U.S. patent application number 17/268688 was filed with the patent office on 2022-04-14 for hybrid reinforcement fabric.
The applicant listed for this patent is Owens Corning Intellectual Capital, LLC. Invention is credited to Chloe Bertrand, Venkata S. Nagarajan, Samuel Solarski, Richard Veit.
Application Number | 20220112637 17/268688 |
Document ID | / |
Family ID | |
Filed Date | 2022-04-14 |
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United States Patent
Application |
20220112637 |
Kind Code |
A1 |
Bertrand; Chloe ; et
al. |
April 14, 2022 |
HYBRID REINFORCEMENT FABRIC
Abstract
A hybrid reinforcing fabric includes glass fibers and carbon
fibers. The hybrid reinforcing fabric can be readily infused at an
acceptable infusion speed, without requiring that the carbon fiber
tows used to form the hybrid reinforcement fabric be spread or
pre-impregnated with resin. Thus, the fabric provides for an
effective one-step (i.e., in the mold) infusion process during
composite part formation.
Inventors: |
Bertrand; Chloe; (La Motte
Servolex, FR) ; Veit; Richard; (Rochefort, FR)
; Solarski; Samuel; (La Madeleine, FR) ;
Nagarajan; Venkata S.; (New Albany, OH) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Owens Corning Intellectual Capital, LLC |
Toledo |
OH |
US |
|
|
Appl. No.: |
17/268688 |
Filed: |
August 16, 2019 |
PCT Filed: |
August 16, 2019 |
PCT NO: |
PCT/US19/46742 |
371 Date: |
February 16, 2021 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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62720427 |
Aug 21, 2018 |
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International
Class: |
D04B 21/16 20060101
D04B021/16 |
Claims
1. A hybrid reinforcing fabric comprising: a plurality of first
fibers oriented in a first direction; a plurality of second fibers
oriented in the first direction; a plurality of third fibers
oriented in a second direction; and a stitching yarn maintaining
the first fibers, the second fibers, and the third fibers in their
respective orientations, wherein the first fibers are glass fibers,
wherein the second fibers are carbon fibers, wherein the third
fibers are at least one of glass fibers and carbon fibers, wherein
the first direction is 0 degrees, wherein the second direction is
different from the first direction, wherein the second direction is
within the range of 0 degrees to 90 degrees, wherein the first
fibers and the second fibers constitute between 91 wt. % and 99.5
wt. % of the fabric, wherein the third fibers constitute between
0.5 wt. % and 9 wt. % of the fabric, wherein the glass fibers
constitute between 65 wt. % to 95 wt. % of the fabric, wherein the
carbon fibers constitute between 5 wt. % to 35 wt. % of the fabric,
wherein a linear mass density of the first fibers is between 1,200
Tex and 4,800 Tex, and wherein an areal weight of the second fibers
is between 80 g/m.sup.2 and 500 g/m.sup.2.
2. The hybrid reinforcing fabric of claim 1, wherein the stitching
yarn constitutes less than 3 wt. % of the fabric.
3. The hybrid reinforcing fabric of claim 1, wherein the stitching
yarn is a polyester yarn.
4. The hybrid reinforcing fabric of claim 1, wherein the stitching
yarn has a linear mass density between 60 dTex and 250 dTex.
5. The hybrid reinforcing fabric of claim 1, wherein the stitching
yarn forms a stitching pattern through the fabric, the stitching
pattern being selected from the group consisting of a tricot
stitching pattern, a symmetric double tricot stitching pattern, an
asymmetric double tricot stitching pattern, a symmetric diamant
stitching pattern, and an asymmetric diamant stitching pattern.
6-9. (canceled)
10. The hybrid reinforcing fabric of claim 1, wherein the stitching
yarn defines a stitching length between 3 mm to 6 mm.
11. The hybrid reinforcing fabric of claim 1, wherein the stitching
yarn defines a stitching length of 5 mm.
12. The hybrid reinforcing fabric of claim 1, wherein the stitching
yarn defines a stitching length of 4 mm.
13. The hybrid reinforcing fabric of claim 1, wherein the third
fibers are glass fibers, and wherein a glass composition of the
first fibers differs from a glass composition of the third
fibers.
14. The hybrid reinforcing fabric of claim 1, further comprising a
plurality of fourth fibers oriented in a third direction, wherein
the third fibers are glass fibers and the fourth fibers are glass
fibers, and wherein a glass composition of the third fibers is the
same as a glass composition of the fourth fibers.
15. The hybrid reinforcing fabric of claim 14, wherein an absolute
value of the second direction is equal to an absolute value of the
third direction.
16. The hybrid reinforcing fabric of claim 1, wherein a difference
between the first direction and the second direction is greater
than or equal to 45 degrees.
17. The hybrid reinforcing fabric of claim 1, wherein a difference
between the first direction and the second direction is greater
than or equal to 80 degrees.
18. (canceled)
19. The hybrid reinforcing fabric of claim 1, wherein the third
fibers are glass fibers, and wherein a linear mass density of the
third fibers is between 68 Tex and 300 Tex.
20. The hybrid reinforcing fabric of claim 1, wherein the second
fibers are fed from one or more carbon tows having a size in the
range of 6K to 50K.
21. (canceled)
22. The hybrid reinforcing fabric of claim 1, wherein the second
fibers constitute 7 wt. % of the fabric, and wherein an areal
weight of the fabric is 2,500 g/m.sup.2.
23. The hybrid reinforcing fabric of claim 1, wherein the second
fibers constitute 15 wt. % of the fabric, and wherein an areal
weight of the fabric is 1,300 g/m.sup.2.
24. The hybrid reinforcing fabric of claim 1, wherein the second
fibers constitute 15 wt. % of the fabric, and wherein an areal
weight of the fabric is 1,400 g/m.sup.2.
25. The hybrid reinforcing fabric of claim 1, wherein the second
fibers constitute 25 wt. % of the fabric, and wherein an areal
weight of the fabric is 1,300 g/m.sup.2.
26. The hybrid reinforcing fabric of claim 1, wherein the fabric
contains no resin pre-impregnated therein.
27-33. (canceled)
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims priority to and any benefit of U.S.
Provisional Patent Application No. 62/720,427, filed Aug. 21, 2018,
the entire content of which is incorporated herein by
reference.
FIELD
[0002] The inventive concepts relate generally to fibrous
reinforcement materials and, more particularly, to a hybrid fabric
including glass fibers and carbon fibers.
BACKGROUND
[0003] It is known to use glass fibers to reinforce structural
components, such as wind turbine blades. It is likewise known to
use carbon fibers to reinforce structural components, such as wind
turbine blades. These structural components are often formed by
hand laying a collection of the fibers (e.g., in the form of a
fabric) into a mold, filling the mold with a resin, and curing the
resin to form the part.
[0004] Glass fiber reinforcement materials exhibit good mechanical
properties, including strength, strain, and compression; are
relatively inexpensive; and are readily infused with a resin.
However, the elastic modulus of the glass fiber reinforcement
materials is low, which can present design limitations.
[0005] Carbon fiber reinforcement materials exhibit good mechanical
properties, including stiffness and tensile strength, at a low
density. However, the carbon fiber reinforcement materials are low
in strain, low in compressive strength, and relatively expensive.
Furthermore, the carbon fiber reinforcement materials can be
difficult to infuse with a resin.
[0006] It would be desirable to combine glass fibers and carbon
fibers into a hybrid reinforcement material for use in reinforcing
structural components, so as to take advantage of each fiber's
respective strengths while compensating for each fiber's respective
weaknesses. However, when fabrics are made with only carbon tows,
the very thin carbon fibers that are bundled together lead to poor
infusion speed.
[0007] Conventional carbon-containing reinforcement fabrics have
attempted to solve this problem by pre-impregnating the carbon tow
used to form the fabric. In other words, resin is applied to the
carbon fibers prior to the fabric being placed in a mold to form a
composite structure. In some instances, the carbon tow is also
spread (i.e., the individual carbon fibers separated) to accelerate
the rate of infusion of the carbon tow. Such a "prepreg" fabric can
introduce processing, storage, and handling difficulties.
[0008] In view of the above, there is an unmet need for a hybrid
reinforcement fabric including glass fibers and carbon fibers,
which can be readily infused with resin at an acceptable infusion
speed.
SUMMARY
[0009] The invention relates generally to a hybrid reinforcement
fabric that includes glass fibers and carbon fibers, a method of
producing the hybrid reinforcement fabric, and a composite part
formed from the hybrid reinforcement fabric.
[0010] In one exemplary embodiment, a hybrid reinforcing fabric is
provided. The hybrid reinforcing fabric comprises a plurality of
first fibers oriented in a first direction; a plurality of second
fibers oriented in the first direction; a plurality of third fibers
oriented in a second direction; and a stitching yarn maintaining
the first fibers, the second fibers, and the third fibers in their
respective orientations. The first fibers are glass fibers. The
second fibers are carbon fibers. The third fibers are glass fibers,
carbon fibers, or both glass and carbon fibers. The first direction
is 0 degrees. The second direction is different from the first
direction, wherein the second direction is within the range of 0
degrees to 90 degrees. The first fibers and the second fibers
constitute between 91 wt. % and 99.5 wt. % of the fabric. The third
fibers constitute between 0.5 wt. % and 9 wt. % of the fabric. In
the fabric, the glass fibers constitute between 65 wt. % to 95 wt.
% of the fabric, and the carbon fibers constitute between 5 wt. %
to 35 wt. % of the fabric.
[0011] In one exemplary embodiment, the stitching yarn constitutes
less than 3 wt. % of the fabric.
[0012] In one exemplary embodiment, the stitching yarn is a
polyester yarn.
[0013] In one exemplary embodiment, the stitching yarn has a linear
mass density within the range of 60 dTex to 250 dTex. In one
exemplary embodiment, the stitching yarn has a linear mass density
greater than 85 dTex. In one exemplary embodiment, the stitching
yarn has a linear mass density greater than 200 dTex. In one
exemplary embodiment, the stitching yarn has a linear mass density
greater than 225 dTex.
[0014] In one exemplary embodiment, the stitching yarn forms a
stitching pattern through the fabric, the stitching pattern being a
tricot stitching pattern.
[0015] In one exemplary embodiment, the stitching yarn forms a
stitching pattern through the fabric, the stitching pattern being a
symmetric double tricot stitching pattern.
[0016] In one exemplary embodiment, the stitching yarn forms a
stitching pattern through the fabric, the stitching pattern being
an asymmetric double tricot stitching pattern.
[0017] In one exemplary embodiment, the stitching yarn forms a
stitching pattern through the fabric, the stitching pattern being a
symmetric diamant stitching pattern.
[0018] In one exemplary embodiment, the stitching yarn forms a
stitching pattern through the fabric, the stitching pattern being
an asymmetric diamant stitching pattern.
[0019] In one exemplary embodiment, the stitching yarn defines a
stitching length between 3 mm to 6 mm. In one exemplary embodiment,
the stitching yarn defines a stitching length of 5 mm. In one
exemplary embodiment, the stitching yarn defines a stitching length
of 4 mm.
[0020] In one exemplary embodiment, the first fibers are glass
fibers and the third fibers are glass fibers, wherein a glass
composition of the first fibers differs from a glass composition of
the third fibers.
[0021] In one exemplary embodiment, the hybrid reinforcing fabric
further comprises a plurality of fourth fibers oriented in a third
direction, wherein the third fibers are glass fibers and the fourth
fibers are glass fibers, and wherein a glass composition of the
third fibers is the same as a glass composition of the fourth
fibers.
[0022] In one exemplary embodiment, an absolute value of the second
direction is equal to an absolute value of the third direction.
[0023] In one exemplary embodiment, a difference between the first
direction and the second direction is greater than or equal to 45
degrees.
[0024] In one exemplary embodiment, a difference between the first
direction and the second direction is greater than or equal to 80
degrees.
[0025] In one exemplary embodiment, a linear mass density of the
first fibers is between 600 Tex and 4,800 Tex.
[0026] In one exemplary embodiment, the third fibers are glass
fibers, wherein a linear mass density of the third fibers is
between 68 Tex and 300 Tex.
[0027] In one exemplary embodiment, the second fibers are fed from
one or more carbon tows having a size in the range of 6K to
50K.
[0028] In one exemplary embodiment, an areal weight of the second
fibers is between 80 g/m.sup.2 and 500 g/m.sup.2.
[0029] In one exemplary embodiment, the second fibers constitute 7
wt. % of the fabric, wherein an areal weight of the fabric is 2,500
g/m.sup.2.
[0030] In one exemplary embodiment, the second fibers constitute 15
wt. % of the fabric, wherein an areal weight of the fabric is 1,300
g/m.sup.2.
[0031] In one exemplary embodiment, the second fibers constitute 15
wt. % of the fabric, wherein an areal weight of the fabric is 1,400
g/m.sup.2.
[0032] In one exemplary embodiment, the second fibers constitute 25
wt. % of the fabric, wherein an areal weight of the fabric is 1,300
g/m.sup.2.
[0033] In general, the hybrid reinforcing fabric contains no resin,
i.e., none of the fibers forming the fabric are pre-impregnated
with a resin.
[0034] In one exemplary embodiment, a polyester resin has an
infusion rate through a thickness of the hybrid reinforcing fabric
(approximately 30 mm) of 9 minutes. In one case, where the fabric
had a carbon content of 15%, the infusion rate was 0.41 cm per
minute.
[0035] In one exemplary embodiment, an epoxy resin has an infusion
rate through a thickness of the hybrid reinforcing fabric
(approximately 30 mm) of 16 minutes. In one case, where the fabric
had a carbon content of 15%, the infusion rate was 0.23 cm per
minute.
[0036] In one exemplary embodiment, an epoxy resin has an infusion
rate through a thickness of the hybrid reinforcing fabric
(approximately 30 mm) of 8 minutes. In one case, where the fabric
had a carbon content of 7%, the infusion rate was 0.419 cm per
minute.
[0037] In one exemplary embodiment, an epoxy resin has an infusion
rate through the hybrid reinforcing fabric in the first direction
of between 0.238 cm per minute and 0.5 cm per minute.
[0038] In one exemplary embodiment, a polyester resin has an
infusion rate through the hybrid reinforcing fabric in the first
direction of 0.73 cm per minute.
[0039] In one exemplary embodiment, the fabric has an infusion rate
through the fabric in a direction perpendicular to the first
direction of 0.3 cm per minute.
[0040] In one exemplary embodiment, the fabric is infused with a
resin that is cured to form a composite article. In one exemplary
embodiment, the article is a wind turbine blade or related
component (e.g., spar cap).
[0041] Other aspects, advantages, and features of the inventive
concepts will become apparent to those skilled in the art from the
following detailed description, when read in light of the
accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0042] For a fuller understanding of the nature and advantages of
the inventive concepts, reference should be had to the following
detailed description taken in connection with the accompanying
drawings, in which:
[0043] FIGS. 1A-1D illustrate a hybrid reinforcing fabric,
according to an exemplary embodiment of the invention. FIG. 1A is a
top plan view of the hybrid reinforcing fabric. FIG. 1B is a bottom
plan view of the hybrid reinforcing fabric. FIG. 1C is a detailed
view of the circle A in FIG. 1A. FIG. 1D is a detailed view of the
circle B in FIG. 1B.
[0044] FIGS. 2A-2C illustrate stitching patterns that can be used
in the hybrid reinforcing fabric of FIG. 1. FIG. 2A shows a tricot
stitching pattern. FIG. 2B shows an asymmetric double tricot
stitching pattern. FIG. 2C shows an asymmetric diamant stitching
pattern.
[0045] FIG. 3 is a diagram illustrating a through thickness
infusion speed (TTIS) test for measuring the infusion rate of a
fabric.
[0046] FIGS. 4A-4B illustrate an in-plane infusion test (IPIT) test
for measuring the infusion rate of a fabric.
[0047] FIG. 5 is a graph illustrating the results of the IPIT test
of FIG. 4 performed on two (2) different fabrics to measure the
infusion rate (in the x-direction) of the fabrics.
[0048] FIG. 6 is a graph illustrating the results of the IPIT test
of FIG. 4 performed on two (2) different fabrics to measure the
infusion rate (in the y-direction) of the fabrics.
DETAILED DESCRIPTION
[0049] While the inventive concepts are susceptible of embodiment
in many different forms, there are shown in the drawings and will
be described herein in detail various exemplary embodiments thereof
with the understanding that the present disclosure is to be
considered as an exemplification of the principles of the inventive
concepts. Accordingly, the inventive concepts are not intended to
be limited to the specific embodiments illustrated herein.
[0050] Unless otherwise defined, the terms used herein have the
same meaning as commonly understood by one of ordinary skill in the
art encompassing the inventive concepts. The terminology used
herein is for describing exemplary embodiments of the inventive
concepts only and is not intended to be limiting of the inventive
concepts. As used in the description of the inventive concepts and
the appended claims, the singular forms "a," "an," and "the" are
intended to include the plural forms as well, unless the context
clearly indicates otherwise. Furthermore, the term "between" when
defining a range is intended to be inclusive of the specified end
points as well, unless the context clearly indicates to the
contrary.
[0051] It has been discovered that by controlling one or more
specific product variables including, but not necessarily limited
to, glass content, carbon content, glass-carbon ratio, stitching
yarn composition, stitching pattern, and stitching length, a hybrid
reinforcement fabric made up primarily of glass fibers and carbon
fibers can be produced that is an effective reinforcement for
structural components (e.g., wind turbine blades) and that exhibits
an acceptable rate of infusion.
[0052] Accordingly, the inventive concepts provide a hybrid
reinforcement fabric comprising glass fibers and carbon fibers. The
hybrid reinforcement fabric can be readily infused at an acceptable
infusion speed, without requiring that the carbon fiber tows used
to form the hybrid reinforcement fabric be spread or
pre-impregnated with resin. Thus, the inventive fabric provides for
an effective one-step (i.e., in the mold) infusion process during
composite part formation. The inventive concepts also encompass a
method of producing the hybrid reinforcing fabric. The inventive
concepts also encompass a composite part formed from the hybrid
reinforcing fabric.
[0053] In an exemplary embodiment of the invention, a hybrid
reinforcement fabric 100 is constructed from both glass reinforcing
fibers 102 and carbon reinforcing fibers 104, as shown in FIGS.
1A-1D.
[0054] Any suitable glass reinforcing fibers 102 can be used in the
hybrid reinforcement fabric 100. For example, fibers made from E
glass, H glass, S glass, an AR glass types can be used. In some
exemplary embodiments, basalt fibers can be used in place of some
or all of the glass reinforcing fibers 102. In general, the glass
reinforcing fibers 102 have a diameter within the range of 13 .mu.m
to 24 .mu.m. Typically, the glass reinforcing fibers 102 in the
hybrid reinforcement fabric 100 are glass fiber strands 102 (fed
from one or more glass rovings) made up of many individual
continuous glass filaments.
[0055] Any suitable carbon reinforcing fibers 104 can be used in
the hybrid reinforcement fabric 100. In general, the carbon
reinforcing fibers 104 have a diameter within the range of 5 .mu.m
to 11 .mu.m. Typically, the carbon reinforcing fibers 104 in the
hybrid reinforcement fabric 100 are carbon fiber strands 104 (fed
from one or more carbon tows) made up of many individual continuous
carbon filaments.
[0056] The hybrid reinforcement fabric 100 is a non-crimp fabric,
wherein the fibers 102, 104 are arranged in their respective
positions/orientations and then held together by a stitching yarn
106. In some embodiments, the stitching yarn 106 is made of
polyester. In some embodiments, the stitching yarn 106 has a linear
mass density between 60 dTex and 250 dTex.
[0057] Any stitching pattern suitable to hold the fibers 102, 104
of the fabric 100 together can be used. Various exemplary stitching
patterns 200 are shown in FIGS. 2A-2C. A tricot stitching pattern
200 in which reinforcing fibers 202 (e.g., the fibers 102, 104) are
held together by a stitching yarn 206 (e.g., the stitching yarn
106) is shown in FIG. 2A. An asymmetric double tricot stitching
pattern 200 in which the reinforcing fibers 202 (e.g., the fibers
102, 104) are held together by the stitching yarn 206 (e.g., the
stitching yarn 106) is shown in FIG. 2B. An asymmetric diamant
(diamond-like) stitching pattern 200 in which the reinforcing
fibers 202 (e.g., the fibers 102, 104) are held together by the
stitching yarn 206 (e.g., the stitching yarn 106) is shown in FIG.
2C. FIGS. 1C-1D illustrate a tricot stitching pattern used in the
fabric 100.
[0058] In general, the stitching pattern 200 is a repeating series
of stitches, with transitions between each individual stich portion
220 defining a stitching length 222 (see FIG. 2A). The stitching
length 222 is another variable that can influence the rate of
infusion of the fabric 100. Typically, the stitching length 222
will be within the range of 3 mm to 6 mm. In some exemplary
embodiments, the stitching length 222 is 4 mm. In some exemplary
embodiments, the stitching length 222 is 5 mm.
[0059] The hybrid reinforcement fabric 100 is a unidirectional
fabric, wherein between 91 wt. % to 99 wt. % of the reinforcing
fibers 102, 104 are oriented in a first direction and 0.5 wt. % to
9 wt. % of the reinforcing fibers 102, 104 are oriented in one or
more other directions (e.g., second and third directions).
[0060] Typically, the first direction will be 0.degree. (lengthwise
direction of the fabric).
[0061] The second direction is different from the first direction.
The second direction will generally be between greater than
0.degree. and less than or equal to 90.degree..
[0062] The third direction is different from the first direction.
The third direction will generally be greater than 0.degree. and
less than or equal to 90.degree..
[0063] The third direction may be the same as the second direction
(such that there are only two distinct fiber orientations in the
fabric). Otherwise, the third direction will typically be equal to
the negative orientation of the second direction.
[0064] In the hybrid reinforcement fabric 100 shown in FIGS. 1A-1D,
the first direction is 0.degree., the second direction is
80.degree., and the third direction is -80.degree..
[0065] In some exemplary embodiments, all of the reinforcing fibers
oriented in the second direction are glass reinforcing fibers
102.
[0066] In some exemplary embodiments, all of the reinforcing fibers
oriented in the third direction are glass reinforcing fibers
102.
[0067] In some exemplary embodiments, the glass reinforcing fibers
102 oriented in the first direction include a different glass
composition than the glass reinforcing fibers 102 oriented in the
second direction.
[0068] In some exemplary embodiments, the glass reinforcing fibers
102 oriented in the first direction include a different glass
composition than the glass reinforcing fibers 102 oriented in the
third direction.
[0069] In some exemplary embodiments, the glass reinforcing fibers
102 oriented in the second direction include the same glass
composition as the glass reinforcing fibers 102 oriented in the
third direction.
[0070] The hybrid reinforcement fabric 100 comprises between 65 wt.
% to 95 wt. % of glass reinforcing fibers 102 and between 5 wt. %
to 35 wt. % of carbon reinforcing fibers 104. The stitching yarn
106 comprises a maximum of 3 wt. % of the fabric 100.
[0071] The linear mass density of the glass reinforcing fibers 102
being fed in the first direction is between 1,200 Tex and 4,800
Tex. The linear mass density of the glass reinforcing fibers 102
being fed in the non-first direction (i.e., the second/third
directions) is between 68 Tex and 300 Tex.
[0072] The tow size of the carbon reinforcing fibers 104 being fed
in the first direction is between 6K and 50K. The nomenclature #k
means that the carbon tow is made up of #.times.1,000 individual
carbon filaments.
[0073] The areal weight of the carbon reinforcing fibers 104 in the
fabric 100 is between 80 g/m.sup.2 to 500 g/m.sup.2. In some
exemplary embodiments, the hybrid reinforcement fabric 100 has
approximately 7 wt. % of carbon reinforcing fibers 104, with the
fabric 100 having an areal weight of approximately 2,500 g/m.sup.2.
In some exemplary embodiments, the hybrid reinforcement fabric 100
has approximately 15 wt. % of carbon reinforcing fibers 104, with
the fabric 100 having an areal weight of approximately 1,300
g/m.sup.2. In some exemplary embodiments, the hybrid reinforcement
fabric 100 has approximately 15 wt. % of carbon reinforcing fibers
104, with the fabric 100 having an areal weight of approximately
1,400 g/m.sup.2. In some exemplary embodiments, the hybrid
reinforcement fabric 100 has approximately 25 wt. % of carbon
reinforcing fibers 104, with the fabric 100 having an areal weight
of approximately 1,300 g/m.sup.2.
[0074] As known in the art, the glass reinforcing fibers 102 may
have a chemistry applied thereon during formation of the fibers
102. This surface chemistry, typically in an aqueous form, is
called a sizing. The sizing can include components such as a film
former, lubricant, coupling agent (to promote compatibility between
the glass fibers and the polymer resin), etc. that facilitate
formation of the glass fibers and/or use thereof in a matrix resin.
In some exemplary embodiments, the glass reinforcing fibers 102
include a polyester compatible sizing. In some exemplary
embodiments, the glass reinforcing fibers 102 include an epoxy
compatible sizing.
[0075] Likewise, as also known in the art, the carbon reinforcing
fibers 104 may have a chemistry applied thereon during formation of
the fibers 104. This surface chemistry, typically in an aqueous
form, is called a sizing. The sizing can include components such as
a film former, lubricant, coupling agent (to promote compatibility
between the carbon fibers and the polymer resin), etc. that
facilitate formation of the carbon fibers and/or use thereof in a
matrix resin. In some exemplary embodiments, the carbon reinforcing
fibers 104 include a polyester compatible sizing. In some exemplary
embodiments, the carbon reinforcing fibers 104 include an epoxy
compatible sizing.
[0076] The sizing can also include additives beyond those
conventionally associated with the fiber forming process. For
example, the sizing can include one or more additives that impart
or otherwise improve properties of the glass reinforcing fibers
102, the carbon reinforcing fibers 104, and/or the composite
materials (e.g., structural components) reinforced thereby. One
exemplary additive is graphene. In some exemplary embodiments, at
least a portion of the glass reinforcing fibers 102 and/or at least
a portion of the carbon reinforcing fibers 104 have a sizing
applied thereon, during formation of the fibers, that includes
graphene.
[0077] In some exemplary embodiments, the glass reinforcing fibers
102 and/or the carbon reinforcing fibers 104 may also have a
post-coating applied thereto. Unlike a sizing, the post-coating is
applied after formation of the fibers. As with the sizing discussed
above, the post-coating can include one or more additives that
impart or otherwise improve properties of the glass reinforcing
fibers 102, the carbon reinforcing fibers 104, and/or the composite
materials (e.g., structural components) reinforced thereby. One
exemplary additive is graphene. In some exemplary embodiments, at
least a portion of the glass reinforcing fibers 102 and/or at least
a portion of the carbon reinforcing fibers 104 have a post-coating
applied thereon, after formation of the fibers, that includes
graphene.
[0078] The hybrid reinforcing fabrics disclosed herein (e.g., the
hybrid reinforcement fabric 100) have combinations of structural
components and/or properties that improve the resin infusion rate
of the fabrics, even when the reinforcing fibers making up the
fabric are not pre-impregnated with resin. As noted above, these
components/properties include the glass content, the carbon
content, the glass-carbon ratio, the stitching yarn composition,
the stitching pattern, and the stitching length used in the hybrid
reinforcing fabrics.
[0079] One test for the measuring the resin infusion rate of a
fabric is called the through thickness infusion speed (TTIS) test.
The TTIS test will be explained with reference to FIG. 3. In the
TTIS test 300, multiple layers 302 of a fabric 304 to be tested
(e.g., the hybrid reinforcement fabric 100) are placed on an
infusion table 306. In general, many layers 302 of the fabric 304
are used for the TTIS test 300. Typically, the number of layers 302
is based on a target "testing thickness." In some exemplary
embodiments, the target thickness is 30 mm. A vacuum foil 308 is
placed over the layers 302 on top of the table 306 to form an
airtight enclosure 350 (i.e., vacuum bag).
[0080] A supply 310 of resin 312 is situated below, or otherwise in
proximity to, the table 306, such that the resin 312 can be drawn
into the enclosure 350 (e.g., through one or more openings (not
shown) in the bottom of the table 306) below the layers 302 of the
fabric 304. In some exemplary embodiments, the resin 312 is located
remote from the table 306, but is fed thereto through a supply hose
(not shown). An opening 320 in the vacuum bag formed from the foil
308 is interfaced with a hose 322 so that a vacuum source (not
shown) can be used to evacuate air from the enclosure 350 and suck
the resin 312 through the fabric 304.
[0081] In this manner, the resin 312 is pulled from the supply 310
into the enclosure 350 (see arrow 330); through the layers 302 of
the fabric 304 (see arrows 332); and out the opening 320 through
the hose 322 (see arrow 334). Given the close-fitting dimensions of
the layers 302 of the fabric 304 within the enclosure 350, the only
path for the resin 312 to travel is through the layers 302 of the
fabric 304, i.e., through the thicknesses (z-direction) of the
layers 302 of the fabric 304. The TTIS test 300 measures the amount
of time it takes until the resin 312 is first visible on an upper
surface 340 of a top layer 302 of the fabric 304. This amount of
time (e.g., in minutes) is used as a measure of the rate of
infusion of the fabric 304. The TTIS test 300 can be used to
compare the rates of infusion of different fabrics, so long as the
other testing parameters are substantially the same. Additionally,
for comparison purposes, the fabrics should have similar
grammage.
[0082] Another test for the measuring the resin infusion rate of a
fabric is called the in-plane infusion test (IPIT) test. The IPIT
test will be explained with reference to FIGS. 4A-4B. In the IPIT
test 400, five (5) layers of a fabric 404 to be tested (e.g., the
hybrid reinforcement fabric 100) are placed on an infusion table
406. A vacuum foil 408 is placed over the edges of the layers on
top of the table 406, and sealed to the table 406 (e.g., using
tape), to form an airtight enclosure 410 (i.e., vacuum bag).
[0083] All of the layers of the fabric 404 in the enclosure 410 are
aligned with one another so as to face in the same direction (e.g.,
the first orientation of each layer of the fabric 404 aligns with
the first orientation of each other layer of the fabric 404) within
the enclosure 410.
[0084] The vacuum foil 408 (and tape) form the airtight enclosure
410 except for an input opening 412 and an output opening 414
formed near opposite ends of the fabric 404.
[0085] A supply of resin 420 is situated adjacent to, or otherwise
in proximity to, the input opening 412. As configured, the resin
420 can be drawn into the enclosure 410 through the input opening
412. In some exemplary embodiments, the resin 420 is located remote
from the table 406, but is fed thereto through a supply hose (not
shown) interfaced with the input opening 412. The output opening
414, on the other side of the enclosure 410, is interfaced with a
hose (not shown) so that a vacuum source 422 can be used to
evacuate air from the enclosure 410 and suck the resin 420 through
the fabric 404.
[0086] In this manner, the resin 420 is pulled from the supply into
the enclosure 410 (see arrow 430); through the layers of the fabric
404 (see arrows 440 in FIG. 4B); and out the opening 414 through
the hose (see arrow 432). Given the close-fitting dimensions of the
layers of the fabric 404 within the enclosure 410, the only path
for the resin 420 to travel is through the layers of the fabric
404, i.e., through the length (x-direction, production direction)
or width (y-direction) of the layers of the fabric 404, depending
on the orientation of the fabric 404 between the openings 412, 414
of the enclosure 410. Thus, only the resin channels within the
layers of the fabric 404 are used to transport the resin 420.
[0087] The IPIT test 400 measures the distance covered by the resin
420 over time. A flow front (distance) of the resin 420 is recorded
after 2, 4, 6, 8, 10, 12, 16, 20, 26, 32, 38, 44, 50, 55, and 60
minutes. The current distance that the resin 420 has traveled
through the fabric 404 is referred to as the infusion length. The
measured amount of time (e.g., in minutes) relative to the infusion
length (e.g., in centimeters) is used as a measure of the rate of
infusion of the fabric 404. The IPIT test 400 can be used to
compare the rates of infusion of different fabrics, so long as the
other testing parameters are substantially the same. Additionally,
for comparison purposes, the fabrics should have similar warp
grammage.
Examples
[0088] Two (2) different fabrics were assessed using the IPIT test
400 to measure the infusion rate in both the x-direction and the
y-direction. The first fabric contained only glass reinforcing
fibers (i.e., no carbon reinforcing fibers), and served as the
reference fabric. The second fabric contained 15% carbon
reinforcing fibers (and, thus, 85% glass reinforcing fibers), and
was produced according to the general inventive concepts. The
measurements for the first fabric (UD 1200) are provided in Table
1. The measurements for the inventive hybrid fabric (15% carbon
content) are provided in Table 2.
TABLE-US-00001 TABLE 1 Time (min.) Length (Y) (cm) Length (X) (cm)
2 6.5 9.5 4 7.4 11.0 6 8.2 12.3 8 8.7 13.3 10 9.1 14.1 12 9.4 14.6
16 10.1 15.6 20 10.7 16.5 26 11.4 17.7 32 12.2 18.9 38 12.9 19.9 44
13.5 20.8 50 13.9 21.7 55 14.2 22.3 60 14.7 22.8
TABLE-US-00002 TABLE 2 Time (min.) Length (Y) (cm) Length (X) (cm)
2 8.1 11.5 4 9.0 13.8 6 9.9 15.4 8 10.7 16.9 10 11.5 18.1 12 11.9
19.1 16 12.6 20.7 20 13.1 22.1 26 14.4 23.9 32 15.2 25.8 38 16.0
27.3 44 16.8 28.8 50 17.4 30.2 55 18.0 31.4 60 18.5 32.4
[0089] FIG. 5 is a graph 500 that shows the results of the IPIT
test 400 performed on two (2) different fabrics to measure the
infusion rate (in the x-direction) of the fabrics. A first fabric
502 is made up of 100% glass reinforcing fibers (i.e., no carbon
reinforcing fibers), uses a polyester stitching yarn, uses a
stitching yarn of 110 dTex, and uses a stitching length of 5 mm. A
second fabric 504 is made up of 85% glass reinforcing fibers and
15% carbon reinforcing fibers, uses a polyester stitching yarn,
uses a stitching yarn of 220 dTex, and uses a stitching length of 4
mm. The first fabric 502 corresponds to the fabric detailed in
Table 1 above, while the second fabric 504 corresponds to the
fabric detailed in Table 2 above.
[0090] FIG. 6 is a graph 600 illustrating the results of the IPIT
test 400 performed on two (2) different fabrics to measure the
infusion rate (in the y-direction) of the fabrics. A first fabric
602 is made up of 100% glass reinforcing fibers (i.e., no carbon
reinforcing fibers), uses a polyester stitching yarn, uses a
stitching yarn of 110 dTex, and uses a stitching length of 5 mm. A
second fabric 604 is made up of 85% glass reinforcing fibers and
15% carbon reinforcing fibers, uses a polyester stitching yarn,
uses a stitching yarn of 220 dTex, and uses a stitching length of 4
mm. The first fabric 602 corresponds to the fabric detailed in
Table 1 above, while the second fabric 604 corresponds to the
fabric detailed in Table 2 above.
[0091] The hybrid reinforcing fabrics described herein (e.g., the
hybrid reinforcement fabric 100) can be combined with a resin
matrix, such as in a mold, to form a composite article. Any
suitable resin system can be used. In some exemplary embodiments,
the resin is a vinyl ester resin. In some exemplary embodiments,
the resin is a polyester resin. In some exemplary embodiments, the
resin is an epoxy resin. In some exemplary embodiments, the resin
includes a viscosity modifier.
[0092] The infusion rate of various resin systems through different
embodiments of a hybrid reinforcing fabric (e.g., differing carbon
contents) are shown in Table 3 below.
TABLE-US-00003 TABLE 3 Resin 7% Carbon 15% Carbon 25% Carbon
infusion rate epoxy 8 min 16 min 16 min through a thickness (0.419
cm/min) (0.23 cm/min) of the fabric polyester 9 min (approximately
30 mm) (0.41 cm/min) infusion rate epoxy 32 cm in 60 min 32 cm in
60 min 30 cm in 60 min through the (0.6 cm/min) (0.6 cm/min) (0.5
cm/min) fabric in the polyester 44 cm in 60 min first direction
(0.73 cm/min) infusion rate epoxy 20 cm in 60 min 18 cm in 60 min
through the fabric (0.33 cm/min) (0.3 cm/min) in the second
polyester 16 cm in 60 min direction (0.27 cm/min)
[0093] Any suitable composite forming process can be used, such as
vacuum-assisted resin transfer molding (VARTM). The composite
article is reinforced by the hybrid reinforcing fabric. In some
exemplary embodiments, the composite article is a wind turbine
blade or related component (e.g., spar cap). The hybrid reinforcing
fabrics disclosed and suggested herein may achieve improved
mechanical properties (versus a comparable glass-only fabric). For
example, a hybrid reinforcing fabric (having a 15% carbon content)
can exhibit a modulus improvement of approximately 30% and a
fatigue improvement between 40% and 50%, as compared to a similar
glass-only fabric (e.g., having the same grammage, such as 1,323
g/m.sup.2).
[0094] The above description of specific embodiments has been given
by way of example. From the disclosure given, those skilled in the
art will not only understand the inventive concepts and their
attendant advantages, but will also find apparent various changes
and modifications to the structures and concepts disclosed. It is
sought, therefore, to cover all such changes and modifications as
fall within the spirit and scope of the general inventive concepts,
as defined herein and by the appended claims, and equivalents
thereof.
* * * * *