SOLE STRUCTURE FOR ARTICLE OF FOOTWEAR

Description

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims priority under 35 U.S.C. § 119(e) to U.S. Provisional Application No. 63/709,662, filed on Oct. 21, 2024. The disclosure of this prior application is considered part of the disclosure of this application and is hereby incorporated by reference in its entirety.

FIELD

The present disclosure relates generally to an article of footwear and, more particularly, to a sole structure for an article of footwear.

BACKGROUND

This section provides background information related to the present disclosure, which is not necessarily prior art.

Articles of footwear conventionally include an upper and a sole structure. The upper may be formed from any suitable material(s) to receive, secure, and support a foot on the sole structure. The upper may cooperate with laces, straps, or other fasteners to adjust the fit of the upper around the foot. A bottom portion of the upper, proximate to a bottom surface of the foot, attaches to the sole structure.

Sole structures generally include a layered arrangement extending between a ground surface and the upper. For example, a sole structure may include a midsole and an outsole. The midsole is generally disposed between the outsole and the upper and provides cushioning for the foot. The midsole may include various cushioning and support structures that compress resiliently under an applied load to cushion the foot by attenuating ground-reaction forces. Examples of known cushioning structures include resilient materials, such as foams, and fluid-filled structures, such as airbags or bladders. The outsole provides abrasion-resistance and traction with the ground surface and may be formed from rubber or other materials that impart durability and wear-resistance, as well as enhance traction with the ground surface.

While sole structures have proven acceptable for their intended purposes, a continuous need for improvement in the relevant art remains. A need also exists for an article of footwear having improved overall comfort and fit while providing such improved performance.

Additionally, there is a growing demand for sole structures that offer enhanced energy return, which can improve athletic performance by reducing fatigue and increasing output. Furthermore, advancements in materials science present opportunities to develop lighter, more flexible sole structures without compromising durability or support. Cost efficiency is also a critical factor, as there is a need to produce high-performance sole structures at a lower cost.

DRAWINGS

The drawings described herein are for illustrative purposes only of selected configurations and are not intended to limit the scope of the present disclosure.

FIG. 1 is a lateral side view of a sole structure for an article of footwear according to an example of the present disclosure;

FIG. 2 is a medial side view of the sole structure of FIG. 1;

FIG. 3 is an exploded top perspective view of the sole structure of FIG. 1;

FIG. 4 is a bottom plan view of the sole structure of FIG. 1;

FIG. 5 is a lateral side view of another sole structure for an article of footwear according to an example of the present disclosure;

FIG. 6 is an enlarged, fragmentary, bottom perspective view of the sole structure of FIG. 5;

FIG. 7 is a lateral side view of another sole structure for an article of footwear according to an example of the present disclosure;

FIG. 8 is a cross-section view of a support structure of the sole structure of FIG. 7, taken through a central plane of the support structure;

FIG. 9 is a lateral side view of another sole structure for an article of footwear according to an example of the present disclosure;

FIG. 10 shows a graph illustrating the measured relationship between load and displacement for each of (i) an air-filled bladder (ii) a first foam material, and (iii) a support structure according to the principles of the present disclosure;

FIG. 11A shows example configurations of support structures according to the principles of the present disclosure;

FIG. 11B shows a graph illustrated a measured relationship between load and displacement for each of the support structures of FIG. 11A;

FIG. 12A shows a comparison of support structures having elbows incorporated into the struts according to principles of the present disclosure;

FIG. 12B shows a graph illustrated a measured relationship between load and displacement for each of the support structures of FIG. 12A;

FIG. 12C shows a graph illustrated a measured relationship between load and displacement for each of the support structures of FIG. 12C and a control support structure;

FIG. 13A shows a comparison of a first support structure having a twist incorporated into the struts and a second support structure having elbows incorporated into the struts according to principles of the present disclosure;

FIG. 13B shows a graph illustrated a measured relationship between load and displacement for each of the support structures of FIG. 13A;

FIG. 14A shows an example truss structure for a sole structure according to the principles of the present disclosure, where the truss structure is in a natural state;

FIG. 14B shows the truss structure of FIG. 14A in a first loaded state;

FIG. 14C shows the truss structure of FIG. 14B in a second loaded state;

FIG. 14D shows a graph illustrating the measured relationship between load and displacement for each of (i) a truss structure according to the principles of the present disclosure, (ii) a first foam material, and (iii) a second foam material;

FIG. 14E shows a graph showing the measured relationship between absorbed energy and displacement for each of (i) a truss structure according to the principles of the present disclosure, (ii) a first foam material, and (iii) a second foam material;

FIGS. 15A-15C show examples of truss structures having different strut angles according to the principles of the present disclosure;

FIG. 15D shows a graph illustrating the measured effect of strut angle on the relationship between displacement and load for the example truss structures of FIGS. 15A-15C;

FIGS. 16A-16C show examples of truss structures having different strut thicknesses according to the principles of the present disclosure;

FIG. 16D shows a graph illustrating the measured effect of strut thickness on the relationship between displacement and load for the example truss structures of FIGS. 16A-16C;

FIGS. 17A-17D show examples of truss structures having different twist angles according to the principles of the present disclosure;

FIG. 17E shows a graph illustrating the measured effect of twist angle on the relationship between displacement and load for the example truss structures of FIGS. 17A-17D; and

FIGS. 18A and 18B show example cross sections of struts for truss structures according to the principles of the present disclosure.

Corresponding reference numerals indicate corresponding parts throughout the drawings.

DETAILED DESCRIPTION

Example configurations will now be described more fully with reference to the accompanying drawings. Example configurations are provided so that this disclosure will be thorough, and will fully convey the scope of the disclosure to those of ordinary skill in the art. Specific details are set forth such as examples of specific components, devices, and methods, to provide a thorough understanding of configurations of the present disclosure. It will be apparent to those of ordinary skill in the art that specific details need not be employed, that example configurations may be embodied in many different forms, and that the specific details and the example configurations should not be construed to limit the scope of the disclosure.

The terminology used herein is for the purpose of describing particular exemplary configurations only and is not intended to be limiting. As used herein, the singular articles “a,” “an,” and “the” may be intended to include the plural forms as well, unless the context clearly indicates otherwise. The terms “comprises,” “comprising,” “including,” and “having,” are inclusive and therefore specify the presence of features, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, steps, operations, elements, components, and/or groups thereof. The method steps, processes, and operations described herein are not to be construed as necessarily requiring their performance in the particular order discussed or illustrated, unless specifically identified as an order of performance. Additional or alternative steps may be employed.

When an element or layer is referred to as being “on,” “engaged to,” “connected to,” “attached to,” or “coupled to” another element or layer, it may be directly on, engaged, connected, attached, or coupled to the other element or layer, or intervening elements or layers may be present. In contrast, when an element is referred to as being “directly on,” “directly engaged to,” “directly connected to,” “directly attached to,” or “directly coupled to” another element or layer, there may be no intervening elements or layers present. Other words used to describe the relationship between elements should be interpreted in a like fashion (e.g., “between” versus “directly between,” “adjacent” versus “directly adjacent,” etc.). As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items.

The terms first, second, third, etc. may be used herein to describe various elements, components, regions, layers and/or sections. These elements, components, regions, layers and/or sections should not be limited by these terms. These terms may be only used to distinguish one element, component, region, layer or section from another region, layer or section. Terms such as “first,” “second,” and other numerical terms do not imply a sequence or order unless clearly indicated by the context. Thus, a first element, component, region, layer or section discussed below could be termed a second element, component, region, layer or section without departing from the teachings of the example configurations.

Conventional cushioning elements for articles of footwear often rely on material properties of one or more compressible materials, such as fluids and polymers. For instance, known sole structures may include solid bodies of compressible foam materials to provide cushioning characteristics along the sole structure. Other examples may rely on compressible fluids, such as air or nitrogen, to provide cushioning characteristics. While suitable, the use of conventional compressible structures (e.g., foam, bladders) results in a direct relationship between displacement (e.g., compression) of the compressible material and load applied to the compressible material. In other words, increased displacement results in increased load. Furthermore, the stiffness of these materials also increases with displacement, causing the increases in load to become larger and larger. This relationship results in an underfoot feel in which increased loads associated with actions such as running or jumping (as opposed to lower loads associated with walking) may result in a stiffer underfoot feel as the cushioning material (e.g., air, foam) is compressed to a greater extent.

In the present disclosure, designs for cushioning structures have been identified that provide an improved underfoot feel during a gait cycle. The cushioning structures include various examples of truss structures each having a plurality of struts configured to extend between an upper support surface of a sole structure and a ground-engaging surface. When a load is applied to the upper support surface of the sole structure, the load is transferred along a longitudinal axis of each of the struts. The struts may be oriented at oblique angles relative to the support surface and the applied load such that a load applied as a purely compressive load to the support surface is converted into a compressive load and a bending load distributed along the strut. As the applied load increases, the resulting bending load applied to each strut causes the strut to bend or flex resiliently along its length. Increased bending along each strut induces a corresponding reduction in the compressive force required to displace or deflect the strut. In other words, as the strut bends more, the strut bends easier. By utilizing this structural cushioning design, a sole structure may be configured to allow for a greater degree of deflection (compression) without requiring continuously increased loading, continuously increased stiffness, or both. Thus, the use of structural cushioning according to the present disclosure allows for comparable or superior energy storage within a sole structure during a gait cycle as conventional solid compressible materials, while providing an improved underfoot feel by allowing increased displacement with minimal increases to loading. Additionally, the use of cushioning structures according to the present disclosure allows for a highly tunable cushioning solution, whereby cushioning parameters can be selected by modifying any combination of strut thickness, strut angle, strut twist, material type, etc.

Additionally, material structures have been found that provide desirable cushioning properties across a wide range of displacements. For example, forming the structural cushioning components with an inner core having a first material first density and an outer sheath having a second density that is greater than the first density provides the structural cushioning elements with a composite structure, whereby the outer shell provides the strut with structural integrity while the lower density of the inner core minimizes overall weight. For example, the structural cushioning elements may be foamed using a supercritical foaming process producing microcellular to form the inner core and the outer sheath.

An aspect of the disclosure provides a sole structure for an article of footwear. The sole structure includes a cushioning element extending from an anterior end of the sole structure to a posterior end of the sole structure and including a top side, a bottom side formed on an opposite side from the top side, and a receptacle formed between the top side and the bottom side and including an upper receptacle surface and a lower receptacle surface spaced apart from and facing the upper receptacle surface. The sole structure further includes a support assembly disposed within the receptacle and including one or more support structures each including a plurality of flexible struts extending between the upper receptacle surface and the lower receptacle surface.

Aspects of the disclosure may include one or more of the following optional features. In some examples, the receptacle extends across an entire width of the cushioning element from a medial side of the sole structure to a lateral side of the sole structure. In some configurations, the receptacle is disposed in a forefoot region of the cushioning element.

In some implementations, the receptacle extends from a first end surface adjacent to a toe portion of the sole structure to a second end surface disposed in one of a forefoot region or a mid-foot region of the sole structure. Optionally, at least one of the first end surface or the second end surface is spaced apart from the support assembly. In some examples, the support assembly includes a first support structure disposed adjacent to a medial side of the receptacle and a second support structure disposed adjacent to a lateral side of the receptacle.

In some implementations, each support structure includes a base attached to the lower receptacle surface and a platform attached to the upper receptacle surface. In some configurations, each of the plurality of the struts extends between and connects the platform and the base. In some configurations, the plurality of the struts converge along a direction from the base to the platform.

In some configurations, the sole structure includes a plate including a first plate portion attached to the cushioning element in a toe portion, a second plate portion extending across the receptacle and defining the upper receptacle surface, and a third plate portion attached to the cushioning element in a mid-foot region of the sole structure.

Another aspect of the disclosure provides a sole structure for an article of footwear. The sole structure includes a cushioning element extending continuously from an anterior end of the sole structure to a posterior end of the sole structure and including a top side, a bottom side formed on an opposite side from the top side, and a receptacle disposed between the top side and the bottom side. The sole structure further includes a first support structure including a plurality of struts disposed within the receptacle adjacent to a lateral side of the sole structure. The sole structure, and a second support structure including a plurality of struts disposed within the receptacle adjacent to a medial side of the sole structure.

This aspect of the disclosure may include one or more of the following optional features. In some examples, the receptacle extends across an entire width of the cushioning element from the medial side to the lateral side. In some implementations, the receptacle is disposed in a forefoot region of the cushioning element.

In some examples, the receptacle extends from a first end surface adjacent to a toe portion of the sole structure to a second end surface disposed in one of a forefoot region or a mid-foot region of the sole structure. Optionally, at least one of the first end surface or the second end surface is spaced apart from each of the first support structure and the second support structure.

In some implementations, the receptacle includes an upper receptacle surface and a lower receptacle surface spaced apart from and facing the upper receptacle surface, and each support structure includes a base attached to the lower receptacle surface and a platform attached to the upper receptacle surface.

In some examples, the sole structure includes a plate having a first plate portion attached to the cushioning element in a toe portion, a second plate portion extending across the receptacle and defining the upper receptacle surface, and a third plate portion attached to the cushioning element in a mid-foot region of the sole structure.

Another aspect of the disclosure provides a sole structure for an article of footwear. The sole structure includes a cushioning element extending continuously from an anterior end of the sole structure to a posterior end of the sole structure and including a top side, a bottom side formed on an opposite side from the top side, and a receptacle formed between the top side and the bottom side and including an upper receptacle surface and a lower receptacle surface spaced apart from and facing the upper receptacle surface. The sole structure further includes a first support structure including a plurality of struts extending between the upper receptacle surface and the lower receptacle surface, and a second support structure including a plurality of struts extending between the upper receptacle surface and the lower receptacle surface.

This aspect of the disclosure may include one or more of the following optional features. In some examples, each support structure includes a base attached to the lower receptacle surface and a platform attached to the upper receptacle surface. In some implementations, the sole structure includes a plate including a first plate portion attached to the cushioning element in a toe portion, a second plate portion extending across the receptacle and defining the upper receptacle surface, and a third plate portion attached to the cushioning element in a mid-foot region of the sole structure.

Referring to FIGS. 1-4, an article of footwear 10 includes a sole structure 100 having an internal support assembly 200 and an upper 300 attached to the sole structure 100. The footwear 10 may further include an anterior end 12 associated with a forward-most point of the footwear 10, and a posterior end 14 corresponding to a rearward-most point of the footwear 10. As shown in FIG. 4, a longitudinal axis A₁₀ of the footwear 10 extends along a length of the footwear 10 from the anterior end 12 to the posterior end 14 parallel to a ground surface, and generally divides the footwear 10 into a medial side 16 and a lateral side 18. Accordingly, the medial side 16 and the lateral side 18 respectively correspond with opposite sides of the footwear 10 and extend from the anterior end 12 to the posterior end 14. As used herein, a longitudinal direction refers to the direction extending from the anterior end 12 to the posterior end 14, while a lateral direction refers to the direction transverse to the longitudinal direction and extending from the medial side 16 to the lateral side 18.

The article of footwear 10 may be divided into one or more regions. The regions may include a forefoot region 20, a mid-foot region 22, and a heel region 24. The forefoot region 20 may be subdivided into a toe portion 20_T corresponding with phalanges and a ball portion 20_B associated with metatarsal bones of a foot. The mid-foot region 22 may correspond with an arch area of the foot, and the heel region 24 may correspond with rear portions of the foot, including a calcaneus bone.

The upper 300 forms an enclosure having plurality of components that cooperate to define an interior void 302 and an ankle opening 304, which cooperate to receive and secure a foot for support on the sole structure 100. The upper 300 may be formed from one or more materials that are stitched or adhesively bonded together to define the interior void 302. Suitable materials of the upper 300 may include, but are not limited to, textiles, foam, leather, and synthetic leather. The example upper 300 may be formed from a combination of one or more substantially inelastic or non-stretchable materials and one or more substantially elastic or stretchable materials disposed in different regions of the upper 300 to facilitate movement of the article of footwear 10 between the tightened state and the loosened state. The one or more elastic materials may include any combination of one or more elastic fabrics such as, without limitation, spandex, elastane, rubber or neoprene. The one or more inelastic materials may include any combination of one or more of thermoplastic polyurethanes, nylon, leather, vinyl, or another material/fabric that does not impart properties of elasticity.

The sole structure 100 includes midsole a 102 configured to provide cushioning and support and an outsole 104 defining a ground-engaging surface (i.e., contacts the ground during a stance phase of a gait cycle) of the sole structure 100. Unlike conventional sole structures, which include monolithic midsoles and outsoles, the sole structure 100 of the present disclosure is configured as a composite structure including a plurality of components joined together. For example, the midsole 102 includes a resilient cushion or cushioning element 106, the support assembly 200, and a plate 110. The outsole 104 is attached to the midsole 102 to provide traction and abrasion resistance.

With reference to FIGS. 1 and 2, the cushioning element 106 of the midsole 102 extends from a first end 112 at the anterior end 12 of the footwear 10 to a second end 114 at the posterior end 14 of the footwear 10. The cushioning element 106 further includes a top side 116 facing the upper 300 and defining a profile of a footbed of the sole structure 100, a bottom side 118 formed on an opposite side of the cushioning element 106 from the top side 116 and defining a profile of the ground-contacting surface of the sole structure 100, and a peripheral side 120 extending from the top side 116 to the bottom side 118 and defining an outer peripheral profile of the sole structure 100.

While the cushioning element 106 may be formed as a monolithic structure including a homogenous elastomeric material, the cushioning element 106 of the present example is defined in terms of a plurality of portions or subcomponents. For example, the cushioning element 106 includes an upper cushion or cushioning member 130 disposed adjacent to the upper 300 and a lower cushion or cushioning member 132 disposed adjacent to the outsole 104. Each of the upper cushioning member 130 and the lower cushioning member 132 extends continuously from the first end 112 of the cushioning element 106 to the second end 114 of the cushioning element 106.

As described in greater detail below, the cushioning element 106 includes a receptacle 134 formed within the cushioning element 106 between the top side 116 and the bottom side 118 in the forefoot region 20. The receptacle 134 is configured to receive and support the support assembly 200 within the cushioning element 106. In other words, the cushioning element 106 extends above the support assembly 200 (i.e., between the support assembly 200 and the upper 300) and beneath the support assembly 200 (i.e., between the support assembly 200 and the outsole 104). While the receptacle 134 is defined by cooperating geometries of the upper cushioning member 130 and the lower cushioning member 132, as discussed more below, the receptacle 134 may be generally described as including an upper receptacle surface 136 defined by one of the plate 110 or the upper cushioning member 130 and an opposing lower receptacle surface 138, which is spaced apart from and faces the upper receptacle surface 136 to define a height H₁₃₄ of the receptacle.

Referring now to FIGS. 1-3, the upper cushioning member 130 extends continuously from the first end 112 of the cushioning element 106 to the second end 114 of the cushioning element 106. The upper cushioning member 130 includes the top side 116 of the cushioning element 106 and a lower side 140 formed on an opposite side of the upper cushioning member 130 than the top side 116. An upper portion of the peripheral side 120 connects the top side 116 to the lower side 140 and defines an outer peripheral profile of the upper cushioning member 130. As shown in FIG. 3, the top side 116 of the upper cushioning member 130 defines the footbed 142 of the sole structure 100. Further, the top side 116 may include a peripheral flange 144 that extends outwardly from a peripheral portion of the footbed 142 around the heel region 24 of the sole structure 100 to provide increased stability and cushioning around the heel portion. Optionally, the lower side 140 of the upper cushioning member 130 includes an upper plate pocket 146 configured to receive an upper portion of the plate 110 when the sole structure 100 is assembled.

Referring still to FIGS. 1-3, the lower cushioning member 132 extends continuously from the first end 112 of the cushioning element 106 to the second end 114 of the cushioning element 106. The lower cushioning member 132 may be described as including the bottom side 118 of the cushioning element 106 and an upper side 150 formed on an opposite side of the lower cushioning member 132 than the bottom side 118. A lower portion of the peripheral side 120 connects the bottom side 118 and the upper side 150 and defines an outer peripheral profile of the lower cushioning member 132. When the sole structure 100 is assembled, the upper side 150 of the lower cushioning member 132 faces and is attached to the lower side 140 of the upper cushioning member 130 to form the cushioning element 106.

The upper side 150 of the lower cushioning member 132 may optionally include a lower plate pocket 152 configured to receive a lower portion of the plate 110 when the sole structure 100 is assembled. Because the lower cushioning member 132 may include the receptacle 134 formed in the upper side 150, a first portion of the lower pocket 152 may be formed in the upper side 150 in the toe portion 20_T and a second portion of the lower pocket 152 may be formed in the upper side 150 in the mid-foot region 22 and the heel region 24. Thus, when the sole structure 100 is assembled, a top portion of the plate 110 is received by the upper plate pocket 146 formed in the lower side 140 of the upper cushioning member 130 and a bottom portion of the plate 110 is received by the portions of the lower plate pocket 152 formed in the upper side 150 of the lower cushioning member 132. Here, the lower portion of the plate 110 may be exposed within the receptacle 134 between the portions of the lower plate pocket 152 formed in the toe portion 20_T and the mid-foot region 22.

Although the lower cushioning member 132 is formed as a continuous structure extending from the first end 112 to the second end 114, the lower cushioning member 132 may be described as including an anterior support segment 154 disposed adjacent to the first end 112, a posterior support segment 156 disposed adjacent to the second end 114, and a tray 158 connecting the anterior support segment 154 and the posterior support segment 156. The anterior support segment 154 and the posterior support segment 156 each define a first thickness T_132-1 of the lower cushioning member 132 extending from the bottom side 118 to the upper side 150 and the tray 158 defines a second thickness T_132-2 that is less than the first thickness T_132-1 in the ball portion 20_B of the lower cushioning member 132. Accordingly, the different thicknesses T_132-1, T_132-2 of the lower cushioning member 132 cooperate to define the receptacle 134 in the ball portion 20_B of the lower cushioning member 132.

As shown, the receptacle 134 of the sole structure 100 extends along the direction of the longitudinal axis A₁₀ from a first end surface 160 to a second end surface 162 that faces the first end surface 160. Thus, the first end surface 160 defines a posterior end of the anterior support segment 154 and the second end surface 162 defines an anterior end of the posterior support segment 156. The receptacle 134 is further defined by a recessed support surface 164 connecting the first end surface 160 and the second end surface 162. In the illustrated example, each of the surfaces 160, 162, 164 extends continuously through an entire width of the midsole 102 from the medial side 16 to the lateral side 18 such that the receptacle 134 effectively forms a channel extending across the width of the sole structure 100.

In the illustrated example, the first end surface 160 is disposed between the toe portion 20_T and the ball portion 20_B and the second end surface 162 is disposed between the ball portion 20_B and the mid-foot region 22. As best shown in FIG. 3, a distance from the first end surface 160 to the second end surface 162 defines a length L₁₃₄ of the receptacle 134, which tapers along a direction from the upper side 150 to the recessed support surface 164. In other words, the length L₁₃₄ of the receptacle 134 is greater at the upper side 150 than at the recessed support surface 164 to provide the receptacle with a generally trapezoidal cross-sectional profile.

The tapered length L₁₃₄ of the receptacle 134 is defined by forming each of the first end surface 160 and the second end surface 162 at an oblique angle θ₁₆₀, θ₁₆₂ angle relative to a central axis A₁₃₄. In other words, the first end surface 160 and the second end surface 162 may be described as extending at obtuse angles relative to the recessed support surface 164. For example, the first end surface 160 extends at a first oblique angle θ₁₆₀ in a direction towards the first end 112 from the recessed support surface 164 to the upper side 150 and the second end surface 162 extends at a second oblique angle θ₁₆₂ in a direction towards the second end 114 from the recessed support surface 164 to the upper side 150. Optionally, one or both of the first end surface 160 and the second end surface 162 may include a concave profile along the direction from the recessed support surface 164 to the upper side 150. For example, the first end surface 160 is shown as including a continuous curvature from the recessed support surface 164 to the upper side 150. Conversely, the second end surface 162 includes a substantially straight or flat portion extending from the upper side 150 and a concave transition portion connecting the straight portion and the recessed support surface 164. In other examples, either one or both of the end surfaces 160, 162 may be continuously curved or include a straight portion.

Referring to FIGS. 1 and 2, when the sole structure 100 is assembled, the length L₁₃₄ of the receptacle 134 is sufficient to provide gaps 166, 168 between the support assembly 200 and the respective end surfaces 160, 162. The gaps 166, 168 include a first gap 166 disposed between the first end surface 160 and the support assembly 200 and a second gap 168 disposed between the second end surface 162 and the support assembly 200. The gaps 166, 168 provide an expansion space between the support assembly 200 and the lower cushioning member 132. Thus, when the forefoot region 20 of the sole structure 100 is compressed, the support assembly 200 and the lower cushioning member 132 may deform and extend into the gaps 166, 168 without contacting each other or the end surfaces 160, 162.

The upper receptacle surface 136 is spaced apart from the lower receptacle surface 138 by a distance defining a height H₁₃₄ of the receptacle 134. As shown, the height H₁₃₄ of the receptacle 134 corresponds to a thickness T₁₀₈ of the support assembly 200 such that the support assembly 200 contact a bottom side of the plate 110 when the sole structure 100 is assembled. The tray 158 may further include one or more recessed sockets 170 formed in the recessed support surface 164. Each of the one or more sockets 170 is configured to receive a bottom side of a corresponding one of the support structures 202 within receptacle 134. Thus, the sockets 170 cooperate with the plate 110 and/or the upper cushioning member 130 to secure top and bottom sides of the support assembly 200 within the receptacle 134. In the illustrated example, the tray 158 includes a pair of the sockets 170 such that the support assembly 200 sits flush with the upper side 150 of the lower cushioning member 132 when the sole structure 100 is assembled. Here, a first one of the sockets 170 is disposed adjacent to the medial side 16 of the sole structure 100 in the ball portion 20_B and a second one of the sockets 170 is disposed adjacent to the lateral side 18 of the sole structure 100 in the ball portion 20_B. As shown, the sockets 170 are exposed along the lateral and medial peripheral sides 120 and at the terminal, such that the support assembly 200 is displayed and unconstricted along the sides 16, 18 when the sole structure 100 is assembled.

Optionally, the tray 158 may include a tongue 172 extending at least partially between the sockets 170. In the illustrated example, the tongue 172 extends from the second end surface 162 of the receptacle 134 to a terminal end 174 disposed between the sockets 170. The tongue 172 may have a tapered width along the direction from the second end surface 162 to the terminal end 174. The receptacle 134 may also include a recess or relief 175 formed in the first end surface 160, opposite the tongue 172. In the illustrated example, the relief 175 separates the posterior end of the anterior support segment 154 into medial and lateral segments that can articulate independently, thereby improving flexibility of the sole structure 100 across the forefoot region 20.

With continued reference to FIGS. 3 and 4, the posterior support segment 156 of the lower cushioning member 132 extends through the heel region 24 from the second end 114 of the cushioning element 106 to the second end surface 162 in the mid-foot region 22. The posterior support segment 156 may optionally include an elongate channel 176 formed in the bottom side 118 and extending from the mid-foot region 22 to the heel region 24. The channel 176 has a tapered or triangular cross section extending from an opening in the bottom side 118 to an apex between the bottom side 118 and the upper side 150. The channel 176 defines articulable medial and lateral lobes 178 extending along the length of the posterior support segment 156.

As described above, the components 130, 132 of the cushioning element 106 are formed of a resilient polymeric material, such as foam or rubber, to impart properties of cushioning, responsiveness, and energy distribution to the foot of the wearer. In the illustrated example, the upper cushioning member 130 includes a first foam material and the lower cushioning member 132 includes a second foam material. For example, the upper cushioning member 130 may include first foam materials providing greater cushioning and impact distribution, while the lower cushioning member 130 includes a foam material having a greater hardness or stiffness in order to provide increased stability to the bottom of the sole structure 100. Furthermore, and as discussed below, the tray 158 of the lower cushioning member 132 may have a greater hardness to maximize displacement of the support assembly 200 when the forefoot region 20 is compressed.

Example resilient polymeric materials for the cushioning element 106 may include those based on foaming or molding one or more polymers, such as one or more elastomers (e.g., thermoplastic elastomers (TPE)). The one or more polymers may include aliphatic polymers, aromatic polymers, or mixtures of both; and may include homopolymers, copolymers (including terpolymers), or mixtures of both.

In some aspects, the one or more polymers may include olefinic homopolymers, olefinic copolymers, or blends thereof. Examples of olefinic polymers include polyethylene, polypropylene, and combinations thereof. In other aspects, the one or more polymers may include one or more ethylene copolymers, such as, ethylene-vinyl acetate (EVA) copolymers, EVOH copolymers, ethylene-ethyl acrylate copolymers, ethylene-unsaturated mono-fatty acid copolymers, and combinations thereof.

In further aspects, the one or more polymers may include one or more polyacrylates, such as polyacrylic acid, esters of polyacrylic acid, polyacrylonitrile, polyacrylic acetate, polymethyl acrylate, polyethyl acrylate, polybutyl acrylate, polymethyl methacrylate, and polyvinyl acetate; including derivatives thereof, copolymers thereof, and any combinations thereof.

In yet further aspects, the one or more polymers may include one or more ionomeric polymers. In these aspects, the ionomeric polymers may include polymers with carboxylic acid functional groups, sulfonic acid functional groups, salts thereof (e.g., sodium, magnesium, potassium, etc.), and/or anhydrides thereof. For instance, the ionomeric polymer(s) may include one or more fatty acid-modified ionomeric polymers, polystyrene sulfonate, ethylene-methacrylic acid copolymers, and combinations thereof.

In further aspects, the one or more polymers may include one or more styrenic block copolymers, such as acrylonitrile butadiene styrene block copolymers, styrene acrylonitrile block copolymers, styrene ethylene butylene styrene block copolymers, styrene ethylene butadiene styrene block copolymers, styrene ethylene propylene styrene block copolymers, styrene butadiene styrene block copolymers, and combinations thereof.

In further aspects, the one or more polymers may include one or more polyamide copolymers (e.g., polyamide-polyether copolymers) and/or one or more polyurethanes (e.g., cross-linked polyurethanes and/or thermoplastic polyurethanes). Alternatively, the one or more polymers may include one or more natural and/or synthetic rubbers, such as butadiene and isoprene.

When the resilient polymeric material is a foamed polymeric material, the foamed material may be foamed using a physical blowing agent which phase transitions to a gas based on a change in temperature and/or pressure, or a chemical blowing agent which forms a gas when heated above its activation temperature. For example, the chemical blowing agent may be an azo compound such as azodicarbonamide, sodium bicarbonate, and/or an isocyanate.

In some embodiments, the foamed polymeric material may be a crosslinked foamed material. In these embodiments, a peroxide-based crosslinking agent such as dicumyl peroxide may be used. Furthermore, the foamed polymeric material may include one or more fillers such as pigments, modified or natural clays, modified or unmodified synthetic clays, talc glass fiber, powdered glass, modified or natural silica, calcium carbonate, mica, paper, wood chips, and the like.

The resilient polymeric material may be formed using a molding process. In one example, when the resilient polymeric material is a molded elastomer, the uncured elastomer (e.g., rubber) may be mixed in a Banbury mixer with an optional filler and a curing package such as a sulfur-based or peroxide-based curing package, calendared, formed into shape, placed in a mold, and vulcanized.

In another example, when the resilient polymeric material is a foamed material, the material may be foamed during a molding process, such as an injection molding process. A thermoplastic polymeric material may be melted in the barrel of an injection molding system and combined with a physical or chemical blowing agent and optionally a crosslinking agent, and then injected into a mold under conditions which activate the blowing agent, forming a molded foam.

Optionally, when the resilient polymeric material is a foamed material, the foamed material may be a compression molded foam. Compression molding may be used to alter the physical properties (e.g., density, stiffness and/or durometer) of a foam, or to alter the physical appearance of the foam (e.g., to fuse two or more pieces of foam, to shape the foam, etc.), or both.

The compression molding process desirably starts by forming one or more foam preforms, such as by injection molding and foaming a polymeric material, by forming foamed particles or beads, by cutting foamed sheet stock, and the like. The compression molded foam may then be made by placing the one or more preforms formed of foamed polymeric material(s) in a compression mold, and applying sufficient pressure to the one or more preforms to compress the one or more preforms in a closed mold. Once the mold is closed, sufficient heat and/or pressure is applied to the one or more preforms in the closed mold for a sufficient duration of time to alter the preform(s) by forming a skin on the outer surface of the compression molded foam, fuse individual foam particles to each other, permanently increase the density of the foam(s), or any combination thereof. Following the heating and/or application of pressure, the mold is opened and the molded foam article is removed from the mold.

With continued reference to FIGS. 3 and 4, the plate 110 extends from a first end 180 in the toe portion 20_T to a second end 182 in the heel region 24. The plate 110 includes a top side 184 and a bottom side 186 formed on an opposite side than the top side 184. A distance from the top side 184 to the bottom side 186 defines a thickness of the plate 110. An outer periphery extends between the top side 184 and the bottom side 186 and defines a peripheral profile of the plate 110, which corresponds to a peripheral profile of the upper and lower pockets 146, 152. The plate 110 may be embedded between the upper cushioning member 130 and/or the lower cushioning member 132 such that the top side 184 of the plate 110 is received in the upper plate pocket 146 and the bottom side 186 of the plate 110 is received in the lower plate pocket 152. Here, the first end 180 of the plate 110 is received within a portion of the lower pocket 152 defined by the anterior support segment 154 and the second end 182 of the plate 110 is received within a portion of the lower pocket 152 defined by the posterior support segment 156. Thus, the bottom side 186 of the plate 110 is exposed (i.e., visible) to the ground surface through the receptacle 134 between the anterior support segment 154 and the posterior support segment 156.

The plate 110 includes a material providing relatively high strength and stiffness, such as polymeric material and/or composite materials. In some examples, the plate 110 is a composite material manufactured using fiber sheets or textiles, including pre-impregnated (i.e., “prepreg”) fiber sheets or textiles. Alternatively or additionally, the plate 110 may be manufactured by strands formed from multiple filaments of one or more types of fiber (e.g., fiber tows) by affixing the fiber tows to a substrate or to each other to produce a plate having the strands of fibers arranged predominately at predetermined angles or in predetermined positions. When using strands of fibers, the types of fibers included in the strand can include synthetic polymer fibers which can be melted and re-solidified to consolidate the other fibers present in the strand and, optionally, other components such as stitching thread or a substrate or both. Alternatively or additionally, the fibers of the strand and, optionally the other components such as stitching thread or a substrate or both, can be consolidated by applying a resin after affixing the strands of fibers to the substrate and/or to each other.

In some implementations, the plate 110 includes a substantially uniform thickness. In some examples, the thickness of the plate 110 ranges from about 0.6 millimeters (mm) to about 3.0 mm. In one example, the thickness of the plate 110 is substantially equal to one 1.0 mm. In other implementations, the thickness of the plate 110 is non-uniform such that the plate 110 may have a greater thickness in one region 20, 22, 24 of the sole structure 100 than the thicknesses in the other regions 20, 22, 24.

Referring now to FIG. 3, the support assembly 200 includes a pair of support structures 202 received within the sockets 170 of the receptacle 134. As shown, each of the support structures 202 includes a plurality of struts 204 arranged in an annular array about a central axis A₂₀₂ of the support structure 202 and each extending continuously between an upper platform 206 at a first end and a lower base 208 at an opposite end. The platform 206 is attached to the upper receptacle surface 136 defined by the upper cushioning member 130 or the plate 110, while the base 208 is attached to the lower receptacle surface 138 defined by the tray 158. In this example, each of the struts 204 extends continuously along a longitudinal axis A₂₀₄ from an upper distal end 210 at the platform 206 to a lower distal end 210 at the base 208. Here, one or more of the struts 204 may converge with each other along a direction extending between the base 208 and the platform 206. For example, in the illustrated configuration, the support structures 202 include struts 204 having longitudinal axes A₂₀₄ that converge with each other along a direction from the base 208 to the platform 206.

In some examples, discussed in greater detail below with respect to FIGS. 9-19B, all of the struts 204 of the support structure 202 converge and intersect at respective vertices of single platform 206 to form a pyramidal structure. In other words, the struts 204 are arranged as an array and each extend from a first end of the support structure at the base 208 to a second end of the support structure 202 at the platform 206. For example, the illustrated support structures 202 include a hexagonal platform 206 having six vertices and six corresponding struts 204 each having an upper distal end 210 attached to the platform 206 at a respective one of the vertices. The platforms 206 of the support structures 202 cooperate with each other to define a support surface of the support assembly 200, which interfaces with upper receptacle surface 136.

With continued reference to FIG. 3, the lower distal ends 212 of the struts 204 attach to the base 208 of the support structure 202 at respective nodes 214. Here, the plurality of nodes 214 of each support structure 202 are connected to each other by lower chords or base members 216 to define the base 208 at a lower end of each support structure 202. The bases 208 of the support structures 202 cooperate with each other to define a lower support portion of the support assembly 200 that engages with the tray 158 of the cushioning element 106. As shown, the base members 216 of each support structure 202 are configured in a hexagonal shape, whereby the nodes 214 correspond with vertices of the base 208.

As provided above, the support structures 202 are arranged within the midsole 102 such that the struts 204 extend continuously between the upper receptacle surface 136 and the lower receptacle surface 138. In other words, each strut 204 only includes a pair of attachment points, one at each of the distal ends 210, 212 such that an intermediate portion (i.e., the portion extending between the distal ends 210, 212 of each strut 204) is unconstrained and is free to flex or bend. Thus, each strut 204 may be configured to act as a mechanical spring element, whereby a combination of the geometry and the material of the strut 204 is selected to impart desired properties of cushioning and responsiveness. Various configurations of struts 204 and the associated properties are discussed in greater detail below with respect to FIGS. 11A-18B. For example, as detailed with respect to FIGS. 18A and 18B, the struts 204, the base members 216, or other portions of the support structures 202 may be formed as composite structures having an inner core 1018 formed of first material and an outer sheath 1020 formed of a second material. At least a portion of the support structures 202, the struts 204, and/or the base members 216 may be formed using a supercritical foaming process producing microcellular foam to form the inner core 1018 and the outer sheath 1020. While the illustrated example contemplates forming the structural cushioning components using a supercritical foaming, the structural cushioning components may also be formed using other suitable techniques, such as thermoforming (e.g. vacuum thermoforming), blow molding, extrusion, injection molding, vacuum molding, rotary molding, transfer molding, pressure forming, heat sealing, casting, low-pressure casting, spin casting, reaction injection molding, radio frequency (RF) welding, additive manufacturing, and the like.

With particular reference to FIGS. 5 and 6, an article of footwear 10a is provided and includes a sole structure 100a including a support assembly 200a and the upper 300. In view of the substantial similarity in structure and function of the components associated with the article of footwear 10a with respect to the article of footwear 10, like reference numerals are used hereinafter and in the drawings to identify like components while like reference numerals containing letter extensions are used to identify those components that have been modified.

The sole structure 100a includes a midsole 102a configured to provide cushioning and support and an outsole 104a defining a ground-engaging surface (i.e., contacts the ground during a stance phase of a gait cycle) of the sole structure 100a. Unlike conventional sole structures, which include monolithic midsoles and outsoles, the sole structure 100a of the present disclosure is configured as a composite structure including a plurality of components joined together. For example, the midsole 102a includes a resilient cushion or cushioning element 106a, the support assembly 200a, and a plate 110a. The outsole 104a is attached to the midsole 102a to provide traction and abrasion resistance.

With reference to FIGS. 1 and 2, the cushioning element 106a of the midsole 102a extends from a first end 112a at the anterior end 12 of the footwear 10a to a second end 114a at the posterior end 14 of the footwear 10a. The cushioning element 106a further includes the top side 116 facing the upper 300 and defining a profile of a footbed of the sole structure 100a, a bottom side 118a formed on an opposite side of the cushioning element 106a from the top side 116 and defining a profile of the ground-contacting surface of the sole structure 100a, and a peripheral side 120a extending from the top side 116 to the bottom side 118 and defining an outer peripheral profile of the sole structure 100a. As shown previously in FIG. 3, the top side 116 of the cushioning element 106a defines the footbed 142 of the sole structure 100a. Further, the top side 116 may include the peripheral flange 144 that extends outwardly from a peripheral portion of the footbed 142 around the heel region 24 of the sole structure 100a to provide increased stability and cushioning around the heel portion.

As described in greater detail below, the cushioning element 106a includes a receptacle 134a formed within the cushioning element 106a between the top side 116 and the bottom side 118 in the forefoot region 20. The receptacle 134a is configured to receive and support the support assembly 200a within the cushioning element 106a. In other words, the cushioning element 106a extends above the support assembly 200a (i.e., between the support assembly 200a and the upper 300) and beneath the support assembly 200a (i.e., between the support assembly 200a and the outsole 104a). As shown, the receptacle includes an upper receptacle surface 136a extending from a first end 135a of the receptacle 134a adjacent to the toe portion 20_T to a second end 137a of the receptacle 134a in the midfoot region 22. The receptacle 134a further includes a lower receptacle surface 138a that is spaced apart from and facing the upper receptacle surface 136a, and extends continuously from the first end 135a of the receptacle 134a to the second end 137a of the receptacle 134a. Accordingly, the upper receptacle surface 136a and the lower receptacle surface 138a intersect at the respective first and second ends 135a, 137a of the receptacle 134a.

As shown, the receptacle 134a of the sole structure 100a extends along the direction of the longitudinal axis from a first end surface 160a to a second end surface 162a that faces the first end surface 160a. The receptacle 134a is further defined by a recessed support surface 164a connecting the first end surface 160a and the second end surface 162a. In the illustrated example, each of the surfaces 160a, 162a, 164a extends continuously through an entire width of the midsole 102a from the medial side 16 to the lateral side 18 such that the receptacle 134a effectively forms a channel extending across the width of the sole structure 100a.

In the illustrated example, the first end surface 160a is disposed between the toe portion 20_T and the ball portion 20_B and the second end surface 162a is disposed between the ball portion 20_B and the mid-foot region 22. Optionally, one or both of the first end surface 160a and the second end surface 162a may include a concave profile along the direction from the recessed support surface 164a to the upper receptacle surface 136a. For example, the first end surface 160a is shown as including a continuous curvature from the recessed support surface 164a to the upper side 150. Conversely, the second end surface 162a includes a substantially straight or flat portion extending from the upper side 150 and a concave transition portion connecting the straight portion and the recessed support surface 164a. In other examples, either one or both of the end surfaces 160a, 162a may be continuously curved or include a straight portion.

Referring to FIGS. 5 and 6, when the sole structure 100a is assembled, the length of the receptacle 134a (i.e., distance from the first end 135a to the second end 137a) is sufficient to provide gaps 166a, 168a between the support assembly 200a and the respective end surfaces 160a, 162a. The gaps 166a, 168a include a first gap 166a disposed between the first end surface 160a and the support assembly 200a and a second gap 168a disposed between the second end surface 162a and the support assembly 200a. The gaps 166a, 168a provide an expansion space between the support assembly 200a and the lower cushioning member 132. Thus, when the forefoot region 20 of the sole structure 100a is compressed, the support assembly 200a and the lower cushioning member 132 may deform and extend into the gaps 166a, 168a without contacting each other or the end surfaces 160a, 162a.

The recessed support surface 164a is spaced apart from the upper receptacle surface 136a by a distance defining a height H_134a of the receptacle 134a. As shown, the height H_134a of the receptacle 134a corresponds to a thickness T₁₀₈ of the support assembly 200a such that the support assembly 200a contact a bottom side of the plate 110a when the sole structure 100a is assembled. The tray 158 may further include one or more of the recessed sockets (not shown, but similar to sockets) formed in the recessed support surface 164a. Each of the one or more sockets is configured to receive a bottom side of a corresponding one of the support structures 202 within receptacle 134a. Thus, the sockets cooperate with the plate 110a and/or the upper receptacle surface 136 to secure top and bottom ends of the support assembly 200a within the receptacle 134a. In the illustrated example, the tray 158a includes a first one of the sockets is disposed adjacent to the medial side 16 of the sole structure 100a in the ball portion 20_B and a second one of the sockets is disposed adjacent to the lateral side 18 of the sole structure 100a in the ball portion 20_B. As shown, the sockets are exposed along the lateral and medial peripheral sides 120a, such that the support structures 202 are displayed and unconstricted along the sides 16, 18 when the sole structure 100a is assembled.

As described above, the cushioning element 106a is formed of a resilient polymeric material, such as foam or rubber, to impart properties of cushioning, responsiveness, and energy distribution to the foot of the wearer. Optionally, the cushioning element 106a may include an upper cushioning member having a first foam material and a lower cushioning member includes a second foam material, similar to the cushioning element 106a discussed previously.

With continued reference to FIGS. 5 and 6, the plate 110a is formed substantially similar to the plate 110a and extends through the receptacle 134a, along the upper receptacle surface 136a. Ends of the plate 110a extend into the toe portion 20_T and the heel region 24 and are embedded within the material of the cushioning element 106a. As discussed above, the cushioning element 106a may be constructed as a composite structure including upper and lower cushioning members, whereby the plate 110a is received between the cushioning members when the sole structure is assembled.

Referring still to FIGS. 5 and 6, the support assembly 200a of the sole structure 100a includes a pair of the support structures 202 as discussed previously. In this example, the support structures 202 are inverted such that the platforms 206 face the recessed support surface 164a of the receptacle 134a and the bases 208 face the upper receptacle surface 136a. In this example, the base 208 of each of the support structures 202 may be directly attached to a bottom side 186a of the plate 110a that extends through the receptacle 134a and defines the upper receptacle surface 136a. Conversely, the platform 206 of each support structure 202 is received within one of the sockets formed in the tray 158a of the cushioning element 106a.

With particular reference to FIGS. 7 and 8, an article of footwear 10b is provided and includes a sole structure 100b including a support assembly 200b and the upper 300. In view of the substantial similarity in structure and function of the components associated with the article of footwear 10b with respect to the article of footwear 10, like reference numerals are used hereinafter and in the drawings to identify like components while like reference numerals containing letter extensions are used to identify those components that have been modified.

The sole structure 100b includes the midsole 102 discussed above with respect to the article of footwear 10. In this example, the support assembly 200b includes support structures 202b substantially similar to the support structures 202 discussed previously, but further including a foam insert 230 received within the support structure 202b. Here, the foam insert 230 cooperates with the struts 204 of the support structure 202b to provide complimentary cushioning properties, whereby the struts 204 provide support through an initial stage of compression of the support structure 202a and the foam insert 230 provides support through a second stage of compression of the support structure 202a. Thus, the foam insert 230 and the struts 204 cooperate to provide consistent loading and support throughout the full range of compression of the support structure 202a.

With particular reference to FIG. 9, an article of footwear 10c is provided and includes a sole structure 100c including a support assembly 200c and the upper 300. In view of the substantial similarity in structure and function of the components associated with the article of footwear 10c with respect to the article of footwear 10, like reference numerals are used hereinafter and in the drawings to identify like components while like reference numerals containing letter extensions are used to identify those components that have been modified.

The sole structure 100c includes the midsole 102 discussed above with respect to the article of footwear 10. In this example, the support assembly 200c includes support structures 202c having a plurality of helically-shaped struts 204c extending from an annular base 208c to a platform 206. As shown, the struts 204c and the platform 206c are formed as integrated structures, whereby the struts 204c are substantially continuous with the platform 206c to define a hemispherical support structure 202c. In this example, the struts 204c are formed with polygonal or rectangular cross sections that extend from the base 208c to the platform 206c. Optionally, the struts 204c may taper in width W_204c along the direction from the base 208c to the platform 206c. The helical design of the struts 204c is configured to impart a twisting motion as the support structure 202c is compressed under load, whereby the platform 206c rotates relative to the base 208c as the support structure is compressed.

Referring to FIGS. 10-13B, performance parameters of representative examples of support structures 202-202g, 202-1-202-8 (FIG. 11A) and the corresponding performance parameters are illustrated. FIG. 10 initially illustrates representative testing data showing cushioning characteristics for a sample support structure constructed according to the principles disclosed herein compared against an air-filled bladder and a foam puck having substantially similar thicknesses. In FIG. 10, cushioning characteristics for each of the air-filled bladder, the foam puck, and the support structure are defined in terms of (i) energy efficiency and (ii) linearity. Here, efficiency is measured as a ratio of energy returned to energy input for each loading cycle. For example, to determine the energy efficiency for a given structure, the area of the graph under the unloading curve (i.e., the lower line for each material) is divided by the area of the graph under the loading curve (i.e, the upper line for each material). In the illustrated example, the air-filled bladder, the foam puck, and the support structure had efficiencies of 93.1%, 85.5%, and 80.2%, respectively. Thus, the tested support structure had a lower efficiency than the foam and the air-filled bladders of comparable thickness. However, as discussed below, efficiencies of the support structures can be tune by modifying geometries and materials of the support structure.

Referring still to FIG. 10, the cushioning characteristic of linearity is defined as the area of the graph under a given F/D curve (e.g., loading curve, unloading curve) divided by the area of the graph under a corresponding theoretical line representing a linear spring force extending between the fully unloaded point and the fully loaded point of the curve. While efficiency represents the relative energy returned (i.e., energy in/energy out) during a compression cycle, linearity is representative of the total energy stored and returned by a structure. Thus, greater linearity value corresponds to a greater absolute energy storage and return capacity for a material or structure. Energy stored by a material is calculated by taking the average of the linearity for the loading curve (i.e., loading linearity), while energy returned is represented by linearity for the unloading curve (i.e., unloading linearity), where each of the loading linearity and the unloading linearity are calculated by dividing the area under the respective curve by the area under the theoretical linear spring rate.

In the illustrated example, the air-filled bladder has an unloading linearity value of 0.988, which corresponds to the area under the unloading curve of the air-filled bladder being slightly less than the area under the theoretical linear spring rate, as shown in FIG. 10. The foam puck has an unloading linearity value of 0.794, which corresponds to the area under the unloading curve of the foam puck being substantially less than the area under the theoretical linear spring rate. Finally, the tested support structure had an unloading linearity value of 1.116, which corresponds to the area under the unloading curve of the foam puck being substantially greater than the area under the theoretical linear spring rate. Thus, while the support structure tested had a slightly lower efficiency than the air-filled bladder and the foam puck having the same thicknesses, the support structure was capable of storing and returning greater overall amount of energy throughout the compression cycle.

As discussed below with respect to FIGS. 11A-13B, the efficiency, linearity, and other cushioning characteristics (e.g., underfoot feel) of the support structures can be tuned by leveraging various combinations of design changes to the support structures, as summarized in Table 1:

TABLE 1
Support Structure Design Parameters

	Design Change	Result to Structure
	Increase Twist	Softer Structure
	Increase Diameter	Stiffer Structure
	Increase Number of Struts	Stiffer Structure
	Increase Strut Length	Softer and More Efficient Structure
	Scale Up (uniform xyz)	Scaled F/D Curve
	Material Durometer Change	Proportional Change to F/D Curve
	Constrain Structure	Increased Efficiency
	Point Loading	Increased Energy Return

Referring now to FIGS. 11A and 11B, representative testing data is provided showing the relative impact of changing geometries of the struts of a support structure. FIG. 11A shows eight examples of support structures 202-1-202-8 according to the present disclosure, whereby each support structure has a modified geometry. The support structure 202-1 includes a conventional arcuate strut 204 extending between the base 208 and the platform 206, while structures 202-2-202-4 are constructed with struts having intermediate elbows 222 or pre-bends formed between the upper distal end and the lower distal end. Structures 202-2-202-4 vary in the degree that the elbow 222 is pre-bent, with the degree of pre-bend progressively increasing from 202-2 to 202-4. In these examples, the struts 204a-204c extend from the base at an oblique angle, but bend back towards the platform in an opposite direction, whereby the platform 206 and the base 208 have the same rotational orientation or clocking relative to a central axis of the support structure.

Structures 202-6-202-8 (labeled B6, B7, B8) are modified by introducing rotational offset or twist between the base 208 and the platform 206, whereby the struts 204c-204f extend at an oblique angle from the base 208 to the platform 206. Thus, the struts 204d-204f extend away from the base at an oblique twist angle (discussed more with respect to FIGS. 17A-17E) to the platform 206. Here, the platform 206 is rotated relative to the base 208, whereby vertices of the platform 206 are rotationally offset from the vertices or nodes of the base 208.

As shown in the graph of FIG. 11B, introducing the elbows 222 into the geometry of the struts 204a-204c has variable impacts on efficiency and unloading linearity. Particularly, increasing the degree of the pre-bend causes efficiency to increase while causing unloading linearity to decrease. Conversely, test data shows that introducing a twist, as done in support structures 202-6-202-8, causes efficiency and linearity to both decrease in connection with increased twist angle.

Referring to FIGS. 12A and 12B, another example of representative testing data is provided to illustrate the relative impact of changing a location of an elbow 222 on a strut 204. For example, the support structure 202d (labeled C18) includes an elbow 222g formed in an intermediate portion of the strut 204g, substantially centered between the upper distal end 210g and the lower distal end 212g. Support structure 202e (labeled C21) is formed with the elbows 222h closer to the upper distal ends 210h of the struts 204h. As shown in FIG. 12B, moving the elbow towards an intermediate position along the strut (C18) results in increased efficiency relative to moving the elbow 222 closer to one of the distal ends 210, 212. However, while not represented numerically, the graphs for the respective materials show that loading linearity (i.e., energy storage represented by area under the loading curve) for the support strut 204e having the elbows 222h located adjacent to the platform 206e is greater than linearity for each of the support strut 202g, the foam, and the air-filled bladder. Thus, FIG. 12B provides a graphical representation of the strain, efficiency, and linearity of the various components that may be combined or stacked within the sole structures 100-100b discussed previously. FIG. 12C shows a graphical representation of the loading and unloading curves for each of the support structures 202d, 202e compared against the control support structure discussed previously with respect to FIG. 10. Here, the graph and resulting data shows that introducing the elbows 222 provides increased efficiency and reduced unloading linearity (i.e., total energy returned) compared to the control support structure with no elbows.

Referring to FIGS. 13A and 13B, another example of representative testing data is provided to illustrate the impact of including a twisted support structure 202f compared to a support structure 202g including elbows 222i. Support structure 202f (labeled B7) is formed with struts 204e that are oriented in a twisted configuration without elbows while the support structure 202g is formed with struts 204i that are formed with elbows 222i in an intermediate portion of the strut 204i. As shown in FIG. 13B, including elbows 222i at an intermediate position along the strut 204i results in increased efficiency relative to a comparable support structure 202f with no elbows and a twisted orientation.

Referring to FIGS. 14A-14E, a generic example of the reaction of a support structure 1000 in response to a load L is illustrated. In this example, the support structures 1000 are formed as four-sided pyramids including a square base 1012a and four struts 1002 each extending from a lower distal end 1008 attached at a respective node 1004 formed at a corner of the base 1012a to an upper distal end 1006 attached to a common upper node 1004. However, the principles illustrated in FIGS. 14A-14C would apply to support structure 1000 having other configurations discussed herein. In FIG. 14A, the support structure 1000 is shown in a natural or relaxed state, wherein no external loads L (e.g., compression by foot) are applied to the support structure 1000 and the support structure 1000 has a height H₁₀₀₀ measured from the base 1012 to the upper node 1004. Here, the struts 1002 are each in a straight, non-deformed state between the base 1012 and the upper node 1004.

In FIG. 14B, the support structure 1000 is shown in a first reactive state, whereby a first compressive load L₁ is applied to the upper node 1004 along the direction of the axis A₁₀₀₀. Under the first load L₁, the upper node 1004 is displaced by a distance D₁ and the support structure 1000 is compressed to a reduced height H_1000-1 corresponding to the first load L₁. Described differently, when the load L₁ is applied to the upper node 1004, the load L₁ is distributed among each of the struts 1002 and is transferred along the longitudinal axes A₁₀₀₂ of each to each of the struts 1002 to the base 1012. As the load L₁ increases, the struts 1002 react by bending or deflecting along their respective axes A₁₀₀₂. In other words, each strut 1002 is caused to bow along its length between the upper distal end 1006 and the lower distal end 1008. This deflection may result in a reactive twist between the upper node 1004 or platform 1010 and the base 1012. As illustrated, the reactive twist angles 1002 are measured as angles about the axis A₁₀₀₀ and between (i) a vertical plane P₁₀₀₀ extending through a given lower node 1004 of the base 1012 and the axis A₁₀₀₀ and (ii) the upper distal end 1006 of the strut 1002 associated with the given lower node 1004. FIG. 14C illustrates the support structure 1000 in a second reactive state, whereby a second compressive load L₂ is applied to the upper node 1004. Under the second compressive load L₂, the upper node 1004 is displaced by a second distance D₂ and the reactive twist angles β₁₀₀₂ increase further. When the compressive load L₂ is reduced or removed, the resiliency of the materials forming the struts 1002 cause the support structure 1000 to return to the resting height H₁₀₀₀. Thus, the support structure 1000 is configured to cycle between the compressed and uncompressed state in connection with each gait cycle.

The support structure 1000 are configured to provide a structural cushioning component, whereby the cushioning characteristics are defined by the structural properties of the struts 1002. As shown in FIGS. 14D and 14E, this mechanical response provides favorable performance characteristics compared to conventional foam cushioning elements that rely solely on material compression properties. For example, FIG. 14D illustrates representative testing data showing that the load L applied to an example support structure 1000 remains within a limited range (e.g., approximately 60-80 Newtons) across a wide displacement range (e.g., 4-10 mm), while foam cushioning elements experience continuously increasing loads (e.g., from approximately 35 Newtons up to approximately 100 Newtons) across the same range of displacement.

Referring now to FIGS. 15A-15D, another example of a tunable characteristic for the support structure 1000 is illustrated. In the illustrated examples, three variations of support structure 1000a-1000c are provided having different strut angles θ_1000a-θ_1000c relative to a plane defined by the base 1012a. Changing the strut angle θ₁₀₀₀ directly corresponds to the proportion of the compressive load L that is transferred along each strut as (a) an axial load (i.e., along the length) or (b) a bending load. In other words, decreasing the strut angle θ₁₀₀₀ causes a larger proportion of the compressive load L to be applied to the strut 1002 as a bending load, thereby reducing the magnitude of the compressive load L required to induce bending or displacement. Thus, as shown in the graph of FIG. 16D, modifying the strut angles θ₁₀₀₀ of the support structure 1000 changes a load-to-displacement ratio for the support structure 1000. For example, at a given displacement, a support structure 1000a with struts 1002 oriented at 450 strut angles θ_1000a experiences a greater load than a support structure 1000c with struts 1002 oriented at 35° strut angles θ_1000c. Accordingly, a desired strut angle may be selected based on the desired cushioning characteristics for a particular region of the midsole 102.

Referring now to FIGS. 16A-16D, another example of a tunable characteristic for the support structure 1000 is illustrated. In the illustrated examples, three variations of support structure 1000d-1000f are provided having different strut thicknesses T_1002d-T_1002f. In this example, each of the struts 1002d-1002f includes a substantially cylindrical shape such that the thicknesses T_1002a-Ti_1002c correspond to a diameter. However, as discussed below, different strut profiles may be used, such as polygonal or irregular profiles. As shown in the graph of FIG. 17D, modifying the strut thicknesses T₁₀₀₂ of the support structure 1000 changes a load-to-displacement ratio for the support structure 1000. Thus, a support structure 1000d with struts 1002 having a 5 mm diameter has a higher load-to-displacement ratio than a support structure 1000f with struts 1002 having a 3 mm diameter. Accordingly, a desired strut thickness may be selected based on the desired cushioning characteristics for a particular region of the midsole 102.

Referring now to FIGS. 17A-17E, another example of a tunable characteristic for the support structure 1000 is illustrated. In the illustrated examples, four variations of support structure 1000g-1000j are provided having different pre-twist angles Φ₁₀₀₂. The pre-twist angle (1002 is defined as an angle of rotation of the platform 1010 (the upper node 1004) relative to the base 1012 about a vertical axis A₁₀₀₀ of the support structure 1000. For example, the support structure 1000g shown in FIG. 17A has a pre-twist angle Φ_1002g of 0°, whereby each of the struts 1002 extends straight from the base 1012g to the platform 1010g. By comparison, the support structure 1000h-1000i have respective pre-twist angles Φ_1002h-Φ_1002i of 5°, 60°, and 95°. The pre-twist angles Φ_1002h-Φ_1002i are measured as angles about the axis A₁₀₀₀ and between (i) a vertical plane P₁₀₀₀ extending through a given lower node 1004 of the base 1012 and the axis A₁₀₀₀ and (ii) the upper distal end 1006 of the respective strut 1002 associated with the given lower node 1004. As shown in the graph of FIG. 17D, modifying the pre-twist angle D₁₀₀₂ of the support structure 1000 changes a ratio of load-to-displacement for the support structure 1000. Thus, a support structure 1000g with a pre-twist angle D_1002g of 0° has a higher load-to-displacement ratio than a support structure 1000j with a pre-twist angle D_1002j of 95°. Accordingly, a desired pre-twist angle D₁₀₀₂ may be selected based on the desired cushioning characteristics for a particular region of the midsole 102.

FIGS. 18A and 18B show examples of constructions for the truss structures 1000. While the illustrated examples represent cross sections of cylindrical struts 1002, the construction principals described here would also apply to other elements of the truss structure 1000 (e.g., upper and lower chords of the platform and base) and to elements having non-cylindrical profiles (e.g., polygonal or irregular). With particular reference to FIG. 18A, the strut 1002 is formed of a foamed material and includes an outer sheath 1016a having a first thickness T_1016a and an inner core 1018a enclosed within the sheath 1016a and having a second thickness T_1016a. FIG. 18B provides another example construction for the strut 1002, where the strut 1002 is provided with a sheath 1016b having a thickness T_1016b that is greater than the thickness T_1016a of the sheath 1016a of the example of FIG. 18A and the core 1018b having a thickness T_1018b that is less than the thickness T_1018a of the core 1018a of FIG. 18A. FIGS. 18A and 18B are merely provided as examples of how the relative thicknesses of the sheaths 1016a, 1016b and cores 1018a, 1018b can be modified to tune the cushioning properties of the struts 1002. As discussed in the Materials section provided below, the sheath 1016a and the core 1018a may include the same or different material components, but have different material properties. For example, the sheath 1016a may have a different density than the core 1018a. Specifically, the sheath 1016a may have a greater density than the core 1018a, whereby the sheath 1016a provides structural integrity to the strut 1002 and the core provides a lightweight filler material.

While these examples provide representative illustrations of various combinations of tunable characteristics for the truss structures 1000, other examples of the truss structures may include any combination of strut angles θ₁₀₀₀, thicknesses T₁₀₀₂, and pre-twist angles Φ₁₀₀₂. Additionally, respective struts 1002 of each truss structure 1000 may be individually configured with any of these tunable characteristics. For example, a first strut 1002 of a truss structure 1000 may include a first combination of tunable characteristics and a second strut 1002 of the same truss structure 1000 may include a second combination of tunable characteristics.

The support structures 202, the struts 204 (e.g., the first strut, the second strut, etc.), and/or the composite structures (e.g., sheath 1016 and core 1018 shown in FIGS. 22A and 22B) comprising these struts 204 may be made using polymeric materials (e.g., a polymeric first sheath material, a polymeric first core material, a polymeric second sheath material, a polymeric second core material, a polymeric filler material, etc.). Accordingly, the polymeric materials described herein are understood to comprise, consist essentially of, or consist of one or more polymers. All the one or more polymers present in a polymeric material constitute the polymeric component of the polymeric material. Similarly, when a polymeric material comprises one or more non-polymer additives, all of the non-polymeric additives present in the polymeric material constitute the non-polymeric component of the polymeric material. The one or more polymers of a polymeric material may comprise, consist essentially of, or consist of thermoplastics. A thermoplastic is a polymer that is a solid when cooled, and which can be repeatedly softened and melted on heating. The one or more polymers of a polymeric material may comprise, consist essentially of, or consist of elastomers. An elastomer may be defined as a polymer having an elongation at break greater than 100 percent, or greater than 200 percent, or greater than 400 percent, as determined using ASTM D-412-98 at 25 degrees Celsius. An elastomeric material may be defined as a composition having an elongation at break greater than 100 percent, or greater than 200 percent, or greater than 400 percent, as determined using ASTM D-412-98 at 25 degrees Celsius.

The one or more polymers of a polymeric material may include one or more of a variety of polymers, including homopolymers and copolymers and combinations of homopolymers and copolymers. The one or more polymers may comprise, consist essentially of, or consist of a polymer chosen from a polyurethane, a polyurea, a polyester, a polyether, a polyamide, a polyimide, a polyolefin, a polystyrene, a polysiloxane, a polycarbonate, a polyacetate, and any combination thereof, including homopolymers and copolymers thereof. The one or more polymers may comprise, consist essentially of, or consist of a polymer chosen from a polyurethane, a polyester, a polyamide, a polystyrene, a polyolefin, and any combination thereof, including homopolymers and copolymers thereof. The one or more polymers may comprise, consist essentially of, or consist of polyurethanes. Examples of polyurethanes include thermoplastic polyurethanes (TPUs), such as polyester-polyurethane copolymers and polyether-polyurethane copolymers, including thermoplastic elastomeric polyurethanes. The one or more polymers may comprise, consist essentially of, or consist of polyesters. Examples polyesters include polyester homopolymers such as polyethylene terephthalate (PET), and polyester copolymers such as polyetheresters, including thermoplastic polyester copolymers. The one or more polymers may comprise, consist essentially of, or consist of polyamides. Examples of polyamide homopolymers include thermoplastic polyamide homopolymers such as Nylon-6, Nylon-6,6, and Nylon-11. Examples of polyamide copolymers include thermoplastic polyamide copolymers such as thermoplastic elastomeric polyamide block copolymers, for example polyether block amide (PEBA) thermoplastic elastomers. The one or more polymers may comprise, consist essentially of, or consist of polystyrenes. Examples of polystyrenes include thermoplastic polystyrene homopolymers such as thermoplastic polystyrene homopolymer elastomers. Examples of polystyrenes also include thermoplastic polystyrene copolymers such as thermoplastic polystyrene copolymer elastomers, for example, a styrene-butadiene-styrene (SBS) copolymer or a styrene-ethylene-butadiene-styrene (SEBS) copolymer. The one or more polymers may comprise, consist essentially of, or consist of polyolefins. Examples of polyolefins include thermoplastic polyolefin elastomers, including thermoplastic polyolefin homopolymer elastomers and thermoplastic polyolefin copolymer elastomers. Examples of polyolefin homopolymers include polyethylene and polypropylene. Examples of polyolefin copolymers include polyethylene-polypropylene copolymers, as well as ethylene-vinyl acetate copolymers (EVA) and ethylene-vinyl alcohol (EVOH) copolymers.

The polymeric material may comprise from about 5 weight percent to about 100 weight percent of the polymeric component based on a total weight of the polymeric material. The polymeric component can comprise from about 15 weight percent to about 100 weight percent, from about 30 weight percent to about 100 weight percent, from about 50 weight percent to about 100 weight percent, or from about 70 weight percent to about 100 weight percent of the polymeric material. When the polymeric material comprises a non-polymeric component, the non-polymeric component may comprise from about 1 weight percent to about 20 weight percent, or from about 1 weight percent to about 10 weight percent, or from about 1 weight percent to about 5 weight percent based on a total weight of the polymeric material. As used herein, the terms “consist essentially of”, “consists essentially of” and “consisting essentially of” refer to compositions which consist of less than 1 weight percent of materials other than those recited, based on a total weight of the composition. For example, “a polymeric material consisting essentially of thermoplastics” is understood to be a polymeric material which included less than 1 weight percent of non-thermoplastic polymers and non-polymeric materials; while “a polymeric material comprising a polymeric component consisting essentially of thermoplastics” is understood to include a polymeric component in which less than 1 weight percent of the polymers present are non-thermoplastic polymers, but this polymeric material may include more than 1 weight percent of non-polymeric materials.

In some aspects, the polymeric material may be a material which polymerizes or crosslinks or both polymerizes and crosslinks during the process of forming the support or during the process of forming the sole structure. The polymerization or crosslinking may be initiated by including a chemical polymerization or crosslinking initiator in the polymeric material (e.g., a chemical which initiates polymerization or crosslinking reactions within the polymeric material when it is exposed to thermal energy, UV light, or another form of actinic radiation), or the polymerization or crosslinking may be initiated by mixing together two compositions which react to produce polymerization or crosslinking reactions, or by exposing a polymeric material to a form of actinic radiation in sufficient quantity to polymerize pre-polymers or oligomers present in the exposed material, or to crosslink polymers present in the exposed polymeric material. In aspects where the material polymerizes, the polymeric material may initially comprise one or more pre-polymers or oligomers which react and polymerize during the manufacturing process, resulting in a support or sole structure comprising the reacted polymeric material. In aspects where the material crosslinks, the polymeric material may initially comprise one or more crosslinkable polymers which react with crosslinking agents or crosslinking energy and become crosslinked polymers during the manufacturing process, resulting in a support or sole structure comprising a crosslinked polymeric material. In some aspect, the resulting reacted polymeric material is a thermoset material. Similarly, in some aspects, the initial polymeric material may be a thermosetting thermoplastic material (e.g., a polymeric material comprising one or more thermoplastics and a crosslinking agent before it is thermally processed), and the resulting crosslinked polymeric material is a thermoset material (e.g., after the crosslinking agent reacts with the thermoplastics and crosslinks them, and the resulting thermoset material is solidified). One example of this is a thermosettable molten thermoplastic material comprising a thermally-activated crosslinking agent and a foaming agent, where the thermally-activated crosslinking agent is activated during a foaming process, resulting in a thermoset foam material.

Optionally, the polymeric material may comprise one or more additives. Examples of additives include fillers, polymerization initiators, crosslinking agents, UV light absorbers, anti-oxidants, processing aids such as lubricants and plasticizers, and colorants, such as pigments and dyes. Fillers may include non-polymeric fillers such as silica, clay, and titanium dioxide. Fillers may include polymeric fillers such as polymeric fibers and finely-ground polymeric powders, including ground thermoset rubber. Colorants such as naturally-occurring and synthetic pigments and dyes may be used. The polymeric material may comprise one or more additives at a concentration of from about 0.1 weight percent to about 20 weight percent, or from about 0.2 weight percent to about 10 weight percent, or from about 0.5 weight percent to about 5 weight percent, based on a total weight of the polymeric material.

The polymeric material may comprise one or more foaming agents. As understood in the art, foaming agents are substances that react, decompose or vaporize to produce quantities of gases or vapors. A chemical foaming agent is a compound which, when reacted with a second chemical or on decomposition, release a gas. Examples of chemical foaming agents include sodium bicarbonate, ammonium carbonate, ammonium bicarbonate, calcium azide, azodicarbonamide, hydrazocarbonamide, benzenesulfonyl hydrazide, dinitrosopentamethylene tetramine, toluenesulfonyl hydrazide, p,p′-oxybis(benzenesulfonylhydrazide), azobisisobutyronitrile, barium azodicarboxylate, and any combination thereof. A physical blowing agent is a compound which phase transitions from a solid, liquid or supercritical fluid to a gas when the temperature, pressure, or temperature and pressure are changed. Physical blowing agents include low-boiling-point hydrocarbons, including hydrocarbons such as isobutene and pentane, and partially halogenated hydrocarbons such as partially halogenated fluorochlorohydrocarbons, inert gasses, and supercritical fluids. In some aspects, the foaming agent is a supercritical fluid, such as supercritical carbon dioxide (CO2) or supercritical nitrogen (N2). The one or more foaming agents may include a chemical foaming agent and a physical foaming agent.

When a foaming agent is used, prior to the foaming step, the foaming agent may be present in the polymeric material in an amount effective to foam the polymeric material into a multicellular foam during the manufacturing process. The amount of foaming agent may be measured as the concentration of foaming agent by weight in the polymeric material prior to the foaming step. An amount of blowing agent is considered effective when the foaming process results in at least a 10 percent increase in the volume of the polymeric material, or at least a 20 percent increase in the volume of the polymeric material, or in at least a 30 percent increase in the volume of the polymeric material. The polymeric material may comprise from about 1 percent to about 30 percent by weight, or from about 1 percent to about 20 percent by weight, or from about 1 percent to about 10 percent by weight of the foaming agent based on a total weight of the polymeric material. The polymeric material may comprise a concentration of the foaming agent sufficient to expand the polymeric material by at least 100 percent by volume, or by 100 percent to 900 percent by volume, or by 200 percent to 500 percent by volume, or by 300 percent to 400 percent by volume, based on an initial volume of the polymeric material prior to foaming.

The foregoing description has been provided for purposes of illustration and description. It is not intended to be exhaustive or to limit the disclosure. Individual elements or features of a particular configuration are generally not limited to that particular configuration, but, where applicable, are interchangeable and can be used in a selected configuration, even if not specifically shown or described. The same may also be varied in many ways. Such variations are not to be regarded as a departure from the disclosure, and all such modifications are intended to be included within the scope of the disclosure.