U.S. patent application number 11/497994 was filed with the patent office on 2008-01-17 for fabrics having knit structures exhibiting auxetic properties and garments formed thereby.
This patent application is currently assigned to HBI Branded Apparel Enterprises, LLC.. Invention is credited to Andrew Alderson, Kim Lesley Alderson, Subhash Chander Anand, Naveen Ravirala, Michael Starbuck.
Application Number | 20080011021 11/497994 |
Document ID | / |
Family ID | 38997722 |
Filed Date | 2008-01-17 |
United States Patent
Application |
20080011021 |
Kind Code |
A1 |
Starbuck; Michael ; et
al. |
January 17, 2008 |
Fabrics having knit structures exhibiting auxetic properties and
garments formed thereby
Abstract
A fabric is provided that includes a knit structure having a
geometric shape imparting an auxetic property to the fabric due to
rotation of one or more portions of the knit structure. In some
aspects, the fabric includes a knit structure having a triangular
lattice shape that imparts an auxetic property to the fabric.
Inventors: |
Starbuck; Michael;
(Leicestershire, GB) ; Anand; Subhash Chander;
(Bolton, GB) ; Ravirala; Naveen; (Bolton, GB)
; Alderson; Kim Lesley; (Liverpool, GB) ;
Alderson; Andrew; (Liverpool, GB) |
Correspondence
Address: |
Charles N.J. Ruggiero, Esq.;Ohlandt, Greeley, Ruggiero & Perle, L.L.P.
10th Floor, One Landmark Square
Stamford
CT
06901-2682
US
|
Assignee: |
HBI Branded Apparel Enterprises,
LLC.
|
Family ID: |
38997722 |
Appl. No.: |
11/497994 |
Filed: |
August 2, 2006 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
11475336 |
Jun 27, 2006 |
|
|
|
11497994 |
|
|
|
|
Current U.S.
Class: |
66/170 |
Current CPC
Class: |
A43B 23/0205 20130101;
A43B 23/0245 20130101; A43B 1/04 20130101; D04B 21/06 20130101 |
Class at
Publication: |
66/170 |
International
Class: |
D04B 1/22 20060101
D04B001/22 |
Claims
1. A fabric comprising a knit structure having a geometric shape
imparting an auxetic property to the fabric due to rotation of one
or more portions of said knit structure.
2. The fabric as in claim 1, wherein said geometric shape imparts
said auxetic property due to deformation of said one or more
portions.
3. The fabric as in claim 1, wherein said geometric shape imparts
said auxetic property due to translation of said one or more
portions.
4. The fabric as in claim 1, wherein said geometric shape is
selected from the group consisting of a re-entrant honeycomb, a
star network, a re-entrant rhombic dodecahedron, a triangular
lattice, rotating squares, rotating triangles, rotating tetrahedra,
a chiral honeycomb, interlocked hexagons, interlocked
quadrilaterals, interlocked triangles, and any combinations
thereof.
5. The fabric as in claim 1, wherein the fabric is a weft knit
fabric or a warp knit fabric.
6. The fabric as in claim 1, wherein the fabric comprises a
seamless tube.
7. The fabric as in claim 1, wherein said knit structure comprises
yarns made of a material selected from the group consisting of
natural fibers, synthetic fibers, auxetic fibers, and any
combinations thereof.
8. The fabric as in claim 1, wherein said auxetic property
comprises a Poisson's ratio equal to zero.
9. The fabric as in claim 1, wherein said auxetic property
comprises a negative Poisson's ratio.
10. A fabric comprising a knit structure having a triangular
lattice shape that imparts an auxetic property to the fabric.
11. The fabric as in claim 10, wherein said auxetic property is
imparted due to rotation of one or more portions of said knit
structure, and/or translation of said one or more portions, and/or
deformation of said one or more portions.
12. The fabric as in claim 10, wherein said knit structure
comprises yarns made of a material selected from the group
consisting of natural fibers, synthetic fibers, auxetic fibers, and
any combinations thereof.
13. The fabric as in claim 10, wherein said auxetic property
comprises a Poisson's ratio equal to zero.
14. The fabric as in claim 10, wherein said auxetic property
comprises a negative Poisson's ratio.
15. A garment comprising a fabric having a knit structure that
imparts an auxetic property to said fabric due to rotation of one
or more portions of said knit structure.
16. The garment as in claim 15, wherein the garment comprises a
garment selected from the group consisting of a brassiere, a panty,
a camisole, a bathing suit, a pair of pantyhose, a leotard, a
retention bandage, a support device, a compression bandage, and any
combinations thereof.
17. The garment as in claim 15, wherein said knit structure imparts
said auxetic property due to deformation of said one or more
portions and/or due to translation of said one or more
portions.
18. The garment as in claim 15, wherein said knit structure has a
geometric shape selected from the group consisting of a re-entrant
honeycomb, a star network, a re-entrant rhombic dodecahedron, a
triangular lattice, rotating squares, rotating triangles, rotating
tetrahedra, a chiral honeycomb, interlocked hexagons, interlocked
quadrilaterals, interlocked triangles, and any combinations
thereof.
19. The fabric as in claim 15, wherein said auxetic property
comprises a Poisson's ratio of zero or less.
20. A garment comprising a fabric with a triangular lattice knit
structure that imparts an auxetic property to the fabric.
21. The garment as in claim 20, wherein said knit structure
comprises yarns made of a material selected from the group
consisting of natural fibers, synthetic fibers, auxetic fibers, and
any combinations thereof.
22. The garment as in claim 20, wherein the garment comprises a
garment selected from the group consisting of a brassiere, a panty,
a camisole, a bathing suit, a pair of pantyhose, a leotard, a
retention bandage, a support device, a compression bandage, and any
combinations thereof.
23. The garment as in claim 20, wherein said auxetic property is
imparted due to rotation of one or more portions of said knit
structure, and/or translation of said one or more portions, and/or
deformation of said one or more portions.
24. The fabric as in claim 20, wherein said auxetic property
comprises a Poisson's ratio of zero or less.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation-in-part of U.S.
application Ser. No. 11/475,336, filed on Jun. 27, 2006, now
pending.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present disclosure is related to knit structures for
fabrics. More particularly, the present disclosure is related to
fabrics having knit structures that exhibit auxetic properties and
garments formed thereby.
[0004] 2. Description of Related Art
[0005] Many types of apparel garments, such as but not limited to,
panties, brassieres, camisoles, bathing suits, pantyhose, leotards,
and others have been proposed. Similarly, many medical garments,
such as but not limited to, retention bandages, support devices,
and/or compression bandages have been proposed. As used herein,
such apparel and/or medical garments are hereinafter individually
and/or collectively referred to as "garments".
[0006] Such garments can often include one or more support and/or
shaping areas. Typically, the shaping and/or supporting functions
of such garments have been achieved using various combinations of
elastic members, foam members, support structures, such as
underwires, and the like.
[0007] It is known that many garments have a tendency to "creep" or
"ride-up" during use. This tendency can result in the garment, or
portions of thereof, moving from a desired position, to an
undesired position. Garments in this undesired position can be a
source of discomfort and/or can provide a less than optimal
aesthetic appearance. In the example where the garment is a shape
or support garment, the garment often provides less than optimal
support or shaping characteristics when in the undesired position.
Further, the tendency to creep to an undesired position can also
require the user to adjust the garment in order to return the
garment to its correct position. When the garment is an intimate
apparel garment, the requirement for such adjustments can be a
source of embarrassment.
[0008] Accordingly, there is a continuing need for fabric and
garments made therefrom that overcome, alleviate, and/or mitigate
one or more of the above deleterious effects of the prior art.
BRIEF SUMMARY OF THE INVENTION
[0009] It is an object of the present disclosure to provide fabrics
having knit structures that exhibit auxetic properties.
[0010] It is another object to provide an auxetic knit structure
that can be produced on a warp knitting machine.
[0011] These and other objects and advantages of the present
disclosure are provided by a fabric comprising a knit structure
having a geometric shape imparting an auxetic property to the
fabric due to rotation of one or more portions of the knit
structure.
[0012] These and other objects and advantages of the present
disclosure are also provided by a fabric comprising a knit
structure having a triangular lattice shape that imparts an auxetic
property to the fabric.
[0013] Further objects and advantages of the present disclosure are
provided by a garment comprising a fabric having a knit structure
that imparts an auxetic property to the fabric due to rotation of
one or more portions of the knit structure.
[0014] Still further objects and advantages of the present
disclosure are provided by a garment comprising a fabric with a
triangular lattice knit structure that imparts an auxetic property
to the fabric.
[0015] The above-described and other features and advantages of the
present disclosure will be appreciated and understood by those
skilled in the art from the following detailed description,
drawings, and appended claims.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
[0016] FIG. 1 illustrates materials having positive and negative
Poisson's ratios under out-of-plane bending;
[0017] FIG. 2 illustrates materials having positive and negative
Poisson's ratios under in-plane tension;
[0018] FIG. 3 illustrates a typical warp knit fabric;
[0019] FIG. 4 is a micrograph of a first embodiment of a fabric
according to the present disclosure in a relaxed or normal
state;
[0020] FIG. 5 is a close up micrograph of a portion of the fabric
of FIG. 4 having the approximate geometric knit structure of a
single repeat unit superimposed thereon;
[0021] FIG. 6A illustrates the approximate geometric structure of
the single repeat unit of FIG. 5 in the relaxed state;
[0022] FIG. 6B illustrates the approximate geometric structure of
the single repeat unit of FIG. 5 in the deformed state;
[0023] FIG. 7A illustrates a tessellating pattern of the repeat
unit of 6A;
[0024] FIG. 7B illustrates a tessellating pattern of the repeat
unit of 6B;
[0025] FIG. 8 is a graph plotting changes in width and length of
the fabric of FIG. 4; and
[0026] FIG. 9 is a graph plotting transverse strain data to
longitudinal strain data of the fabric of FIG. 4.
DETAILED DESCRIPTION OF THE INVENTION
[0027] Materials that exhibit positive Poisson's ratio properties,
which are discussed in detail with respect to FIGS. 1A and 2A, have
been determined by the present disclosure, when used in a garment,
to reduce the fit of the resultant garment.
[0028] As show in FIG. 1A, materials in `plate` form generally
adopt a saddle-shape curvature when exposed to out of plane bending
as a result of the positive Poisson's ratio. As shown in FIG. 2A,
materials having a positive Poisson's ratio, when exposed to
in-plane forces, namely when placed in tension in the y-direction,
contract in a direction transverse (e.g., the x-direction) to the
direction of the tensile load. It has been determined by the
present disclosure that fabrics exhibiting the aforementioned
properties (e.g., saddle curvature and positive Poisson's
contraction) can, when used to form a garment, reduce the fit of
the garment.
[0029] Advantageously, the present disclosure provides fabrics
having knit structures that exhibit auxetic properties. Materials
having "auxetic" properties, as used herein, are those materials
that have a zero or negative Poisson's ratio. An example of a
material have a negative Poisson's ratio is discussed in detail
with respect to FIGS. 1B and 2B.
[0030] As shown in FIG. 1B, materials having auxetic properties,
when subject to out of plane bending, undergo dome-shape curvature.
Accordingly, a relatively stiff garment having the auxetic knit
structures of the present disclosure, when exposed to out-of-plane
forces due to body movements, retains a better fit to the body as
compared to those having the positive Poisson's ratio as in FIG.
1A.
[0031] As shown in FIG. 2B, materials having a negative Poisson's
ratio, when exposed to in-plane forces, namely when placed in
tension in the y-direction, expand in a direction transverse (e.g.,
the x-direction) to the direction of the tensile load. Thus, a
garment having the auxetic knit structures of the present
disclosure, when exposed to in-plane forces due to body movements,
due to an increase in body size and/or shape, results in a
concomitant Poisson's ratio-induced increase in the x-direction
(when the Poisson's ratio is negative). Alternately, no increase or
decrease in the x-direction results when the Poisson's ratio is
zero. This expansion and/or lack of contraction retains a better
fit to the body as compared to those having the positive Poisson's
ratio as in FIG. 2A.
[0032] Thus, the present disclosure provides fabrics having a knit
structure such that, when the used in a garment, naturally adopts
to the doubly-curved human form yet also have the ability to grow
or shrink in all directions simultaneously.
[0033] Without wishing to be bound to any particular theory,
auxetic behavior is believed to arise due to the interplay between
the geometric structure of the material and one or more mechanisms
with which the geometrical structure deforms. In the classic
example of auxetic behavior illustrated in FIG. 2B, the geometric
structure is a re-entrant honeycomb and the mechanism with which
this structure deforms is rotation or hinging of the walls or ribs
of the honeycomb. The table below provides a summary of the main
structures and deformation mechanisms that are believed to give
rise to auxetic behavior contemplated for use in knit structures by
the present disclosure.
TABLE-US-00001 TABLE 1 Mechanism Geometric Structure Example
Rotation of Re-entrant honeycomb Deforming by rib hinging sub-units
Star network Deforming by rib hinging Re-entrant rhombic Deforming
by rib hinging dodecahedron Triangular lattice Deforming by rib
hinging Corner-sharing squares Rotating squares Corner-sharing
Rotating triangles triangles Ccorner-sharing Rotating tetrahedra
tetrahedra Deformation Re-entrant honeycomb Deforming by rib
flexure of sub-units Star network Deforming by rib flexure
Honeycomb Deforming by rib stretching Chiral honeycomb Deforming by
rib flexure Corner-sharing Deforming by dilation polyhedra (e.g.,
squares, triangles, tetrahedra, etc) Triangular lattice Deforming
by rib flexure and/or stretching Translation Interlocked hexagons
Deforming by sliding of hexagons of sub-units with respect to one
another Interlocked Deforming by sliding of quadrilaterals
quadrilaterals with respect to one another Interlocked triangles
Deforming by sliding of triangles with respect to one another
[0034] For purposes of clarity, exemplary embodiments of fabrics
having knit structures according to the present disclosure are
described as warp knit fabrics. However, it should be recognized
that the fabrics of the present disclosure can be any knit fabric
such as, but not limited to, weft knit fabrics.
[0035] Typical warp knit fabric, as illustrated in FIG. 3, has a
series of courses and a series of wales. Each course is a row of
loops or stitches running across the width of the knit fabric as
shown in FIG. 3A. Each wale is a column of loops or stitches
running along the length (e.g., warp direction) of the knit fabric
as shown in FIG. 3B.
[0036] Referring now to FIGS. 4 and 5, a first exemplary embodiment
of a warp knit fabric 10 having an auxetic knit structure 12
according to the present disclosure is shown. Knit structure 12
includes loops or stitches to form a triangular lattice structure
14 (only one illustrated).
[0037] As seen from Table 1 above, triangular lattice structures
are believed to exhibit auxetic properties via both the rib
rotation and deformation mechanisms. Specifically, triangular
lattice structures are believed to exhibit auxetic properties via
rib hinging, rib flexure, rib stretching, and any combinations
thereof.
[0038] For purposes of clarity, only the rib hinging mechanism of
triangular lattice structure 14 is discussed in detail below with
respect to FIGS. 6 and 7. Triangular lattice structure 14 has an
internal angle .alpha. and an external angle .beta.. Internal angle
.alpha. is the angle between a centerline 16 and a side 18, while
external angle .beta. is the angle between the centerline and an
end 20.
[0039] Under normal or relaxed conditions shown in FIGS. 6A and 7A,
external angle .beta. is between greater than about zero degrees
and less than about ninety degrees. However, upon application of
tension in a first direction 22 as shown in FIGS. 6B and 7B, the
ends 20 of triangular lattice structure 14 hinge so that external
angle .beta. increases but remains less than about 90 degrees. In
this manner, triangular lattice structure 14 deforms by hinging to
expand in a second direction 24, where the second direction is
about normal to the first direction 22.
[0040] Triangular lattice structure 14 is illustrated in FIG. 7 in
tessellated form, namely formed into a mosaic with a plurality of
the triangular lattice structures 14. Triangular lattice structure
14 in FIG. 7B having a deformed cell structure due to the
application of tension 22 has undergone expansion both along the
direction of the applied tension (e.g., first direction 22) and
transverse to the direction of the applied tension (e.g., second
direction 24) with respect to the relaxed tessellated structure in
FIG. 7A. Thus, triangular lattice structure 14 is auxetic when
deformation is due to the rotation of the ribs 18, 20 making up the
structure.
[0041] In this illustrated embodiment, triangular lattice structure
14 is oriented so that centerline 16 is approximately normal to the
warp direction.
[0042] The auxetic properties of fabric 10 were characterized using
combined mechanical testing and videoextensometry.
[0043] During testing, fabric 10 was knitted on a warp knitting
machine to include triangular lattice structure 14 and heat set.
Fabric 10 was then cut into swaths of about 15 centimeters (cm)
long by about 5 cm wide. The swaths were cut at about 45.degree. to
the warp direction.
[0044] FIG. 8 shows the width and length videoextensometry data for
the fabric of FIG. 4 when subject to tensile load application along
a direction that is at -45.degree. to the warp direction. FIG. 8
shows that, as the fabric is pulled to increase in length, it
expands (increases in width) and, therefore, possesses negative
Poisson's ratio behavior.
[0045] The width and length data were converted to transverse and
axial strains, respectively, using the definition of true strain
given by:
l = ln ( l l 0 ) ##EQU00001##
where .epsilon..sub.l is the strain, and l and l.sub.0 are the
length and original length, respectively, in the direction of
interest. The Poisson's ratio v.sub.ij which determines the change
in width (along the transverse j direction) for stretching along
the i direction is defined by:
v ij = - ( strain j strain i ) = - j i ##EQU00002##
[0046] The transverse and longitudinal strains were plotted against
each other, with the slope of the resultant graph being, by
definition, equal to -v.sub.ij, where i is the direction of loading
and j is the width direction. The resultant strains were plotted
and are shown in FIG. 9. The data in FIG. 8 contain the derived
strains for the average of all 10 transverse sections measured
during the test.
[0047] Next, linear best fit lines were applied to the data set in
FIG. 9, to result in a value of v.sub.12=-0.20. The data from the
testing supports this finding, as the data showed that fabric 10
has v.sub.12=-0.22.+-.0.03 and v.sub.21=-0.13.+-.0.02.
[0048] As seen from the example above, knit fabrics having knit
structures according to the present disclosure are provided that
display the auxetic (zero or negative Poisson's ratio)
property.
[0049] It should be recognised that fabric 10 is discussed above by
way of example where auxetic knit structure 12 is a triangular
lattice structure 14. Of course, it is contemplated by the present
disclosure for fabric 10 to have auxetic knit structure 12 with any
structure sufficient to impart the desired auxetic property. For
example, it is contemplated by the present disclosure for auxetic
knit structure 12 to have a geometric shape that is selected from
the group consisting of a re-entrant honeycomb, a star network, a
re-entrant rhombic dodecahedron, a triangular lattice, rotating
squares, rotating triangles, rotating tetrahedra, a chiral
honeycomb, interlocked hexagons, interlocked quadrilaterals,
interlocked triangles, and any combinations thereof.
[0050] It should also be recognised that fabric 10 is discussed
above by way of example where the auxetic property is believed to
be, at least in part, imparted by rib hinging. Of course, it is
contemplated by the present disclosure for fabric 10 to have
auxetic knit structure 12 having any structure sufficient to impart
the desired auxetic property by any desired mechanism. For example,
it is contemplated by the present disclosure for auxetic knit
structure 12 to exhibit auxetic properties via the rotation
mechanism, the deformation mechanism, the translation mechanism,
and any combinations thereof. Thus, auxetic knit structure 12 can
exhibit auxetic properties via rib hinging, flexure, rib
stretching, and any combinations thereof.
[0051] It is contemplated by the present disclosure for fabric 10
to have yarns made of natural fibers, synthetic fibers, or
combinations thereof. In some embodiments, it is contemplated by
the present disclosure fabric 10 to have yarns made of auxetic
fibers themselves, such as are disclosed in U.S. Pat. No.
6,878,320, the contents of which are incorporated by reference
herein. In these embodiments, fabric 10 can exhibit auxetic (zero
or negative Poisson's ratio) properties not only based on the knit
structure, but also due to the yarn itself.
[0052] Advantageously, fabrics according to the present disclosure
find use in the manufacture of garments such as, but not limited
to, a brassiere, a panty, a camisole, a bathing suit, a pair of
pantyhose, a leotard, a retention bandage, a support device, a
compression bandage, and others. Here, fabric 10 can form a portion
of the garment or can be used to form all of the garment. Fabric 10
can form all or part of various apparel garments such as: a
moldable part of the garment such as, a bra cup; a figure control
garment such as a foundation garment or corset; thermal-wear, where
a volume of air can be trapped-in by the auxetic fabric property
for insulation; and others. In addition, fabric 10 can form all or
part of various medical garments such as: retention bandages;
compression bandages; seamless shaped body garments for wounds
suffered due to burns; and others.
[0053] Advantageously, fabrics according to the present disclosure
can be knit on many commercially available circular knitting
machines, which knit the fabric into a seamless tube.
[0054] It should also be recognized that the terms "first",
"second", "third", "upper", "lower", and the like may be used
herein to modify various elements. These modifiers do not imply a
spatial, sequential, or hierarchical order to the modified elements
unless specifically stated.
[0055] While the present disclosure has been described with
reference to one or more exemplary embodiments, it will be
understood by those skilled in the art that various changes may be
made and equivalents may be substituted for elements thereof
without departing from the scope of the present disclosure. In
addition, many modifications may be made to adapt a particular
situation or material to the teachings of the disclosure without
departing from the scope thereof. Therefore, it is intended that
the present disclosure not be limited to the particular
embodiment(s) disclosed as the best mode contemplated, but that the
disclosure will include all embodiments falling within the scope of
the appended claims.
* * * * *