Sole structure for an article of footwear having enhanced roll acceleration
A sole structure for an article of footwear includes a transition region between two sole structure layers. The transition region includes a curved portion having a geometry defined by a portion of an ellipse. A plate which includes the curved portion can be provided between the two sole structure layers. The sole structure enhances the roll acceleration of the article of footwear during use.
1 . A sole structure comprising a plate, the plate comprising a curved portion having a geometry defined by a portion of an ellipse that is aligned in relation to the sole structure such that a major axis of the ellipse is tilted at an angle T from a support surface that supports the sole structure, wherein the angle T is from about 2 degrees to about 10 degrees, and the ellipse has an aspect ratio from about 1.1 to about 1.9;
wherein:
the plate includes a first end that corresponds with a heel end of the sole structure and a second end that corresponds with a toe end of the sole structure, and the curved portion extends at or beyond a midpoint of a lengthwise dimension of the plate and toward the second end of the plate;
a nadir of the plate is defined along the curved portion at a minor axis of the ellipse; and
the plate is situated within the sole structure such that the nadir of the plate is disposed between the first end and a metatarsal phalangeal joint (MPJ) location along the plate that corresponds with metatarsal bones of a foot of a user when the sole structure in incorporated as part of a shoe worn by the user, and the nadir is located a distance from the MPJ location that ranges from about 10 mm to about 40 mm.
2 . The sole structure of claim 1 , wherein the ellipse has an aspect ratio from about 1.3 to about 1.6.
3 . The sole structure of claim 1 , wherein the plate is formed of carbon.
4 . The sole structure of claim 1 , further comprising:
a first layer; and
a second layer;
wherein the plate is disposed between the first layer and the second layer.
5 . The sole structure of claim 4 , wherein the second layer is disposed below the first layer and has a hardness that is greater than a hardness of the first layer.
6 . The sole structure of claim 4 , wherein at least one of the first layer and the second layer comprises a supercritical (SC) foam material.
7 . The sole structure of claim 6 , wherein a cell size of the SC foam material is less than 100 micrometers.
8 . The sole structure of claim 7 , wherein the cell size of the SC foam material ranges from about 0.1 micrometer to about 10 micrometers.