Footwear insert formed from a composite assembly having anti-puncture and anisotropic properties
A footwear assembly having an upper configured to receive a foot and a sole assembly integrally connected to the upper. The sole assembly includes an outsole and a midsole coupled between the upper and the outsole. The sole assembly also includes a footwear insert coupled to the midsole having anisotropic and anti-puncture properties so as to provide protection, support, and stability to the foot of a wearer of the footwear assembly while still allowing for flexibility. The footwear insert is formed from a soft, dorsal layer having woven fabric, a hard, plantar layer formed from a fiber reinforced composite material bonded to the dorsal layer, and an interfacing polymer layer interposed between the dorsal and plantar layers and used to bond the two layers together. The layered arrangement has a high resistance to bending in a first direction and a low resistance to bending in an opposing second direction.
1. An anti-puncture footwear insert configured to be incorporated into a sole assembly for an article of footwear and having anisotropic bending properties, the footwear insert comprising:
a first layer comprising fabric having a compressive modulus and a tensile modulus greater than the compressive modulus;
a second layer comprising a fiber reinforced material positioned under the fabric;
an interfacing polymer layer interposed between the first layer and the second layer; and
a neutral bending plane disposed in the first layer;
wherein
the interfacing polymer layer comprises a polymer configured to act as an adhesive to bond the first layer to the second layer,
the footwear insert has a high resistance to bending in a first longitudinal direction and a low resistance to bending in an opposing second longitudinal direction, and
the first layer is configured to be in tension when the footwear insert bends in the first longitudinal direction and in compression when the footwear insert bends in the second longitudinal direction.
2. The footwear insert of claim 1 wherein the fabric comprises a plurality of sheets of woven material stitched together.
3. The footwear insert of claim 2 wherein the woven material comprises a material selected from the group consisting of polyester, Kevlar, and Dyneema.
4. The footwear insert of claim 1 wherein the fiber reinforced material comprises a fiber material impregnated with an epoxy.
5. The footwear insert of claim 4 wherein the first layer, the second layer, and the interfacing polymer layer are co-cured together such that the fabric is at least partially impregnated with the polymer of the interfacing polymer layer and the epoxy.
6. The footwear insert of claim 4 wherein the fiber material comprises fiberglass.
7. The footwear insert of claim 1 wherein the first longitudinal direction is a dorsal flex direction and the second longitudinal direction is a plantar flex direction.
8. A footwear assembly, comprising:
an upper configured to receive a foot; and
a sole assembly coupled to the upper, wherein the sole assembly comprises:
an outsole;
a midsole coupled to the outsole; and
a footwear insert coupled to the midsole, the footwear insert having anisotropic bending and anti-puncture properties, wherein the footwear insert comprises:
a dorsal layer comprising fabric;
a plantar layer comprising a fiber reinforced material positioned under the dorsal layer;
an interfacing polymer layer interposed between the plantar layer and the dorsal layer and configured to bond the dorsal layer to the plantar layer; and
a neutral bending plane disposed in the dorsal layer;
wherein the sole assembly has a high resistance to bending in a first longitudinal direction and a low resistance to bending in an opposing second longitudinal direction.
9. The footwear assembly of claim 8 wherein the fiber reinforced material comprises a fiberglass weave embedded within an epoxy.
10. The footwear assembly of claim 9 wherein the fabric comprises a plurality of sheets of woven polyester fabric stitched together.
11. The footwear assembly of claim 10 wherein the woven polyester fabric has a compressive modulus and a tensile modulus greater than the compressive modulus, wherein the woven polyester fabric is in tension when the sole assembly bends in the first direction and compression when the sole assembly bends in the second direction.
12. The footwear assembly of claim 11 wherein the first longitudinal direction is a dorsal flex direction and the second longitudinal direction is a plantar flex direction.
13. The footwear assembly of claim 8 wherein the interfacing polymer layer comprises a polymer and wherein the fabric of the dorsal layer is at least partially impregnated with the polymer.
14. The footwear assembly of claim 13 wherein the fiber reinforced material comprises a fiberglass weave impregnated with an epoxy and wherein the fabric of the dorsal layer is at least partially impregnated with the polymer and the epoxy.
15. The footwear assembly of claim 8 wherein the midsole comprises a polymer-based layer and wherein the footwear insert is completely embedded within the polymer-based layer.