Fabrics having knit structures exhibiting auxetic properties and garments formed thereby
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.
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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 INVENTION1. Field of the Invention
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.
2. Description of Related Art
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”.
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.
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.
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 INVENTIONIt is an object of the present disclosure to provide fabrics having knit structures that exhibit auxetic properties.
It is another object to provide an auxetic knit structure that can be produced on a warp knitting machine.
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.
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.
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.
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.
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.
Materials that exhibit positive Poisson's ratio properties, which are discussed in detail with respect to
As show in
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
As shown in
As shown in
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.
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
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.
Typical warp knit fabric, as illustrated in
Referring now to
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.
For purposes of clarity, only the rib hinging mechanism of triangular lattice structure 14 is discussed in detail below with respect to
Under normal or relaxed conditions shown in
Triangular lattice structure 14 is illustrated in
In this illustrated embodiment, triangular lattice structure 14 is oriented so that centerline 16 is approximately normal to the warp direction.
The auxetic properties of fabric 10 were characterized using combined mechanical testing and videoextensometry.
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° to the warp direction.
The width and length data were converted to transverse and axial strains, respectively, using the definition of true strain given by:
where εl is the strain, and l and l0 are the length and original length, respectively, in the direction of interest. The Poisson's ratio vij which determines the change in width (along the transverse j direction) for stretching along the i direction is defined by:
The transverse and longitudinal strains were plotted against each other, with the slope of the resultant graph being, by definition, equal to −vij, where i is the direction of loading and j is the width direction. The resultant strains were plotted and are shown in
Next, linear best fit lines were applied to the data set in
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.
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.
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.
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.
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.
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.
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.
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.
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.
Type: Application
Filed: Aug 2, 2006
Publication Date: Jan 17, 2008
Applicant:
Inventors: Michael Starbuck (Leicestershire), Subhash Chander Anand (Bolton), Naveen Ravirala (Bolton), Kim Lesley Alderson (Liverpool), Andrew Alderson (Liverpool)
Application Number: 11/497,994