Dual layer sole system with auxetic structure

1. A sole system with an article of footwear, comprising: an upper; the sole system comprising a first auxetic layer and a second auxetic layer; wherein the first auxetic layer includes a plurality of apertures extending through a thickness of the first auxetic layer and arranged to form a first auxetic structure; wherein the second auxetic layer includes a plurality of projections arranged to form a second auxetic structure; wherein the first auxetic layer is disposed on a top surface of the second auxetic layer; wherein the plurality of apertures of the first auxetic layer is configured to receive the plurality of projections of the second auxetic layer such that at least a portion of each of the plurality of projections is spaced apart from a wall of a surrounding aperture from the plurality of apertures; and wherein the spacing between each projection and the surrounding aperture allows the respective projection and surrounding aperture to expand or contract independently from each other in response to a tension applied through each of the first auxetic layer and the second auxetic layer.

2. The sole system according to claim 1 , wherein the first auxetic layer has a first rigidity, wherein the second auxetic layer has a second rigidity, and wherein the second rigidity is greater than the first rigidity.

3. The sole system according to claim 1 , wherein the second auxetic layer is a ground-contacting outsole of the article of footwear.

4. The sole system according to claim 1 , wherein the first auxetic layer is disposed nearer to the upper relative to the second auxetic layer.

5. The sole system according to claim 1 , wherein the plurality of apertures are blind-hole apertures.

6. The sole system according to claim 1 , wherein the plurality of apertures are through-hole apertures.

7. The sole system according to claim 1 , wherein the second auxetic layer includes a cavity configured to receive the first auxetic layer.

8. The sole system according to claim 7 , wherein the first auxetic layer includes a first tapered sidewall and a second tapered sidewall, wherein the cavity includes a third tapered sidewall and a fourth tapered sidewall, and wherein the first auxetic layer is secured in the cavity by contact between the first tapered sidewall and the third tapered sidewall and contact between the second tapered sidewall and the fourth tapered sidewall.

9. An article of footwear, comprising:

an upper;

a sole structure with an insole and an outsole;

wherein the insole includes a bottom surface, wherein the bottom surface of the insole includes a plurality of apertures arranged to form a first auxetic structure;

wherein the outsole includes a top surface, wherein the top surface of the outsole includes a plurality of projections arranged to form a second auxetic structure;

wherein the bottom surface of the insole is disposed adjacent to the top surface of the outsole;

wherein each projection of the plurality of projections is configured to extend upward and into a corresponding aperture of the plurality of apertures when the bottom surface of the insole is disposed adjacent to the top surface of the outsole, and wherein each projection includes a portion that is spaced apart from a wall of the aperture within which it extends;

wherein the insole has a first insole sidewall and a second insole sidewall, wherein the first insole sidewall is tapered and wherein the second insole sidewall is tapered;

wherein the insole is configured to fit within a cavity of the outsole, wherein the cavity has a first cavity sidewall and a second cavity sidewall, wherein the first cavity sidewall is tapered and wherein the second cavity sidewall is tapered;

wherein the first cavity sidewall is in contact with the first insole sidewall when the insole is disposed in the cavity, wherein the second cavity sidewall is in contact with the second insole sidewall when the insole is disposed in the cavity; and

wherein the insole is secured within the article of footwear by the contact between the first insole sidewall and the first cavity sidewall and by the contact between the second insole sidewall and the second cavity sidewall.

10. The article of footwear according to claim 9 , wherein a first aperture of the plurality of apertures has a first polygonal cross-sectional shape taken along a plane parallel with a surface of the insole, and wherein a first projection of the plurality of projections has a second polygonal cross-sectional shape taken along the plane parallel with the surface of the outsole.

11. The article of footwear according to claim 10 , wherein the first polygonal cross-sectional shape is different than the second polygonal cross-sectional shape.

12. The article of footwear according to claim 10 , wherein the first polygonal cross-sectional shape is similar to the second polygonal cross-sectional shape.

13. The article of footwear according to claim 10 , wherein the first polygonal cross-sectional shape is a tri-star shape and wherein the second polygonal cross-sectional shape is a tri-star shape.

14. The article of footwear according to claim 9 , wherein the plurality of projections are arranged along a forefoot portion, a midfoot portion, and a heel portion of the outsole.

15. The sole system according to claim 1 , wherein a first aperture of the plurality of apertures has a first polygonal cross-sectional shape taken along a plane parallel with a surface of the first auxetic layer, and wherein a first projection of the plurality of projections has a second polygonal cross-sectional shape taken along the plane parallel with the surface of the second auxetic layer.

16. The sole system according to claim 15 , wherein the first polygonal cross-sectional shape is different than the second polygonal cross-sectional shape.

17. The sole system according to claim 15 , wherein the first polygonal cross-sectional shape has a first orientation and wherein the second polygonal cross-sectional shape has a second orientation; and,

wherein the first orientation is different than the second orientation.

18. The article of footwear according to claim 10 , wherein the first polygonal cross-sectional shape has a first orientation and wherein the second polygonal cross-sectional shape has a second orientation; and,

wherein the first orientation is different than the second orientation.