system may require additional parts if there is a substantial
discrepancy between the coefficient of thermal expansion of the CMC
and the metallic engine component attachment. The fastening system
can achieve thermal expansion using a spring if necessary. Any such
discrepancy upon expansion of the metal when the CMC does not
expand along the length of the rivet can be compensated for using
additional springs, such as a Belleville washer(s) or wave springs.
The Belleville washer can be placed between the nut and the feature
to maintain when the parts thermally expand. The washer can serve
the additional purpose of reducing the stiffness of the fastener
assembly to minimize CMC stress that tends to build because of
thermally induced tightening of the assembly.
[0022] Both embodiments of the CMC fastening system and of the
current invention may use either a single or multi-point
attachment, although a single point attachment would not use a
compliant bracket. Single point attachment is preferred where the
load bearing capability of the material is above the applied load.
In the case of a multi-point attachment, a design feature can be
added that allows compliance as needed. If a single point
attachment is utilized and rotational freedom is required, the
springs may be adjusted in size or eliminated entirely, depending
on the specification requirements.
[0023] While the present disclosure has been described with
reference to one or more exemplary embodiments, 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 present disclosure. In
addition, many modifications may be made to adapt a particular
situation or material to the teachings of the invention without
departing from the scope thereof. Therefore, it is intended that
the present disclosure not be limited to the particular
embodiment(s) disclosed as the best mode contemplated, but that the
disclosure will include all embodiments falling within the scope of
the appended claims.
* * * * *