Note: Descriptions are shown in the official language in which they were submitted.
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A FRANGIBLE COMPOSITE AIRFOIL
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH
[00011 None.
PRIORITY INFORMATION AND CROSS-REFERENCE TO RELATED APPLICATIONS
100021 This application claims priority to U.S. patent application Ser. No.
14/596,841 by
Darek Zatorski, entitled "A method of manufacturing a frangible blade," the
entire contents of
which is incorporated by reference herein, U.S. patent application Ser. No.
14/596,815 by
Darek Zatorski, entitled "A rotary machine with a frangible composite blade",
the entire
contents of which is incorporated by reference herein, and U.S. patent
application Ser. No.
14/596,804 by Darek Zatorski, entitled "A frangible airfoil," the entire
contents of which is
incorporated by reference herein.
TECHNICAL FIELD
100031 The field of the present disclosure relates generally to rotary
machines, and more
particularly to airfoils used with rotary machines. The present embodiments
relate generally to
an airfoil for use in a fan module of an aircraft mounted gas turbine engine.
More specifically,
present airfoil embodiments relate to, but are not limited to, a composite fan
blade or propeller
which mitigates adverse conditions associated with release of material
resulting from impact
damage.
BACKGROUND OF THE INVENTION
100041 At least some known rotary machines, such as gas turbine engines,
some of which
are used for aircraft propulsion, include a plurality of rotating blades or
propellers that are
part of a fan module that channel air downstream. Conventional single rotation
turboprop gas
turbine engines provide high efficiency at low cruise speeds, for flight Mach
numbers up to
about 0.7, although some single rotation turboprop engines have been
considered for higher
cruise speeds. Higher cruise speeds, Mach 0.7 to 0.9, are typically achieved
using a ducted
fan gas turbine engine to produce the relatively high thrust required.
Unducted, counter-
rotating propeller gas turbine engines, frequently referred to as the unducted
fan (UDFS) a
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registered trademark of General Electric), or open-rotor, have been developed
to deliver the
high thrust required for high cruise speeds with higher efficiency than ducted
fans. These
blades and propellers have certain integrity to foreign object debris ingested
by the engine,
but the ingestion of foreign objects still can lead to releasing damaging
portions of the
rotating blade or propeller and therefore can be improved.
SUMMARY
100051 In one aspect, an embodiment of the invention relates to an airfoil
having a
composite blade with a root, tip, and span between the root and the tip, along
with a leading
edge and trailing edge with a chord between these edges, the blade having at
least one energy
dissipating member with a pouch.
100061 In another aspect, an embodiment of the invention relates to energy
dissipating
members that extend along the span and chord of the composite blade and have
at least one
strand.
100071 In other aspects, an embodiment of the invention relates to energy
dissipating
members that are partially covered with a release agent and are co-cured with
the composite
blade.
100081 In other aspects, an embodiment of the invention relates to energy
dissipating
members that have damage initiators with at least one strand coupled to the
initiator. Further,
the initiators may be a pouch. Still further, the pouch may have a plunger
conforniing to the
pouch, where the plunger works in combination with the at least one strand to
expand the
pouch, and subsequently damage or shred the composite blade.
100091 In yet another aspect, an embodiment of the invention relates to the
pouch activates
with a released portion of the composite blade separates from the composite
blade.
100101 In still another aspects, an embodiment of the invention relates to
a method of
manufacturing a frangible laminate, comprising the steps of constructing a
reinforced polymer
matrix,
100111 cutting the reinforced polymer matrix into a plurality of laminae,
forming a laminate
via stacking the plurality of laminae and at least one energy dissipating
member, and
consolidating the laminate.
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100121 In another aspect, an embodiment of the invention relates to the
method using
reinforced polymer matrix that comprises a resin wherein the resin is selected
from the group
consisting of polyetheretherketone, polyetherketoneketone, polyphenylene
sulfide,
polyamideimide, polyetherimides, epoxy, polyester, phenolic, vinyl ester,
polyurethane,
silicone, polyamide, and polyamide-imide. Similarly, an embodiment of the
invention relates
to the method wherein the reinforced polymer matrix comprises a reinforcement
wherein the
reinforcement is selected from the group consisting of glass, graphite,
aramid, and organic
fiber. Additionally, an embodiment of the invention relates to the method were
the resin further
comprises a toughening material, wherein the toughening material is selected
from the group
consisting of elastormeric rubber and thermoplastic.
100131 In other aspects, an embodiment of the invention relates to the
method where the
laminae are plies, to the method were the laminate is shaped into a final
product, and to the
method were the consolidate is performed in an autoclave.
10014) In yet another aspect, an embodiment of the invention relates to the
method were
the laminate is shaped into a final product that is a composite blade. In
another aspect, an
embodiment of the invention relates to the method shaping a final product that
is a composite
blade using reinforced polymer matrix that comprises a resin wherein the resin
is selected from
the group consisting of polyetheretherketone, polyetherketoneketone,
polyphenylene sulfide,
polyamideimide, polyetherimides, epoxy, polyester, phenolic, vinyl ester,
polyurethane,
silicone, polyamide, and polyamide-imide. Similarly, an embodiment of the
invention relates
to the method shaping a final product that is a composite blade using
reinforced polymer matrix
comprises a reinforcement wherein the reinforcement is selected from the group
consisting of
glass, graphite, aramid, and organic fiber.
100151 In still another aspects, an embodiment of the invention relates to
a method of
operating a self-shredding blade, the method comprising the steps of releasing
a released
portion of a composite blade, the composite blade comprising at least one
energy dissipating
member; damaging the released portion via the at least one energy dissipating
member;
optionally retaining a retained portion of the composite blade; and optionally
damaging the
retained portion via the at least one energy dissipating member.
100161 In another aspect, an embodiment of the invention relates to the
method of operating
a self-shredding blade, where the energy dissipating member is coupled to a
rotor.
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100171 In another aspect, an embodiment of the invention relates to the
method of operating
a self-shredding blade, wherein the damaging steps further comprise damaging
composite
blade structure surrounding the at least one energy dissipating member.
100181 In another aspect, an embodiment of the invention relates to the
method of operating
a self-shredding blade, further comprising the step of altering the trajectory
of the released
portion via the at least one energy dissipating member such that the released
portion follows a
predetermined path.
100191 In yet another aspect, an embodiment of the invention relates to the
method of
operating a self-shredding blade, further comprising the step of dissipating
the kinetic energy
of the released portion via the at least one energy dissipating member.
WM This Summary is provided to introduce a selection of concepts in a
simplified form
that are further described below in the Detailed Description. This Summary is
not intended to
identify key features or essential features of the claimed subject matter, nor
is it intended to be
used to limit the scope of the claimed subject matter. All of the above
outlined features are to
be understood as exemplary only and many more features and objectives of the
structures and
methods may be gleaned from the disclosure herein. A more extensive
presentation of features,
details, utilities, and advantages of the present invention is provided in the
following written
description of various embodiments of the invention, illustrated in the
accompanying drawings.
and defined in the appended claims. Therefore, no limiting interpretation of
the summary is to
be understood without further reading of the entire specification, claims and
drawings included
herewith.
BRIEF DESCRIPTION OF THE DRAWINGS
100211 The above-mentioned and other features and advantages of these
embodiments, and
the manner of attaining them, will become more apparent and the embodiments
will be better
understood by reference to the following description taken in conjunction with
the
accompanying drawings, wherein:
[0022i FIG. 1 is a side section view of an ducted fan gas turbine engine;
[0023] FIG. 2 is a perspective view of unducted counter-rotating propeller
engines
mounted on an aircraft;
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100241 FIG. 3 is a side view of a counter-rotating propeller engine;
100251 FIG. 4, 5, 6, and 7 are respective time sequence front views of a
ducted fan engine
during release of an fan airfoil portion;
[00261 FIG. 8 and 9 are exemplary embodiments of the invention and are side
views of a
composite blade with energy dissipating members, the blade shown in a pristine
state and
separated state respectively;
100271 FIG. 10 is an alternate exemplary embodiment of the invention and is
a side view
of a composite blade with energy dissipating members having damage initiators;
[00281 FIG. 11 is a perspective view of the damage initiators from the
exemplary
embodiment of the invention in FIG. 10.
100291 FIG. 12 and FIG. 13 are sectional cut-away views from the exemplary
embodiments
of the invention in FIG. 10 and the damage initiators of FIG. 11, in a "pre-
event" and "post-
event" condition respectively.
100301 FIG. 14 is an another exemplary alternate embodiment of the
invention and a
sectional side view of a composite blade with energy dissipating members and
release zones;
100311 FIG. 15 is an another exemplary alternate embodiment of the
invention and a side
view of composite blade with an energy dissipating member;
100321 FIG. 16, 17, 18, and 19 are respective time sequence front views of
propellers during
release of a propeller portion after an impact event; and,
100331 FIG. 20, 21, 22, and 23 are respective time sequence front views of
the exemplary
alternate embodiment of the invention of FIG. 15 during release of a portion
after an impact
event.
100341 FIG. 24 is a flow diagram which summarizes sequential process steps
carried out
according to the method of the present invention.
DETAILED DESCRIPTION
100351 It is to be understood that the depicted embodiments are not limited
in application
to the details of construction and the arrangement of components set forth in
the following
description or illustrated in the drawings. The depicted embodiments are
capable of other
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embodiments and of being practiced or of being carried out in various ways.
Each example is
provided by way of explanation, not limitation of the disclosed embodiments.
In fact, it will
be apparent to those skilled in the art that various modifications and
variations may be made in
the present embodiments without departing from the scope or spirit of the
disclosure. For
instance, features illustrated or described as part of one embodiment may be
used with another
embodiment to still yield further embodiments. Thus, it is intended that the
present disclosure
covers such modifications and variations as come within the scope of the
appended claims and
their equivalents.
100361 Also, it is to be understood that the phraseology and terminology
used herein is for
the puipose of description and should not be regarded as limiting. The use of
"including,"
"comprising," or "having" and variations thereof herein is meant to encompass
the items listed
thereafter and equivalents thereof as well as additional items. Unless limited
otherwise, the
terms "connected," "coupled," and "mounted," and variations thereof herein are
used broadly
and encompass direct and indirect connections, couplings, and mountings. In
addition, the
terms "connected" and "coupled" and variations thereof are not restricted to
physical or
mechanical connections or couplings.
100371 As used herein, the terms "axial" or "axially" refer to a dimension
along a
longitudinal axis of an engine. The term "forward" used in conjunction with
"axial" or
"axially" refers to moving in a direction toward the engine inlet, or a
component being
relatively closer to the engine inlet as compared to another component. The
term "aft" used in
conjunction with "axial" or "axially" refers to moving in a direction toward
the engine nozzle,
or a component being relatively closer to the engine nozzle as compared to
another component.
100381 As used herein, the terms "radial" or "radially" refer to a
dimension extending
between a center longitudinal axis of the engine and an outer engine
circumference. The use
of the terms "proximal" or "proximally," either by themselves or in
conjunction with the terms
"radial" or "radially," refers to moving in a direction toward the center
longitudinal axis, or a
component being relatively closer to the center longitudinal axis as compared
to another
component. The use of the terms "distal" or "distally," either by themselves
or in conjunction
with the terms "radial" or "radially," refers to moving in a direction toward
the outer engine
circumference, or a component being relatively closer to the outer engine
circumference as
compared to another component.
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100391 As used herein, the terms "lateral" or "laterally- refer to a
dimension that is
perpendicular to both the axial and radial dimensions.
100401 All directional references (e.g., radial, axial, proximal, distal,
upper, lower, upward,
downward, left, right, lateral, front, back, top, bottom, above, below,
vertical, horizontal,
clockwise, counterclockwise) are only used for identification purposes to aid
the reader's
understanding of the present invention, and do not create limitations,
particularly as to the
position, orientation, or use of the invention. Connection references (e.g.,
attached, coupled,
connected, and joined) are to be construed broadly and may include
intermediate members
between a collection of elements and relative movement between elements unless
otherwise
indicated. As such, connection references do not necessarily infer that two
elements are
directly connected and in fixed relation to each other. The exemplary drawings
are for purposes
of illustration only and the dimensions, positions, order and relative sizes
reflected in the
drawings attached hereto may vary.
[0041) Fan blades for ducted fan gas turbine engines and propellers for
single rotation
turboprop and unducted counter-rotating propeller gas turbine engines have
certain integrity to
foreign object damage from birds, debris, and other items ingested by the
engine. However,
the ingestion of foreign objects may lead to release of portions of the
rotating blade or propeller
that may cause damage to other engine components or aircraft structures. In
the case of fan
blades for single rotation turboprop and unducted counter-rotating propeller
engines, or open-
rotors, if not otherwise managed, the lack of duct structure surrounding the
blade or propeller
for these types of engines presents the opportunity for the trajectory of the
released portion of
the blade or propeller to cause the portion to impact an adjacent trailing
blade as well as other
adjacent aircraft structure. The blades and propellers of the prior art lack
frangibility to reduce
the size and energy of any released blade portions. Thus ducted, unducted
single rotation
turboprop, and unducted counter-rotating fan blades and propellers that are
resistant to foreign
object damage yet frangible when desired may be provided.
10042) A composite blade according to the present invention is described
below in detail.
As used in the brief descriptions of the illustrations, this paragraph, and
hereafter, the term
"blade" is understood to include, but is not limited to, both a fan blade and
a propeller and the
term "composite" is understood to include, but is not limited to, a reinforced
polymer matrix
composite, including matrices that are thermoset or thermoplastic and
reinforcements that
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include, but are not limited to, glass, graphite, aramid, or organic fiber of
any length, size, or
orientation and furthermore understood to include, but is not limited to,
being manufactured by
injection molding, resin transfer molding, prepreg tape layup (hand or
automated), puftrusion,
or any other suitable method for manufacture of a reinforced polymer matrix
composite
structure. Additionally "composite" is understood to include, but is not
limited to, a hybrid
composite of reinforced polymer matrix composite in combination with metal or
combinations
of more than one reinforced polymer matrix composite or combinations of more
than one metal.
The term "co-cured" may be understood to include, but is not limited to, both
the act of curing
a composite and simultaneously bonding it to some other uncured material as
well as the act of
curing together of two or more elements, of which at least one may be fully
cured and at least
one may be uncured.
[0043j The term "trajector3,7" is understood to include, but is not limited
to, the path taken
by a released portion of a composite blade after the portion is released. This
path may describe,
for example, relative to the longitudinal centerline of a rotary machine, for
example, a gas
turbine engine centerline.
100441 The composite blade may operate at high rotational speed and linear
tip speeds and
may comprise at least one of the means selected from the group consisting of,
means for
dissipating energy, means for self-shredding, and means for predetermining
release trajectory.
The composite blade may include one or more internal, co-cured, energy
dissipating members
that, after impact from a foreign object and release of a portion of a blade
or full blade, may
enable one of the functions selected from the group consisting of, dissipating
kinetic energy of
portions of the blade that may be released, shredding the blade or released
portions of the blade,
and acting to alter the trajectory of the released portion of the blade. The
energy dissipating
members may be located inside the composite blade or a portion of the energy
dissipating
members may be extend outside the composite blade and may run radially from
the base or
root of the blade to the blade tip, and may be distributed along the axial
chord length of the
blade. Additionally, some embodiments may include at least one bend in the
energy dissipating
members. The energy dissipating members may include strands or optional damage
initiators
to assist in shredding the blade in desired regions and to dissipate kinetic
energy.
100451 The term "self-shredding" is understood to include, but is not
limited to, the ability
of the composite blade to cause intended damage to the composite blade itself
after the blade
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is impacted with sufficient force to release a portion of the composite blade,
including the
ability of energy dissipating members to break, rip, cut, or bulge surrounding
composite blade
structure, including for example, a reinforced polymer matrix structure,
including matrices that
are thermoset or thermoplastic and reinforcements that include, but are not
limited to, glass,
graphite, aramid, or organic fiber of any length, size, or orientation.
Shredding may occur in
series or simultaneously at the same or different thickness depths, chords, or
spans of the
composite blade and may result in the release of strips or shards of composite
blade structure.
100461 One exemplary non-limiting embodiments of the composite blade
utilizes energy
dissipating members with a strand and damage initiators, the strand and damage
initiators being
pulled through the structure of the composite blade after the composite blade
is impacted with
sufficient force to release a portion, thereby breaking the composite blade
structure. Still other
embodiments of the composite blades include release zones along the radial
span of the blade
that work in combination with the energy dissipating members to balance impact
resistance
and frangibility. Other embodiments include energy dissipating members
including strands
with slack or extra length staggered along the blade chord in a manner to
align or alter the
trajectory of a released portion to prevent impact with a trailing blade or
other structure.
100471 Referring initially to FIG. 1, a schematic side section view of a
ducted fan gas
turbine engine 10 is shown including a fan module 12 and an engine core 14,
located along an
engine axis 32. The fan module 12 includes a fan casing 16 surrounding an
array of fan airfoils
18 extending radially distal from and coupled to a rotor 20. The engine core
14 includes a
high-pressure compressor 22, a combustor 24, and a high pressure turbine 26. A
low pressure
turbine 28 drives the fan airfoils 18. Optionally, a speed reduction device 34
may be coupled
between the low pressure turbine 28 and the rotor 20 to reduce the rotational
speed of the fan
module below that of the low pressure turbine 28. The optional speed reduction
device 34 could
be an epicyclical gearbox of a star or planetary configuration, a compound
gearbox, or other
arrangement of gearing to achieve a reduction of speed between the low
pressure turbine 28
and the rotor 20.
100481 In operation, air enters through the air inlet 30 of the engine 10
and moves through
at least one stage of compression where the air pressure may be increased and
directed to the
combustor 24. The compressed air is mixed with fuel and burned providing the
hot combustion
gas which exits the combustor 24 toward the high pressure turbine 26 and low
pressure turbine
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28. At the high pressure turbine 26 and low pressure turbine 28, energy is
extracted from the
hot combustion gas causing rotation of turbine airfoils which in turn cause
rotation about engine
axis 32 of the shafts to the high pressure compressor 22 and fan airfoils 18
respectively. With
respect to the embodiments described herein, fan airfoils 18 represent the
location of composite
blade 40 within fan module 12 and ducted fan engine 10.
100491 Referring now to FIG. 2, shown is a perspective view of unducted
counter-rotating
propeller engines 110 mounted wings on 102 of an aircraft 100. Additionally,
in FIG. 3, a side
view of a counter-rotating propeller engine 110 is shown including an engine
axis 32, cowling
114, and a fan module 116 having two stages of counter-rotating propellers,
first stage 118 and
second stage 120. Each of stages 118 and 120 has a plurality of propellers 122
and 124.
Operation of engine 110 is the same as that discussed for the ducted fan
engine 10 in FIG 1,
with fan module 116 having unducted propellers 122 and 124 that are not
surrounded by a
casing structure. A turboprop engine, although not shown in FIG. 2 or FIG 3,
has only a single
stage propeller 118, again with no surrounding casing. With respect to the
embodiments
described herein, propellers 118 and 120 represent the location of composite
blade within fan
module 116 of counter-rotating propeller engine 110 and a turboprop engine
with a single stage
propeller 118. For clarity, in all three engine configurations described above
the composite
blade would rotate around respective engine axis 32.
[0050] Considering now FIG. 1, foreign objects, such as, but not limited
to. birds, that are
channeled through inlet 30 and are ingested into fan module 12, can cause
damage to fan
airfoils 18, fan casing 16, and other downstream structures in engine 10.
Similarly, for counter-
rotating propeller engine 110, as shown in FIG. 3, foreign objects can be in
the path of fan
module 116 during engine operation, causing damage to unducted propellers 122
and 124.
Damage to fan airfoils or propellers can be particular troublesome, as these
components can be
relatively large in diameter and length when compared to engine core 14
diameter and the size
of the potential foreign object that may impact the fan airfoils or
propellers, for example, a bird
or airfield debris. This large size allows for portions of the fan airfoils or
propellers to release
and cause secondary impacts and resulting follow-on damage. This damage can
cause reduction
in engine performance and in some instances loss of engine power.
100511 FIGS. 4, 5, 6, and 7 describe time phased images of events inside
fan module 12
that may unfold after a fan airfoil 18 is impacted with a foreign object that
causes release of a
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fan airfoil 18. This front view of ducted fan engine 10 uses a conventional
stage of fan airfoils
18 and a fan casing 16. Referring now to FIGS. 4, 5, 6, and 7, each show
twenty fan airfoils
18, twenty being an exemplary number of airfoils 18 only and do not intend to
limit the
invention in any manner, and fan case 16, and represent a time sequence of
engine 10 during
release of a portion of airfoil 18. One of the airfoils 18 in each of FIGS. 4-
7 is identified with
a letter R, designating it as a release airfoil or an airfoil 18 that may be
initially impacted by a
foreign object that in turn may result in a portion of airfoil 18 to release.
Another airfoil 18,
adjacent to released airfoil R, has been identified with a letter T,
designating it as a trailing
airfoil. A trailing airfoil T is an airfoil 18 that trails or lags airfoil 18
The identification of
particular airfoils 18 as release blade and trailing blade are exemplary and
do not limit the
invention in any manner. In FIG. 4, all fan airfoils 18 are pristine, in that
they have not been
subject to impact from a foreign object. In FIG. 5, the release airfoil R has
been impacted by a
foreign object and may be now separated into two pieces. Moving to FIG. 6, the
free portion
of the release airfoil R may be about to impact the trailing airfoil T.
Finally, in FIG. 7, the
trailing airfoil T is separated into two pieces, caused by the impact of the
free portion of the
release airfoil R, with the free portion of the release airfoil R removed for
clarity.
100521 Due to the high rotational speed of the fan airfoils 18 in engine
10, any decrease in
the size of the free portion of the release airfoil decreases the kinetic
energy that the trailing
airfoil T and fan case 16 would need to withstand. This decrease in required
energy absorption
leads to a relative weight reduction in fan case 16, as it allows the removal
of containment
provisions and structure in the case 16. The weight reduction then allows for
the aircraft to
carry more fuel for longer range or increased robustness by allowing the
addition of weight in
another area of the engine 10. Another important benefit resulting from
reducing the size of the
free portion is a parallel reduction of unbalance loads that rotor 20
experiences due to the
eccentricity caused by the release of inertial load and variation of fan blade
18 loading on rotor
20 after release. These benefits can also be appreciated when considering the
open rotor engine
110 and any decrease in size of the released portions of propellers 122 and
124.
10053) As shown by the exemplary embodiments of the invention in FIG 8 and
9, this goal
may be accomplished by incorporating one or more energy dissipating members 80
into
composite blade 40. First considering FIG. 8, showing composite blade 40 in a
pristine state,
having a root 42, a tip 44, a leading edge 46, and a trailing edge 48, with
the span 52 of the
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blade 40 radially distally from root 42 to tip 44 and axial chord 54 moving
aft from leading
edge 46 to trailing edge 48. An inner flowpath 50 may be defined in the span
radially distal to
root 42 along the chord 54 and represents the lowest radial portion of the
span 52 that would
be subject to a foreign object impact event. In this exemplary embodiment,
composite blade 40
has three energy dissipating members 80, having lengths of strands 82, each
optionally
beginning in root 42 and extending radially distally toward the tip 44, and
then bending back
radially and proximally toward the inner flowpath 50, fonning at least one
optional bend 86.
Athough the energy dissipating members 80 in the embodiment begin at root 43,
the members
80 may begin anywhere in composite blade 40, for example, the tip, mid-span,
or the like.
Coupled to both ends of each strand 82 may be at least one damage initiator 84
defined in a
configuration as described above. In this embodiment, the placement of
individual energy
dissipating members 80 were selected to include one end radially below the
inner flowpath 50,
with the member running through and radially above the inner flowpath 50,
however this
placement and arrangement of members 80 is not limiting. Three energy
dissipating members
80 were shown in this exemplary embodiment, but any number of members 80 could
be used.
100541 Non-limiting embodiments of the energy dissipating members may
include strands
that may be inside, may partially extend outside, and may be co-cured with the
composite blade.
Strand materials may include, but are not limited to, Zylont a registered
trademark of Toyobo
Corporation (Poly (p-phenylene-2, 6-benzobisoxazole)) fiber, high strength
metal wires, or any
other suitable high strength material in the form of strands. Exemplary, non-
limiting
embodiments of the section shape of strands may be circular, oval, polygonal,
or irregular and
can range in sectional dimension from about 0.005 inches to about 0.075 inches
and from about
0.010 inches to about 0.030 inches. Other exemplary, non-limiting embodiments
of the
sectional area of strands can range in sectional area from about 0.0001 square
inches to about
0.02 square inches and from about 0.001 square inches to about 0.002 square
inches. Other
exemplary non-limiting strand forms may include braid, weave, strip or tape
forms. Strand
sections may be constant along the length or vary in section size, section
shape, form, and
material, including, but not limited to, increasing in size from one end of
the length to the other.
100551 Exemplary shape and material aspects of the damage initiators may be
tailored to
the contours of the composite blade in a local regions and also material
selections may be
tailored as not to react chemically with the composite blade during co-cure,
assembly, or
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composite blade operation. Non-limiting embodiments of damage initiators may
include
contoured, solid, hollow, or serrated, wedges of metallic, ceramic, or
composite construction,
which are not illustrated for ease of understanding purposes, and may also be
inside and may
be co-cured with the composite blade. Such Damage initiator materials may
include, but are
not limited to, steel, aluminum, titanium, cobalt, chromium, and nickel metal
alloys, or any
other suitable metal alloy. Other damage initiator materials may include, but
are not limited to,
ceramic oxides, including beryllia, ceria, and zirconia,
nonoxides, including
carbide, boride, nitride, and silicide, as well as oxides and nonoxides alone
or in combination,
with or without particulate reinforcement or fiber reinforcement. Another non-
limiting
embodiment of a damage initiator includes at least a partially hollow pouch at
least partially
filled with filler. Forms of fillers may include, but are not limited to,
fluids or semi-solids.
Fluids and semi-solid materials may include, but are not limited to,
silicones, gels, caulks, or
other incompressible or nearly incompressible materials, or a combination of
these, suitable for
composite manufacturing. The pouch may contain a plunger that works in
combination with a
strand and may expand the pouch by plunging to shift the contents of the pouch
when the strand
is strained, thereby initiating the shredding in the region of the composite
blade around the
pouch. Optionally, fillers may be also small solid metallic or ceramic pieces
alone or in
combination with the fluid and semi-solid fillers described above. After the
composite blade is
impacted with sufficient force to release a portion of the blade, another
exemplary non-limiting
mode of shredding utilizes energy dissipating members with a strand and a
pouch, the strand
being pulled through the structure of the composite blade, activating and
expanding the pouch,
thereby shredding the composite blade structure.
100561 The
energy dissipating members, including the non-limiting example of the strands
and damage initiators, may be at least partially covered with release agent,
film, or coating to
assist the members in dissipating energy by facilitating the initial sliding
or movement of the
member within the composite blade. Release agents may include, but are not
limited to,
Frekote a registered trademark of Henkel Corporation, EUROCOAT, Teflon a
registered
trademark of DuPont Company (polytetrafluoroethylene), or other suitable
release agents for
manufacturing composites.
100571 Any
combination of composite blade elements, including, but not limited to energy
dissipating members, strands, and damage initiators, including all variations
in location,
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material, manufacture, shape, size, sectional properties, and length
properties of any element
may be suitable for employing for energy dissipation, shredding, and
trajectory alignment. The
present invention also relates to methods for the fabrication of a composite
blade. Additionally,
the present invention relates to assembly of a frangible or composite blade
into and for use in
a rotary machine. This method may utilize any combination of composite blade
elements as
described above.
100581 Now moving to FIG. 9, an exemplary embodiment of FIG. 8 is shown in
a separated
state, similar to that described above in FIGS. 4-7 when referring to the
release blade R and
trailing blade T after being impact by the foreign object or a free portion of
the release blade
respectively. As shown, the strands 82 may be strained or stretched when the
composite blade
may be impacted. This imparted strain into the strands draws kinetic energy
from the releasing
portion the composite blade 40 reducing the impact energy an adjacent
composite blade 40 or
fan case 16 would experience and be required to withstand. Along with the
strain imparted to
the strands 82, the releasing portion of the composite blade 40 drags the co-
cured strands 82
through the internal structure of the composite blade 40, again reducing the
kinetic energy of
the released portion and concurrently shredding both the retained and the
released portion of
the blade 40. The optional damage initiators 84 assist in the shredding of the
released portion,
and may break down the larger portion into two or more portions having lower
individual
kinetic energies.
100591 FIG. 10 is another exemplary embodiment of composite blade 40, again
having a
root 42, a tip 44, a leading edge 46, and a trailing edge 48, with the span 52
of the blade 40
radially distally from root 42 to tip 44 and axial chord 54 moving aft from
leading edge 46 to
trailing edge 48. Again, an inner flowpath 50 may be defined in the span
radially above the
root 42 along the chord 54 and represents the lowest radial portion of the
span 52 that would
be subject to a foreign object impact event. In this exemplary embodiment,
composite blade 40
has five energy dissipating members 80. Each energy dissipating member 80 has
at least one
strand 82, at least a portion of which is external to the composite blade 40.
The radially
proximal end of the strand 82 is coupled to rotor 20, then the length of
strand 82 progresses
radially distal to pass through root 42, through inner flowpath 50 into span
52, where the strand
82, at its radially distal end, may be coupled to damage initiator 84, in this
exemplary
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embodiment of damage initiator 84. Five energy dissipating members 80 were
shown in this
exemplary embodiment, but any number of members 80 could be used.
100601 An exemplary damage initiator 84 as described in the composite blade
40 of FIG.
is shown in FIG. 11. This exemplary damage initiator 84 has a pouch 90, a
plunger 92, and
may be at least partially filled with filler 94. The shape and size of pouch
90 may be adapted
to be of any appropriate size, shape, and configuration to conform to the
local contours and
size of the composite blade 40 in the region it is placed and the illustrated
configurations is for
illustration purposes only. Strand 82 may pass through pouch 90 and may be
coupled to plunger
92. At least a portion of energy dissipating members 80 may be coated by
release agent 96. In
this exemplary embodiment at least a portion of the exterior of pouch 90 and
strand 82 may be
covered with release agent 96 to promote the initiation of separation and
shredding. The
perimeter of plunger 92 may be adapted to conform to pouch 90 in a "pre-event"
position,
where the blade 40 has not yet been impacted with foreign object damage to the
extent that the
energy dissipating members 80 have been activated.
100611 FIG. 12, a section view of FIG. 10, depicts pouch 90, plunger 92,
and strand 82 in
the pre-event position. In the event that composite blade 40 may be impacted
by a foreign
object, the energy imparted on the composite blade 40 may cause the release of
a portion of the
blade 40. If this event occurs, the strand 82 and plunger 92 may be activated.
This activation
may occur when the released portion of the blade 40 separates at a location
radially proximal
to the damage initiator 84 yet radially distal from the radial proximal end of
the related strand
82 that may be coupled to rotor 20. Once impacted with force that may cause
separation of the
blade 40, the released portion of the blade 40 may move radially distal from
rotor 20. However
the end of related strand 82 that may be coupled to rotor 20 may not move with
the released
blade portion, this may cause relative motion between the end of strand 82
coupled to rotor 20
and the released portion of blade 40 that may include the radially distal end
of strand 82 that
may be coupled to damage initiator 84. This relative motion may cause the
strand 82 coupled
to damage initiator 84 to be pulled substantially proximally radially into an
"after-event"
position, shown in the section view FIG. 13 of FIG. 10.
100621 As plunger 92 is pulled into the after-event position, plunger 92
may compress any
filler 94 in pouch 90. Since the perimeter of plunger 92 may conform to pouch
90, and the
pouch may be filled with an incompressible filler 94, the force imparted by
plunger 92 on filler
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94 is transferred into pouch 90, thereby expanding pouch 90. As the pouch 90
may be contained
within composite blade 40, this expansion bulges the composite blade 40 as
well. Also, with
the optional assistance of release agent 96, a separation zone may form in the
composite blade
adjacent to damage initiator 84. The expanded and separated regions of
composite blade 40
may thereby shred and weaken blade 40. The shredding may take the fortn of
delamination in
the composite structure, broken fibers, broken matrix, and the like. This
reduces the amount
of load bearing composite structure and thereby the strength of the composite
at and around the
shredded location. Since, during operation, the composite blade is under high
centrifugal loads,
this reduction in strength may lead to further damage to the composite blade
40 by distribution
of the loads over a smaller section of the blade 40. This may ultimately lead
to separation and
release of an additional portion of the blade 40.
100631 This weakening, or shredding, of composite blade 40 is repeated for
each energy
dissipating member 80 in composite blade 40 that may be activated. By
staggering the axial
and radial location of energy dissipating members 80 in composite blade 40,
sequencing and
combinations of shredding may result. This may be accomplished by placing
energy absorbing
members at varied thicknesses in the composite blade sections and by varying
the size and
shape of the damage initiators 84 to accommodate local geometry differences at
these
thicknesses and locations. Also, within an energy dissipating member 80, one
or more damage
initiators 84 may be used and may be distributed along strand 82 in a series.
Additionally,
within an energy dissipating member 80, strand 82 may have slack or extra
length between
damage initiators 84 distributed in series, the slack may shred the composite
blade 40 when the
strand 82 is dragged through composite blade 40 and may delay activation of a
damage initiator
84 that may be place in series. Five energy dissipating members 80 were shown
in this
exemplary embodiment, but any number of members 80 could be used.
100641 Referring now to FIG. 14, a sectional side view of another exemplary
embodiment
of a composite blade 40, again having a root 42, a tip 44, a leading edge 46,
and a trailing edge
48, with the span 52 of the blade 40 radially distally from root 42 to tip 44
and axial chord 54
moving aft from leading edge 46 to trailing edge 48. Again, an inner flowpath
50 may be
defined in the span radially above the root 42 along the chord 54 and
represents the lowest
radial portion of the span 52 that would be subject to a foreign object impact
event.
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100651 In the exemplary embodiment of FIG. 14, the span 52 of composite
blade 40 may
be radially apportioned into three release zones, a low span zone 60, a mid
span zone 62, and
a high span zone 64. Within each release zone there may be one or more
cavities, identified for
exemplary purposes only in the size, shape, configuration, and positioning as
illustrated, as
60A, 60B, 60C for low span zone 60, as 62A and 62B for mid Dane 62, and as 64A
and 64B
for high span zone 64. These cavities may be devoid of filler or optionally
filled with resin,
foam, loose media, or the like. The radially proximal ribs of cavities 60C,
62B, and 64B include
one or more flanges 66 paired with passages 68 connecting adjacent cavities.
Similarly, cavities
62A and MA include passages 68 connecting adjacent cavities. Three energy
dissipating
members 80 may be inside and co-cured with the composite blade 40 and run
radially from the
root 42 to the tip 44, through passages 68 and flanges 66 and may be
distributed axially along
chord 54 as not to overlap. Optional damage initiators may be coupled to the
strands at and
nest inside flanges 66.
[00661 The release zone cavities work in combination with the energy
dissipating members
and damage initiators seeking to balance the impact resistance and
frangibility of the blade
along the radial span of the blade. When a foreign object impacts the
composite blade 40 at
the high span zone 64 in the area of cavity MA with enough energy to separate
the entire high
span zone 64 portion of the composite blade 40, the energy dissipating member
80 passing
through flange 66 and passage 68 of cavity 64B will be strained, as described
in FIG. 9,
reducing the kinetic energy of the released portion. The damage initiator
nested inside flange
66 will also be pulled through flange 66 and the passage 68 and shred the
released portion, into
more than one fragment or portion, each with a lower individual kinetic
energy. However, for
the present example, the other two energy dissipating members 80 may not be
strained, as they
may be radially proximal to the released (entire high span zone 64) portion of
the composite
blade 40, and therefore have not degraded the integrity of low span zone 60
and mid span zone
63 to impact. The radially apportionment of release zone cavities combined
with multiple
energy dissipating members provides frangibility in areas radially distal to
the impact zone but
keeps impact resistance in areas proximal to the impact zone. Three energy
dissipating
members 80 were shown in this exemplary embodiment, but any number of members
80 could
be used. Similarly, three span zones and seven cavities were shown, but any
number of zones,
cavities, flanges and passages could be used.
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100671 Turning now to FIG. 15, a side view of another exemplary embodiment
of a
composite blade 40, again has a root 42, a tip 44, a leading edge 46, and a
trailing edge 48, with
the span 52 of the blade 40 radially distally from root 42 to tip 44 and axial
chord 54 moving
aft from leading edge 46 to trailing edge 48. Again, an inner flowpath 50 may
be defined in the
span radially above the root 42 along the chord 54 and represents the lowest
radial portion of
the span 52 that would be subject to a foreign object impact event. Composite
blade 40 has a
single energy dissipating member 80, running radially from the root 42 to the
tip 44 in a
staggered pattern from leading edge 46 to trailing edge 48 as not to overlap.
Other exemplary
stagger patterns for energy dissipating member 80 may start at the rotor 20 or
blade root 42,
running radially distal along span 52, in a serpentine path through chord 54
to the blade tip 44
and vary in depth through the blade 40 thickness. An additional exemplary
stagger pattern for
energy dissipating member 80 may be irregular in stagger along the span and
chord of blade
40 and may form at least one optional bend 86 as energy dissipating member 80
may run
radially distal from root 42 or rotor 20 to tip 44. This exemplary energy
dissipating member 80
may be inside and co-cured with the composite blade 40. The embodiment of the
energy
dissipating member 80 may be a strand as described in the exemplary embodiment
in FIG. 8
above. In this present embodiment, the staggered pattern may provide slack or
extra length to
member 80, as opposed to a shorter length that would run from the root 42
directly to the tip
44. Upon impact of foreign object damage to composite blade 40, the portion of
the blade 40
that may be released will pull the member 80 radially and proximally from the
released portion
reducing the kinetic energy of the released portion. Additionally, as will be
described below,
the placement and stagger of the energy dissipating member 80 can alter the
trajectory of the
released portion of composite blade 40. A single energy dissipating member 80
was shown in
this exemplary embodiment, but any number of members 80 could be used.
100681 Referring briefly back to aircraft 100, in FIG. 2, which has a
counter-rotating
propeller gas turbine engine 110, also called an open-rotor, mounted on
aircraft 100, if a portion
of a propeller is released from fan module 116, there may be a possibility
that the portion of
propeller may impact the aircraft fuselage. As briefly mentioned above, the
placement of and
stagger of an energy dissipating member within composite blade 40 will modify
the trajectory
of the released portion of composite blade 40. This modification may be
beneficial because it
may be desirable to direct the released portion away from an adjacent
composite blade 40 or
aircraft structure, potentially including an aircraft fuselage.
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100691 FIGS. 16 through 19 and FIGS. 20 through 23 describe this trajectory
modification.
The figures use a baseline blade time sequence (FIGS. 16-19) and a separate
time sequence
describing an exemplary embodiment of composite blade 40 having a modified
trajectory
(FIGS. 20-23). Like the time sequence detailed in FIGS 4-7, one of the
airfoils in each of FIGS.
16-19 is identified with a letter R, designating it as a release airfoil and
another has been
identified with a letter T, designating it as a trailing airfoil. The sequence
starts with FIG. 16
depicting a release airfoil just after impact from a foreign object and a
trailing airfoil in a
pristine condition. Next, in FIG. 17, a portion of the release airfoil may be
moving toward the
trailing airfoil, with the radial proximal end of the portion rotating toward
the trailing airfoil
but not yet impacting the trailing airfoil. Then in FIG. 18, radially proximal
end of the released
portion, although any other portion of the release airfoil can impact the
trailing airfoil, may
impact the trailing airfoil, distorting the shape of the trailing airfoil.
Finally, in FIG. 19, the
released portion of release airfoil continues to impact and further distorts
the trailing airfoil.
Depending on the kinetic energy of the released portion of the release airfoil
and the contact
location on the trailing airfoil, this level of distortion may cause the
trailing airfoil to break as
well.
100701 In contrast, as shown in FIGS. 20-23, where the exemplary embodiment
of
composite blade 40 from FIG. 15 is in the position both of the release blade,
again designated
as R, and the adjacent trailing blade, similarly designated as T, this time
sequence is repeated.
The sequence starts with FIG. 20, again depicting a release blade just after
impact from a
foreign object and a trailing blade in pristine condition. However, in FIG.
20, the released
portion of the release blade is tethered to the held portion of the released
blade by energy
dissipating member 80. Next, in FIG. 21, the released portion of the release
blade is moving
toward the trailing blade as the radial proximal end of the portion is
tethered to the held portion
by energy dissipating member 80. In FIG. 21, the energy dissipating member 80,
as described
above, has a staggered pattern providing slack or extra length in composite
blade 40. As the
kinetic energy of released portion moves the portion radially distal from the
held portion, the
slack in the energy dissipating member 80 may be pulled through the released
portion in a
preferred direction relative to the trajectory of the released portion aligned
while reducing the
kinetic energy of the released portion. As the released portion continues to
move radially distal,
the slack in the energy dissipating member 80 may be reduced with the released
portion staying
aligned with the held portion, as shown in FIG. 22. Finally, as shown in FIG.
23, when the
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slack in the energy dissipating member 80 is consumed, the member 80 may
break, with the
released portion continuing on the aligned path, both reducing the kinetic
energy of the released
portion and avoiding the trailing blade. This same concept can be used to
tether the released
portion in a manner to preferentially align the released portion predominately
aft, away from
an aircraft 100 and nearby aircraft structures.
[0071I The aforementioned exemplary embodiments of composite blade 40 can
be utilized
in rotary machines, including, but not limited to, ducted fan, open-rotor,
turbo prop gas turbine
engines, and land based gas turbines, with ranges of blade 40 counts
including, but not limited
to, from about 2 to about 24, and from about 8 to about 16, additionally from
about 10 to about
14. Span 52 of these exemplary embodiments of composite blade 40 can range
from including,
but not limited to, about 20 inches to about 90 inches, and from about 40
inches to about 70
inches, and from about 50 to about 70 inches. Chord 54 of these exemplary
embodiments of
composite blades 40 can range from including, but not limited to, about 5
inches to about 40
inches, and from about 10 inches to about 30 inches, and from about 12 to
about 24 inches.
100721 FIG. 24 shows one exemplary non-limiting process 500 for the
fabrication of a
frangible laminate, one non-limiting example frangible laminate may be a
composite blade 40.
This process 500 may include a substantially unidirectional pre-impregnated
(prepreg) process
that constructs a reinforced polymer matrix from resin and reinforcement
material 502. The
reinforcement material may take the fonn of fibers, rovings, mats, woven
rovings, woven yams,
braids, or stitched fabrics. The resin is provided as either liquid at room
temperature or may be
heated to a liquid state. Then the reinforcement material is impregnated with
the resin to form
a reinforced polymer matrix. Impregnation, also referred to as sizing, may
occur by spraying,
dipping, pasting, or similarly depositing resin on the reinforcement material
in one or more
layers or sizing steps. A non-limiting example is carbon fibers as a
unidirectional reinforcement
material that is impregnated with an epoxy resin. Other exemplary, non-
limiting, resins include
polyether ether ketone (PEEK), polyetherketoneketone (PEKK), polyphenylene
sulfide (PPS),
polyamideimide (PAT), and polyetherimides (PEI), as well as polyester,
phenolic, vinyl ester,
polyurethane, silicone, polyamide, polyamide-imide, and the like. Some of
these resins may be
toughened by incorporating discrete elastic, for example, elastomeric rubber,
or thermoplastic
material dispersed in the resin, or the like.
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100731 In the exemplay non-limiting process 500, a lay-up process may be
performed next.
The lay-up process includes cutting the reinforced polymer matrix into a
plurality of laminae
504. As used in this description, the term laminae refer to complete plies,
ply segments, and
portions of plies in shapes and strips. The laminae and a least one energy
dissipating member
80 are then stacked to produce a laminate 506. One or more energy dissipating
members 80
may be placed at varied positions in the laminate, and may be inside the
laminate or partially
outside the laminate, as shown in the exemplary embodiment of the composite
blade in FIG.
10. The process may also include ultrasonically-assisted stitching processes,
in which
reinforcement fibers may be inserted through multiple ply layers, improving
the qualities of
the laminate as a whole. The lay-up process may also include shaping the
laminae prior to and
during the stacking of laminae and energy dissipating members 80. A machine
lay-up process
may save labor cost when considered in contrast to conventional lay-up
processes that use
manual skill and labor to cut the plies and construct and shape the laminae.
100741 Finally, the process may use a consolidating process to shape and
cure the laminate
to yield a composite blade 508. A consolidating process uses consolidating
forces to press the
laminate and its laminae into the desired shape and may be part of the lay-up
process and may
be performed in-situ. One non-limiting example is an autoclave process that
places a laminate
in a high-pressure device to shape and cure the laminate. Suitable autoclave
temperatures
include temperatures from about 400 F to about 840 F, preferably from about
600 F to about
760 F.
100751 This written description uses examples to disclose the invention,
including the
preferred embodiments, and also to enable any person skilled in the art to
practice the invention,
including making and using any devices or systems and performing any
incorporated methods.
The patentable scope of the invention is defmed by the claims, and may include
other examples
that occur to those skilled in the art. Such other examples are intended to be
within the scope
of the claims if they have structural elements that do not differ from the
literal language of the
claims, or if they include equivalent structural elements with insubstantial
differences from the
literal languages of the claims. Aspects from the various embodiments
described, as well as
other known equivalents for each such aspects, can be mixed and matched by one
of ordinary
skill in the art to construct additional embodiments and techniques in
accordance with
principles of this application.
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