Patent Publication Number: US-11659890-B2

Title: Flexible fluid-filled chamber with tensile member

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. patent application Ser. No. 15/259,802, filed Sep. 8, 2016, the disclosure of which is hereby incorporated by reference in its entirety. 
    
    
     FIELD 
     The present invention relates generally to fluid-filled chambers for use in the sole structure of an article of footwear. 
     BACKGROUND 
     Conventional articles of athletic footwear include two primary elements, an upper and a sole structure. The upper provides a covering for the foot that comfortably receives and securely positions the foot with respect to the sole structure. The sole structure may include fluid-filled chambers to provide cushioning and stability. The sole structure is secured to a lower portion of the upper and is generally positioned between the foot and the ground. In addition to attenuating ground reaction forces (that is, providing cushioning and stabilizing the foot during vertical and horizontal loading) during walking, running, and other ambulatory activities, the sole structure may influence foot motions (for example, by resisting pronation), impart stability, and provide traction. Accordingly, the upper and the sole structure operate cooperatively to provide a comfortable structure that is suited for a wide variety of athletic activities. 
     BRIEF SUMMARY 
     In one aspect, the present disclosure is directed to an article of footwear may have an upper and a sole structure secured to the upper. The sole structure may include a chamber for receiving a pressurized fluid, the chamber having a first chamber barrier layer and a second chamber barrier layer bonded to the first chamber barrier layer about peripheral portions of the first chamber barrier layer and the second chamber barrier layer to define an interior void between the first chamber barrier layer and the second chamber barrier layer. In addition, the chamber may include a tensile member extending between the first chamber barrier layer and the second chamber barrier layer, the tensile member including a first tensile member layer bonded to the first chamber barrier layer, a second tensile member layer bonded to the second chamber barrier layer, and a plurality of tethers connecting the first tensile member layer to the second tensile member layer. The second tensile member layer may include a first section and a second section separate from the first section. A portion of the second chamber barrier layer may extend toward the first tensile member layer between the first section and the second section of the second tensile member layer, the portion of the second chamber barrier layer that extends toward the first tensile member layer being joined to the first tensile member layer. 
     In another aspect, the present disclosure is directed to an article of footwear may have an upper and a sole structure secured to the upper. The sole structure may include a chamber for receiving a pressurized fluid, the chamber having a top barrier layer and a bottom barrier layer bonded to the top barrier layer about peripheral portions of the top barrier layer and the bottom barrier layer to define an interior void between the top barrier layer and the bottom barrier layer. The chamber may also include a tensile member extending between the top barrier layer and the bottom barrier layer, the tensile member including a first tensile member layer, the first tensile member layer having an upper surface and a lower surface, the upper surface of the first tensile member layer being bonded to a lower surface of the top barrier layer; a second tensile member layer having a lower surface bonded to the bottom barrier layer; and a plurality of tethers connecting the first tensile member layer to the second tensile member layer. The tensile member may include a first tensile member section and a second tensile member section, the first tensile member layer extending continuously between the first tensile member section and the second tensile member section. The second tensile member layer is discontinuous and includes a first tensile member layer section and a second tensile member layer section separated from the first tensile member layer section by a gap. In addition, a portion of the bottom barrier layer extends upward in the gap between the first tensile member layer section and the second tensile member layer section. 
     In another aspect, the present disclosure is directed to a die set for forming a chamber. The die set may include a first die having a substantially planar first die surface and a second die having a substantially planar second die surface. The first die and the second die may include peripheral portions configured to compress and bond chamber barrier layers to one another when the first die and the second die are pressed against one another. The second die may have an elongated projection extending from the substantially planar second die surface. Also, the elongated projection may be configured to bond portions of the chamber to one another when the first die and the second die are pressed against one another. 
     In another aspect, the present disclosure is directed to a method of making an article of footwear having an upper and a sole structure secured to the upper. The method may include forming a chamber for receiving a pressurized fluid by assembling a stacked arrangement of chamber components. The stacked arrangement of chamber components may include a first chamber barrier layer, a second chamber barrier layer, and a tensile member extending between the first chamber barrier layer and the second chamber barrier layer. The tensile member may include a first tensile member layer, a second tensile member layer, and a plurality of tethers connecting the first tensile member layer to the second tensile member layer. The second tensile member layer may include a first section and a second section separate from the first section. The method may also include bonding the first chamber barrier layer to the second chamber barrier layer to form peripheral portions of the chamber and to define an interior void between the first chamber barrier layer and the second chamber barrier layer. Further, the method may include extending a portion of the second chamber barrier layer toward the first tensile member layer between the first section of the second tensile member layer and the second section of the second tensile member layer, pressing the portion of the second chamber barrier layer against the first tensile member layer. Additionally, the method may include joining the portion of the second chamber barrier layer to the first tensile member layer between the first section of the second tensile member layer and the second section of the second tensile member layer, bonding the first tensile member layer to the first chamber barrier layer, and bonding the second tensile member layer to the second chamber barrier layer. Also, the method may include inflating the chamber with a pressurized fluid, incorporating the chamber into the sole structure, and attaching the sole structure to the upper. 
     In another aspect, the present disclosure is directed to a method of making a sole structure for an article of footwear, including forming a chamber for receiving a pressurized fluid. Forming the chamber may include assembling a stacked arrangement of chamber components. The stacked arrangement of chamber components may include a first chamber barrier layer, a second chamber barrier layer, and a tensile member extending between the first chamber barrier layer and the second chamber barrier layer. The tensile member may include a first tensile member layer, a second tensile member layer, and a plurality of tethers connecting the first tensile member layer to the second tensile member layer, wherein the second tensile member layer is discontinuous such that a first section of the second tensile member layer is separated from a second section of the second tensile member layer by a gap. The method may include bonding the first chamber barrier layer to the second chamber barrier layer to form peripheral portions of the chamber and to define an interior void between the first chamber barrier layer and the second chamber barrier layer. The method may also include extending a portion of the second chamber barrier layer toward the first tensile member layer in the gap between the first section of the second tensile member layer and the second section of the second tensile member layer, pressing the portion of the second chamber barrier layer against the first tensile member layer. In addition, the method may include joining the portion of the second chamber barrier layer to the first tensile member layer between the first section of the second tensile member layer and the second section of the second tensile member layer. The method may further include bonding the first tensile member layer to the first chamber barrier layer, bonding the second tensile member layer to the second chamber barrier layer, and inflating the chamber with a pressurized fluid. 
     In another aspect, the present disclosure is directed to a method of making a sole structure for an article of footwear, including forming a chamber for receiving a pressurized fluid. Forming the chamber may include assembling a stacked arrangement of chamber components. The stacked arrangement of chamber components may include a first chamber barrier layer, a second chamber barrier layer, and a tensile member extending between the first chamber barrier layer and the second chamber barrier layer, the tensile member including a first tensile member layer, a second tensile member layer, and a plurality of tethers connecting the first tensile member layer to the second tensile member layer, wherein the second tensile member layer is discontinuous such that a first section of the second tensile member layer is separated from a second section of the second tensile member layer by a gap. The method may include bonding the first chamber barrier layer to the second chamber barrier layer to form peripheral portions of the chamber and to define an interior void between the first chamber barrier layer and the second chamber barrier layer. Also, the method may include extending a portion of the second chamber barrier layer toward the first tensile member layer in the gap between the first section of the second tensile member layer and the second section of the second tensile member layer, pressing the portion of the second chamber barrier layer against the first tensile member layer. Further, the method may include joining the portion of the second chamber barrier layer to the first tensile member layer and inflating the chamber with a pressurized fluid. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention can be better understood with reference to the following drawings and description. The components in the figures are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the invention. Moreover, in the figures, like reference numerals designate corresponding parts throughout the different views. 
         FIG.  1    shows an article of footwear according to an exemplary embodiment. 
         FIG.  2    shows an exploded view of an exemplary sole structure for an article of footwear. 
         FIG.  3    shows a cross-sectional view of a portion of the sole structure taken at section line  3 - 3  in  FIG.  2   . 
         FIG.  4    shows an exemplary article of footwear having a sole structure including a fluid-filled chamber. 
         FIG.  5    shows a perspective view of the chamber shown in  FIG.  4   . 
         FIG.  6    shows a cross-sectional view of a portion of the chamber taken at section line  6 - 6  in  FIG.  5   . 
         FIG.  7    shows an exploded view of chamber components, and a die set for joining portions of the chamber components to one another. 
         FIG.  8    shows a first process of a manufacturing method of forming the chamber shown in  FIG.  6   . 
         FIG.  9    shows a second process of a manufacturing method of forming the chamber shown in  FIG.  6   . 
         FIG.  10    shows a further stage of the second process shown in  FIG.  9   . 
         FIG.  11    shows a further step of the method of forming the chamber shown in  FIG.  6   . 
         FIG.  12    shows an assembled, cross-sectional view of the chamber formed in the method shown in  FIGS.  7 - 11   . 
         FIG.  13    shows an assembled, cross-sectional view of another exemplary fluid-filled chamber. 
         FIG.  14    shows another die configured to perform a portion of a method of forming a chamber. 
         FIG.  15    shows the die of  FIG.  14    with a chamber barrier layer drawn against it using vacuum pressure. 
         FIG.  16    shows an assembled, cross-sectional view of the chamber formed in the method shown in  FIG.  15   . 
         FIG.  17    shows an assembled, cross-sectional view of another exemplary fluid-filled chamber. 
         FIG.  18    shows an assembled, cross-sectional view of another exemplary fluid-filled chamber. 
         FIG.  19    shows the chamber of  FIG.  18    in an articulated condition. 
     
    
    
     DESCRIPTION 
     As previously discussed, articles of athletic footwear commonly include two primary elements, an upper and a sole structure. The upper is often formed from a plurality of material elements (for example, textiles, polymer sheets, foam layers, leather, synthetic leather, and other materials) that are stitched or adhesively bonded together to define a void on the interior of the footwear for comfortably and securely receiving a foot. More particularly, the upper forms a structure that extends over instep and toe areas of the foot, along medial and lateral sides of the foot, and around a heel area of the foot. The upper may also incorporate a lacing system to adjust fit of the footwear, as well as permit entry and removal of the foot from the void within the upper. In addition, the upper may include a tongue that extends under the lacing system to enhance adjustability and comfort of the footwear, and the upper may incorporate a heel counter. 
     The sole structure generally incorporates multiple layers, including, for example, a sockliner, a midsole, and a ground-engaging outer member. The sockliner is a thin, compressible member located within the upper and adjacent to a plantar (that is, lower) surface of the foot to enhance footwear comfort. The midsole is secured to a lower surface of the upper and forms a middle layer of the sole structure. Many midsole configurations are primarily formed from a resilient polymer foam material, such as polyurethane (PU) or ethyl vinyl acetate (EVA), that extends throughout the length and width of the footwear. The midsole may also incorporate plates, moderators, and/or other elements that further attenuate forces, influence the motions of the foot, and/or impart stability, for example. The ground-engaging outer member may be fashioned from a durable and wear-resistant material (for example, rubber) that includes texturing to improve traction. 
     Further, the sole structure may include fluid-filled chambers to provide cushioning and stability. Upon inflation, such chambers experience pressure that is evenly distributed to all portions of the inner surface of the bladder material from which the chamber is formed. Accordingly, the tendency is for chambers, when inflated, to take on an outwardly rounded shape. For use as cushioning members in footwear, however, it is desirable to provide the chambers with a relatively flat form, to serve as a platform for receiving the sole of a foot of a wearer. Thus, to limit the expansion of the top and bottom portions of the chamber upon inflation, sole structures have been developed with chambers having one or more tensile structures that link the top portion of the chamber to the bottom portion of the chamber in order to maintain the chambers in a substantially planar configuration. However, such tensile members may provide increased stiffness to the chambers. Accordingly, there is a need for chamber configurations that provide tensile member-equipped fluid-filled chambers with increased flexibility. 
     The present disclosure is generally directed to fluid-filled chamber configurations including tensile members including a top sheet, a bottom sheet, and a plurality of tethers extending between the top sheet and the bottom sheet. In order to provide flexibility to the chamber, the top or bottom tensile member sheet may be discontinuous and a portion of the barrier layer of the chamber may be fixedly attached to the tensile member sheet on the opposite side of the chamber. This configuration may form the chamber with a reduced thickness in the area of the discontinuity in the tensile member sheet. Due to the reduced thickness, the area of the chamber having the reduced thickness may be more flexible than other portions of the chamber. For example, the reduced thickness may form a flex groove. Such flex grooves may be selectively located at various portions of the chamber corresponding with portions of the article of footwear sole structure that are desired to have greater flexibility, such as the portion of the forefoot region corresponding with the ball of the foot. 
     The following discussion and accompanying figures disclose a sole structure for an article of footwear. Concepts associated with the footwear disclosed herein may be applied to a variety of athletic footwear types, including running shoes, basketball shoes, cross-training shoes, cricket shoes, golf shoes, soccer shoes, baseball shoes, cycling shoes, football shoes, golf shoes, tennis shoes, and walking shoes, for example. Accordingly, the concepts disclosed herein apply to a wide variety of footwear types. 
     For consistency and convenience, directional adjectives are employed throughout this detailed description corresponding to the illustrated embodiments. The term “longitudinal,” as used throughout this detailed description and in the claims, refers to a direction extending a length of a sole structure, i.e., extending from a forefoot portion to a heel portion of the sole. The term “forward” is used to refer to the general direction in which the toes of a foot point, and the term “rearward” is used to refer to the opposite direction, i.e., the direction in which the heel of the foot is facing. 
     The term “lateral direction,” as used throughout this detailed description and in the claims, refers to a side-to-side direction extending in the direction of the width of a sole. In other words, the lateral direction may extend between a medial side and a lateral side of an article of footwear, with the lateral side of the article of footwear being the surface that faces away from the other foot, and the medial side being the surface that faces toward the other foot. 
     The term “lateral axis,” as used throughout this detailed description and in the claims, refers to an axis oriented in a lateral direction. 
     The term “horizontal,” as used throughout this detailed description and in the claims, refers to any direction substantially parallel with the ground, including the longitudinal direction, the lateral direction, and all directions in between. Similarly, the term “side,” as used in this specification and in the claims, refers to any portion of a component facing generally in a lateral, medial, forward, and/or rearward direction, as opposed to an upward or downward direction. 
     The term “vertical,” as used throughout this detailed description and in the claims, refers to a direction generally perpendicular to both the lateral and longitudinal directions. For example, in cases where a sole is planted flat on a ground surface, the vertical direction may extend from the ground surface upward. It will be understood that each of these directional adjectives may be applied to individual components of a sole. The term “upward” refers to the vertical direction heading away from a ground surface, while the term “downward” refers to the vertical direction heading towards the ground surface. Similarly, the terms “top,” “upper,” and other similar terms refer to the portion of an object substantially furthest from the ground in a vertical direction, and the terms “bottom,” “lower,” and other similar terms refer to the portion of an object substantially closest to the ground in a vertical direction. 
     For purposes of this disclosure, the foregoing directional terms, when used in reference to an article of footwear, shall refer to the article of footwear in an upright position, with the sole facing groundward as it would be positioned when worn by a wearer standing on a substantially level surface. 
     In addition, for purposes of this disclosure, the term “fixedly attached” shall refer to two components joined in a manner such that the components may not be readily separated (for example, without destroying one or both of the components). Exemplary modalities of fixed attachment may include joining with permanent adhesive, rivets, stitches, nails, staples, welding or other thermal bonding, chemical or molecular bonding, and/or other joining techniques. In addition, two components may be “fixedly attached” by virtue of being integrally formed, for example, in a molding process. 
     As utilized herein, the term “welding” or variants thereof is defined as a securing technique between two elements that involves a softening or melting of a polymer material within at least one of the elements such that the materials of the elements are secured to each other when cooled. When exposed to sufficient heat, one or more of the polymer materials of chamber components transition from a solid state to either a softened state or a liquid state, particularly when a thermoplastic polymer material is utilized. When sufficiently cooled, the polymer materials then transition back from the softened state or the liquid state to the solid state. Based upon these properties of polymer materials, welding processes may be utilized to form a bond or weld between air chamber components. Thus, the term “weld” or variants thereof is defined as the bond, link, or structure that joins two elements through a process that involves a softening or melting of a polymer material within at least one of the elements such that the materials of the elements are secured to each other when cooled. As examples, welding may involve (a) the melting or softening of two elements that include polymer materials such that the polymer materials from each element intermingle with each other (e.g., diffuse across a boundary layer between the polymer materials) and are secured together when cooled and (b) the melting or softening of a polymer material in a first element such that the polymer material extends into or infiltrates the structure of a second element (e.g., infiltrates crevices or cavities formed in the second element or extends around or bonds with filaments or fibers in the second element) to secure the two elements together when cooled. Welding may occur when only one element includes a polymer material or when both elements include polymer materials. Additionally, welding does not generally involve the use of stitching or adhesives, but involves directly bonding elements to each other with heat. In some situations, however, adhesives may be utilized to supplement the weld or the joining of the elements through welding. 
       FIG.  1    depicts an embodiment of an article of footwear  100 , which may include a sole structure  105  and an upper  110  secured to sole structure  105 . As shown in  FIG.  1    for reference purposes, footwear  100  may be divided into three general regions, including a forefoot region  130 , a midfoot region  135 , and a heel region  140 . Forefoot region  130  generally includes portions of footwear  100  corresponding with the toes and the joints connecting the metatarsals with the phalanges. Midfoot region  135  generally includes portions of footwear  100  corresponding with an arch area of the foot. Heel region  140  generally corresponds with rear portions of the foot, including the calcaneus bone. Forefoot region  130 , midfoot region  135 , and heel region  140  are not intended to demarcate precise areas of footwear  100 . Rather, forefoot region  130 , midfoot region  135 , and heel region  140  are intended to represent general relative areas of footwear  100  to aid in the following discussion. 
     Since sole structure  105  and upper  110  both span substantially the entire length of footwear  100 , the terms forefoot region  130 , midfoot region  135 , and heel region  140  apply not only to footwear  100  in general, but also to sole structure  105  and upper  110 , as well as the individual elements of sole structure  105  and upper  110 . Footwear  100  may be formed of any suitable materials. In some configurations, the disclosed footwear  10  may employ one or more materials disclosed in Lyden et al., U.S. Pat. No. 5,709,954, issued Jan. 20, 1998, the entire disclosure of which is incorporated herein by reference. 
     Upper  110  may include one or more material elements (formed, for example, of textiles, foam, leather, and/or synthetic leather), which may be stitched, adhesively bonded, molded, or otherwise formed to define an interior void configured to receive a foot. The material elements may be selected and arranged to selectively impart properties such as durability, air-permeability, wear-resistance, flexibility, and comfort. Upper  110  may alternatively implement any of a variety of other configurations, materials, and/or closure mechanisms. 
     Sole structure  105  may have a configuration that extends between upper  110  and the ground and may be secured to upper  110  in any suitable manner. For example, sole structure  105  may be secured to upper  110  by adhesive attachment, stitching, welding, or any other suitable method. Sole structure  105  may include provisions for attenuating ground reaction forces (that is, cushioning and stabilizing the foot during vertical and horizontal loading). In addition, sole structure  105  may be configured to provide traction, impart stability, and/or limit various foot motions, such as pronation, supination, and/or other motions. 
     The configuration of sole structure  105  may vary significantly according to one or more types of ground surfaces on which sole structure  105  may be used. For example, the disclosed concepts may be applicable to footwear configured for use on indoor surfaces and/or outdoor surfaces. The configuration of sole structure  105  may vary based on the properties and conditions of the surfaces on which footwear  100  is anticipated to be used. For example, sole structure  105  may vary depending on whether the surface is harder or softer. In addition, sole structure  105  may be tailored for use in wet or dry conditions. 
     Sole structure  105  may include multiple components, which may individually and/or collectively provide footwear  100  with a number of attributes, such as support, rigidity, flexibility, stability, cushioning, comfort, reduced weight, traction, and/or other attributes. As shown in  FIG.  1   , sole structure  105  may include a ground-contacting outer member  120 . In addition, in some embodiments, sole structure  105  may also include a midsole  115  disposed between outer member  120  and upper  110 . 
     Outer member  120  may include an outer surface  125  exposed to the ground. Outer member  120  may include various features configured to provide traction. For example, in some embodiments, outer surface  125  may include a patterned tread, as shown in  FIG.  1   . In some embodiments, outer member  120  may include one or more ground-engaging cleat members extending from outer surface  125 . 
     Outer member  120  may be formed of suitable materials for achieving the desired performance attributes. For example, outer member  120  may be formed of any suitable polymer, composite, and/or metal alloy materials. Exemplary such materials may include thermoplastic and thermoset polyurethane, polyester, nylon, polyether block amide, alloys of polyurethane and acrylonitrile butadiene styrene, carbon fiber, poly-paraphenylene terephthalamide (para-aramid fibers, e.g., Kevlar®), titanium alloys, and/or aluminum alloys. In some embodiments, outer member  120  may be fashioned from a durable and wear-resistant material (for example, rubber). Other suitable materials, including future-developed materials, will be recognized by those having skill in the art. Materials and configurations for outer member  120  may be selected according to the type of activity for which footwear  100  is configured. 
     Midsole  115  may have any suitable configuration and may provide cushioning and stability. For example, in some embodiments, midsole  115  may be formed of a compressible material, such as a resilient polymer foam material, examples of which may include polyurethane (PU) or ethyl vinyl acetate (EVA). In some embodiments, midsole  115  may extend throughout the length and width of footwear  100 . In some embodiments, midsole  115  may also incorporate incompressible plates, moderators, and/or other elements that further attenuate forces, influence the motions of the foot, and/or impart stability, for example. 
     In some embodiments, the article of footwear may be provided with features that provide flexibility to the sole of the footwear. For example, in some embodiments, one or more components of the sole structure may have a flex groove that facilitates bending of the sole. In some embodiments, the sole structure may include a plurality of flex grooves in the forefoot region of the footwear. Also, the sole structure may include layered components, including, for example, an outer member (outsole), a midsole, and a cushioning element, such as a chamber filled with a pressurized fluid. In order to facilitate bending of the layered structure, the layered components may each have corresponding flex grooves. 
       FIG.  2    illustrates a portion of footwear  100 , including sole structure  105 . As shown in  FIG.  2   , outer member  120  may have an inner surface  155  opposite outer surface  125 . Inner surface  155  may be disposed closer to a wearer&#39;s foot than outer surface  125  when footwear  100  is worn by the wearer. That is, inner surface  155  may be disposed upward of outer surface  125 . Outer member  120  may include a first flex groove portion  145  and a second flex groove portion  150 . First flex groove portion  145  may include a first elongate recess  160  in outer surface  125  of outer member  120 . Elongate recess  160  may be formed by an upward curvature in outer surface  125  of outer member  120 , which extends in an upward direction (that is, toward the wearer&#39;s foot when footwear  100  is worn by the wearer). 
     In some embodiments, outer member  120  may have a substantially consistent thickness. Due to the consistent thickness of outer member  120 , inner surface  155  of outer member  120  may also include an upward curvature, extending in an upward direction (that is, toward the wearer&#39;s foot when footwear  100  is worn by the wearer), thus forming an elongate rib  165  in first flex groove portion  145 . Accordingly, both outer surface  125  and inner surface  155  of outer member  120  may curve towards the wearer&#39;s foot when footwear  100  is worn by a wearer. 
     First flex groove portion  145  may separate a first outer member forefoot region  170  from a second outer member forefoot region  175 . In some embodiments, first flex groove  145  may form a thinner portion of outer member  120  (in a vertical direction) than other portions of outer member  120  (such as first outer member forefoot region  170  and second outer member forefoot region  175 ), in order to provide increased flexibility of outer member  120  in this area. 
     In some embodiments, first flex groove portion  145  may extend in a lateral direction. For example, footwear  100 , and therefore outer member  120 , may have a medial side  131  and a lateral side  132 . As shown in  FIG.  2   , elongate recess  160  and elongate rib  165  of first flex groove portion  145  may extend substantially from a medial edge  133  of outer member  120  to a lateral edge  134  of outer member  120 . Further, in some embodiments, first flex groove portion  145  may extend completely from medial edge  133  to lateral edge  134 , as shown in  FIG.  2   . 
     In some embodiments, outer member  110  may also include one or more additional flex groove portions, such as second flex groove portion  150 , as shown in  FIG.  2   . Second flex groove portion  150  may separate second forefoot region  175  from a third forefoot region  180 . Second flex groove portion  150  may form a thinner portion of outer member  110  than other portions of outer member  110 , in order to provide increased flexibility of outer member  110 . Second flex groove portion  150  may include a second elongate recess  185  in outer surface  125  of outer member  120 . As with first elongate recess  160 , elongate recess  185  may extend in an upward direction (that is, toward the wearer&#39;s foot when footwear  100  is worn by the wearer). Also similar to first flex groove portion  145 , second flex groove portion  150  may also include a second elongate rib  190  formed by the upward curvature of inner surface  155  of outer member  120 . 
     As shown in  FIG.  2   , midsole  115  may have a first midsole surface  200  and a second midsole surface  205  opposite first midsole surface  200 . In some embodiments, midsole  115  may include a third flex groove portion  210 . Third flex groove portion  210  may include a third elongate recess  215  in second midsole surface  205 . Third elongate recess  215  may extend in an upward direction (that is, toward a wearer&#39;s foot when footwear  100  is worn by the wearer). Third flex groove portion  210  may also include a third elongate rib  215  in first midsole surface  200 . Third elongate rib  215  may extend in an upward direction (that is, toward the wearer&#39;s foot when footwear  100  is worn by the wearer). 
     As further shown in  FIG.  2   , midsole  115  may also include a fourth flex groove portion  225 . Fourth flex groove portion  225  may include a fourth elongate recess  230  in second midsole surface  205 . Fourth elongate recess  230  may extend in an upward direction (that is, toward a wearer&#39;s foot when footwear  100  is worn by the wearer). Fourth flex groove portion  225  may also include a fourth elongate rib  235  in first midsole surface  200 . Fourth elongate rib  235  may extend in an upward direction (that is, toward the wearer&#39;s foot when footwear  100  is worn by the wearer). 
     As shown in  FIG.  2   , in some embodiments, third elongate recess  215  in second midsole surface  205  may receive first elongate rib  165  of first flex groove portion  145  of outer member  120 . Similarly, in some embodiments, fourth elongate recess  230  in second midsole surface  205  may receive second elongate rib  190  of second flex groove portion  150  of outer member  120 . Thus, first elongate rib  165  and second elongate rib  190  may be disposed in a nested relationship with third elongate recess  215  and fourth elongate recess  230 , respectively. 
     In some embodiments, the sole structure may include one or more additional components that provide cushioning. For example, in some embodiments, the sole structure may include a chamber filled with pressurized gases. In some configurations, the chamber may include elongate indentations configured to receive elongate ribs in the midsole or outsole member and to provide the chamber with flexibility. 
     As shown in  FIG.  2   , in some embodiments, sole structure  105  may include a chamber  240  for receiving a pressurized fluid. In some embodiments, chamber  240  may include a first chamber barrier layer  245  and a second chamber barrier layer  250 . As shown in  FIG.  2   , in some embodiments, first chamber barrier layer  245  may be a top barrier layer and second chamber barrier layer  250  may be a bottom barrier layer. Second chamber barrier layer  245  may be bonded to first chamber barrier layer  240  about peripheral portions of first chamber barrier layer  240  and second chamber barrier layer  245  to define an interior void between first chamber barrier layer  240  and second chamber barrier layer  245 . 
     Chamber  240  may be formed from a polymer or other bladder material that provides a sealed barrier for enclosing a fluid. As noted above, the bladder material may be transparent. A wide range of polymer materials may be utilized for chamber  240 . In selecting materials for chamber  240 , engineering properties of the material (e.g., tensile strength, stretch properties, fatigue characteristics, dynamic modulus, and loss tangent) as well as the ability of the material to prevent the diffusion of the fluid contained by chamber  240  may be considered. When formed of thermoplastic urethane, for example, the outer barrier of chamber  240  may have a thickness of approximately 1.0 millimeter, but the thickness may range from 0.25 to 2.0 millimeters or more, for example. 
     In addition to thermoplastic urethane, examples of polymer materials that may be suitable for chamber  240  include polyurethane, polyester, polyester polyurethane, and polyether polyurethane. Chamber  240  may also be formed from a material that includes alternating layers of thermoplastic polyurethane and ethylene-vinyl alcohol copolymer, as disclosed in U.S. Pat. Nos. 5,713,141 and 5,952,065 to Mitchell, et al. A variation upon this material may also be utilized, wherein a center layer is formed of ethylene-vinyl alcohol copolymer, layers adjacent to the center layer are formed of thermoplastic polyurethane, and outer layers are formed of a regrind material of thermoplastic polyurethane and ethylene-vinyl alcohol copolymer. Another suitable material for chamber  240  is a flexible microlayer membrane that includes alternating layers of a gas barrier material and an elastomeric material, as disclosed in U.S. Pat. Nos. 6,082,025 and 6,127,026 to Bonk, et al. Additional suitable materials are disclosed in U.S. Pat. Nos. 4,183,156 and 4,219,945 to Rudy. Further suitable materials include thermoplastic films containing a crystalline material, as disclosed in U.S. Pat. Nos. 4,936,029 and 5,042,176 to Rudy, and polyurethane including a polyester polyol, as disclosed in U.S. Pat. Nos. 6,013,340; 6,203,868; and 6,321,465 to Bonk, et al. The patents listed in this paragraph are incorporated herein by reference in their entirety. 
     The fluid within chamber  240  may range in pressure from zero to three-hundred-fifty kilopascals (i.e., approximately fifty-one pounds per square inch) or more. In some configurations of sole structure  105 , a suitable pressure for the fluid may be a substantially ambient pressure. That is, the pressure of the fluid may be within five kilopascals of the ambient pressure of the atmospheric air surrounding footwear  100 . The pressure of fluid within chamber  240  may be selected to provide desirable performance attributes. For example, higher pressures may provide a more responsive cushioning element, whereas lower pressures may provide more ground force attenuation (a softer cushion). The pressure of fluid within chamber  240  may be selected to work in concert with other cushioning elements of footwear  100 , such as foam members and/or an insole (not shown). In some embodiments the insole may be formed of a compressible material. 
     In some configurations, chamber  240  may be inflated with substantially pure nitrogen. Such an inflation gas promotes maintenance of the pressure within chamber  240  through diffusion pumping, whereby the deficiency of other gases (besides nitrogen), such as oxygen, within chamber  240  biases the system for inward diffusion of such gasses into chamber  240 . Further, bladder materials, such as those discussed above, may be substantially impermeable to nitrogen, thus preventing the escape of the nitrogen from chamber  240 . 
     In some configurations, relatively small amounts of other gases, such as oxygen or a mixture of gasses, such as air, may be added to the nitrogen occupying most of the volume within chamber  240 . In addition to air and nitrogen, the fluid contained by chamber  240  may include octafluoropropane or be any of the gasses disclosed in U.S. Pat. No. 4,340,626 to Rudy, such as hexafluoroethane and sulfur hexafluoride, for example. In some configurations, chamber  240  may incorporate a valve that permits the individual to adjust the pressure of the fluid. In other configurations, chamber  240  may be incorporated into a fluid system, as disclosed in U.S. Pat. No. 7,210,249 to Passke, et al., as a pump chamber or a pressure chamber. In order to pressurize chamber  240  or portions of chamber  240 , the general inflation methods disclosed in Hensley et al., U.S. Pat. No. 8,241,450, issued Aug. 14, 2012, and entitled “Method For Inflating A Fluid-Filled Chamber,” and Schindler et al., U.S. Patent Application Publication No. US 2009/0151196, published Jun. 18, 2009, entitled “Article Of Footwear Having A Sole Structure With A Fluid-Filled Chamber” may be utilized. The patents and published patent applications listed in this paragraph are incorporated herein by reference in their entirety. 
     In some embodiments, the chamber may include one or more features that limit the expansion of the top and bottom portions of the chamber upon inflation. For example, in some embodiments, the chamber may include one or more tensile structures that link the top portion of the chamber to the bottom portion of the chamber. Such tensile structures may be substantially inelastic (or may have a limited elasticity) such that, when the chamber is inflated causing the top and bottom portions of the chamber to be biased apart from one another, the tensile structures limit the distance by which the top and bottom portions may be separated during inflation. Accordingly, the tensile members may enable the bladder to retain its intended, substantially planar shape. 
     As shown in  FIG.  2   , a tensile member  255  may extend between first chamber barrier layer  245  and second chamber barrier layer  250 . Tensile member  255  may include a first tensile member layer  260  bonded to first chamber barrier layer  245 . In addition, tensile member  255  may also include a second tensile member layer  265  bonded to second chamber barrier layer  260 . Also, tensile member  255  may include a plurality of tethers  270  connecting first tensile member layer  260  to second tensile member layer  265 . The outward force of pressurized fluid within chamber  240  places tethers  270  in tension and restrains further outward movement of first tensile member layer  260  and first chamber barrier layer  245  away from second tensile member layer  265  and second chamber barrier layer  250 . 
     Tensile member  255  may have any configuration suitable for limiting the distance between first chamber barrier layer  245  and second chamber barrier layer  250  of chamber  240  when inflated. For example, tensile member  255  may have any of the configurations disclosed in Dua, U.S. Pat. No. 8,151,486, issued Apr. 10, 2012, and entitled “Fluid-Filled Chamber with a Textile Tensile Member;” Peyton et al., U.S. Patent Application Publication No. 2011/0131831, published Jun. 9, 2011, and entitled “Tethered Fluid-Filled Chambers,”; and Hazenberg et al., U.S. Patent Application Publication No. 2013/0266773, published Oct. 10, 2013, and entitled “Spacer Textile Materials and Methods for Manufacturing the Spacer Textile Materials,” the entire disclosures of which are incorporated herein by reference. 
     In some configurations, tethers  270  may include a plurality of substantially planar slats. In some configurations, such slats may be arranged in a substantially vertical orientation. In other embodiments, such slats may be angled with respect to first chamber barrier layer  245  and second chamber barrier layer  250 . Further, such slats may be oriented in any suitable direction. For example, in some embodiments, the slats may be oriented in a substantially lateral direction. In other embodiments, the slats may be oriented in a substantially longitudinal direction. Other orientations are also possible. Tethers  270  may have any of the planar configurations disclosed in Dua, U.S. Pat. No. 8,151,486, issued Apr. 10, 2012, and entitled “Fluid-Filled Chamber with a Textile Tensile Member.” 
     In some configurations, tethers  270  may include a plurality of strand-like members having a substantially one-dimensional configuration. For example, tethers  270  may each have a length between first tensile member layer  260  and second tensile member  265 . This length may be substantially greater than the width or thickness of the one-dimensional tethers. Tethers  270  may have any of the one-dimensional configurations disclosed in Peyton et al., U.S. Patent Application Publication No. 2011/0131831, published Jun. 9, 2011, and entitled “Tethered Fluid-Filled Chambers.” 
     Tethers  270  may be formed of any suitable material. For example in some embodiments, tethers  270  may be formed of a polymer material. In some embodiments, tensile member  255  may be formed of a three-dimensional fabric (3-D fabric). Tensile member  255  may be formed as a unitary (i.e., one-piece) textile element having the configuration of a spacer-knit textile. A variety of knitting techniques may be utilized to form tensile member  255  and impart a specific configuration (e.g., taper, contour, length, width, thickness) to tensile member  255 . In general, knitting involves forming courses and wales of intermeshed loops of a yarn or multiple yarns. In production, knitting machines may be programmed to mechanically-manipulate yarns into the configuration of tensile member  255 . That is, tensile member  255  may be formed by mechanically-manipulating yarns to form a one-piece textile element that has a particular configuration. The two major categories of knitting techniques are weft-knitting and warp-knitting. Whereas a weft-knit fabric utilizes a single yarn within each course, a warp-knit fabric utilizes a different yarn for every stitch in a course. In some embodiments, tensile member  255  may be formed using double needle bar Raschel knitting. In some embodiments, tensile member  255  may be formed using configurations disclosed in Hazenberg et al., U.S. Patent Application Publication No. 2013/0266773, published Oct. 10, 2013, and entitled “Spacer Textile Materials and Methods for Manufacturing the Spacer Textile Materials.” 
     In some embodiments, all of tethers  270  may have substantially the same length, thus providing tensile member  255  with a substantially constant thickness. In other embodiments, tethers  270  may have different lengths. In some embodiments, first tensile member layer  260  and second tensile member layer  260  may each have a generally continuous and planar configuration. In some embodiments, first tensile member layer  260  and second tensile member layer  265  may be substantially parallel to one another. In other embodiments, tensile member  255  may have a tapered configuration. For example, in some embodiments, tensile member  255  may have a tapered configuration between heel region  140  and forefoot region  130 . In order to impart the tapered configuration, the lengths of tethers  270  may decrease between heel region  140  and forefoot region  130 . Exemplary tapered chamber configurations are disclosed in Dua, U.S. Pat. No. 8,151,486, issued Apr. 10, 2012, and entitled “Fluid-Filled Chamber with a Textile Tensile Member.” 
     In some embodiments, one or both of first tensile member layer  260  and second tensile member layer  260  may have a contoured configuration. For example, in some embodiments, first tensile member layer  260  may have a concave configuration to conform to the anatomical shapes of the foot. A depression in heel region  140  may cradle the heel of a wearer and more evenly distribute contact forces between chamber  240  and the foot of the wearer. Exemplary contoured chamber configurations are disclosed in Dua, U.S. Pat. No. 8,151,486, issued Apr. 10, 2012, and entitled “Fluid-Filled Chamber with a Textile Tensile Member;” and Peyton et al., U.S. Patent Application Publication No. 2011/0131831, published Jun. 9, 2011, and entitled “Tethered Fluid-Filled Chambers.” 
     In some embodiments, tensile member  255  may include multiple sections. For example, as shown in  FIG.  2   , tensile member  255  may include a first tensile member section  281  corresponding with a first chamber portion  285 . Tensile member  255  may also include a second tensile member section  282  corresponding with a second chamber portion  290 . Further, tensile member  255  may include a third tensile member section  283  corresponding with a third chamber portion  295 . 
     In some embodiments, midsole  115  may include a recess  300  configured to receive chamber  240 . First chamber portion  281  may be received by a first portion of recess  300  including a heel recess region  305 , a midfoot recess region  310 , and a first forefoot recess region  315 . This first portion of recess  300  may be separated from a second forefoot recess region  320  by third elongate rib  220 . Second forefoot recess region  320  may receive second chamber portion  290 . Further, second forefoot recess region  320  may be separated from a third forefoot recess region  325  by fourth elongate rib  235 . Third forefoot recess region  325  may receive third chamber portion  295 . 
     As shown in  FIG.  2   , spaces between the chamber portions may form indentations. For example, the space between first chamber portion  285  and second chamber portion  290  may form a first elongate indentation  275 , as shown in  FIG.  2   . Similarly, the space between second chamber portion  290  and third chamber portion  295  may form a second elongate indentation  280 . In some embodiments, first elongate indentation  275  may receive third elongate rib  220  of third flex groove portion  210  of midsole  115 , in a nesting relationship. Second elongate indentation  275  may receive fourth elongate rib  235  of midsole  115 , also in a nesting relationship. 
     The nested relationships between the ribs of outer member  120  and the recesses of midsole  115 , as well as the nesting relationships between the ribs of midsole  115  and the indentations of chamber  240 , may enable sole structure  105  to have a thinner profile. That is, the overall thickness of sole structure  105  as formed by the combination of sole structure components (outer member  120 , midsole  115 , and chamber  240 ) may be reduced. For example, a wearer&#39;s foot may be located lower to the ground than if the entirety of midsole  115  were located at the raised height of first elongate rib  165  and second elongate rib  190 . Similarly, a wearer&#39;s foot may be located lower to the ground than if the entirety of chamber  240  were located at the raised height of third elongate rib  220  and fourth elongate rib  235 . 
     The reduced overall thickness of sole structure  105  provided by the nesting relationships of sole structure components may increase the stability and responsiveness of sole structure  105 . Alternatively, or additionally, the reduced overall thickness, which is made possible by the nesting relationships of sole structure components, may provide more space for sole structure components. For example, because most of midsole  115  may be positioned lower to the ground, thicker cushioning elements, such as chamber  240 , may be utilized in conjunction with midsole  115  without unduly raising the footbed of footwear  110 . 
     As shown in  FIG.  2   , first tensile member layer  260  may extend continuously between first tensile member section  281 , second tensile member section  282 , and third tensile member section  282 . Second tensile member layer  265  may be discontinuous. For example, second tensile member layer  265  may include a first tensile member layer section  271 , a second tensile member layer section  272 , and a third tensile member layer  273 . First tensile member layer section  271  may be separated from second tensile member layer section  272  by a gap corresponding with first indentation  275 . Second tensile member layer section  272  may be separated from third tensile member layer section  273  by a gap corresponding with second indentation  280 . 
     It will be noted that, although first elongate indentation  275  and second elongate indentation are shown in  FIG.  2    as being substantially laterally oriented, in some embodiments, the configuration of elongate indentations in chamber  240  may have any suitable orientation. In addition, the number of elongate indentations may vary. Additional elongate indentations may provide chamber  240  with additional flexibility. 
       FIG.  3    is a cross-sectional view taken at section line  3 - 3  of  FIG.  2   . In particular,  FIG.  3    illustrates a cross-sectional view of chamber  240  through second indentation  280 . As shown in  FIG.  3   , first chamber barrier layer  245  extends across second chamber portion  290  and third chamber portion  295 . As discussed above, first tensile member layer  260  may extend continuously between second tensile member section  282  and third tensile member section  283 . Further, as also discussed above, second tensile member layer  265  may include second tensile member layer section  272  and a third tensile member layer section  273 , which may be separated by a gap  330 . 
     In order to provide second tensile member layer  265  with separate sections, a portion of first tensile member layer  260  may be omitted to form gap  330 . In some embodiments, the portions of material may be omitted during manufacturing of tensile member  255 . In some embodiments, the portions of material may be removed from tensile member  255 . For example, in some embodiments, the material may be removed by cutting tools, such as lasers, blades, cutting wheels, shears, or other suitable cutting implements. 
     As shown in  FIG.  3   , a portion  335  of second chamber barrier layer  250  extends upward in gap  330  toward first tensile member layer  260  between second tensile member layer section  272  and third tensile member layer section  273  of second tensile member layer  265 . Portion  335  of second chamber barrier layer  250  that extends toward first tensile member layer  260  may be joined to first tensile member layer  260 . That is, portion  335  of the bottom barrier layer extends upward between the second tensile member layer section  272  and third tensile member layer section  273  of second tensile member layer  265  and joins to a lower surface  340  of first tensile member layer  260 . 
     In order to facilitate this joinder of first tensile member layer  260  with second chamber barrier layer  250 , first tensile member layer  260  may be formed of a material that is suited for bonding with second chamber barrier layer  250 . In some embodiments, first tensile member layer  260  may be formed of a material that is configured to provide added strength in order to compensate for at least some of the effect of having a portion of second tensile member layer  265  omitted. Such added strength may be provided by selecting a stronger material and/or by increasing the amount of material used (e.g., the thickness) for first tensile member layer  260 . In some embodiments, first tensile member layer  260  may be constructed in a manner that provides increased strength. For example, in some embodiments where first tensile member layer  260  is a textile, different knitting/weaving processes may be used to provide added strength. 
     By joining portion  335  of second chamber barrier layer  250  to first tensile member layer  260 , several advantages may be provided. For example, this configuration provides chamber  240  with flexibility. This flexibility is provided by several aspects of this configuration. By joining portion  335  of second chamber barrier layer  250  to first tensile member layer  260 , the thickness of chamber  240  may be reduced in that area. As shown in  FIG.  3   , chamber  240  may have a first thickness  345  at the junction between portion  335  of second chamber barrier layer  250  and first tensile member layer  260 . Chamber  240  may have a second thickness  350  over a majority of chamber  240 . As shown in  FIG.  3   , first thickness  345  of chamber  240  may be less than second thickness of chamber  240 . This reduced thickness may act as a living hinge, thus enabling flexion between second chamber portion  290  and third chamber portion  295 . 
     Joining portion  335  of second chamber barrier layer  250  to first tensile member layer  260  also defines second indentation  280 , which may receive flex groove portions of mating sole structure components. This enables the sole structure components to have a nesting relationship that provides the sole structure with a thinner profile. As discussed above, this thinner profile may provide the footwear with stability and responsiveness. 
     In addition, although second tensile member layer  265  is separated into multiple sections, such as second tensile member layer section  272  and third tensile member layer section  273 , first tensile member layer  260  remains continuous across multiple sections of chamber  240 . Thus, tensile member  255  may be a fully pre-formed structure prior to assembly into chamber  240 . Tensile member  255  being a fully pre-formed structure may facilitate positioning of tensile member  255  during assembly, because there are no separate pieces that may become out of place with respect to one another when pressed between first chamber barrier layer  245  and second chamber barrier layer  250 . 
     In some embodiments, the sole structure may omit the midsole layer between the chamber and outsole. That is, the chamber may be secured directly to the outer member of the sole structure. In such embodiments, the indentations of the chamber may receive the elongate ribs of the flex groove portions of the outer member of the sole structure. In some cases, such a configuration may provide the sole structure with an even lower profile. In some embodiments, a midsole may be located above the chamber. That is, in some cases, the chamber may be disposed between the midsole and the outsole. 
       FIG.  4    shows an article of footwear  400 . Footwear  400  may include a sole structure  405  secured to an upper  410 . Sole structure  405  may include an outer member  415  and a chamber  440 .  FIG.  4    shows footwear  400  in an articulated position with the heel portion raised in the direction of an arrow  430 . This articulation is indicated by flexion of a first flex groove portion  420  and a second flex groove portion  425  of outer member  415 . In addition, this articulation also involves the flexion of a first indentation  475  and a second indentation  480  in chamber  440 . 
     Like chamber  240  discussed above, chamber  440  may include a first chamber barrier layer  445  and a second chamber barrier layer  450 . In addition, chamber  440  may also include a tensile member  455  bonded to first chamber barrier layer  445  and second chamber barrier layer  450 , and configured to limit the spacing between these barrier layers when chamber  440  is pressurized. Tensile member  455  may include a first tensile member layer  460  and a second tensile member layer  465 . Tensile member  455  may also include a plurality of tethers  470  connecting first tensile member layer  460  to second tensile member layer  465 . Characteristics of the components of footwear  400  and chamber  440  discussed above may be substantially similar to corresponding components discussed above regarding other embodiments. 
     As shown in  FIG.  4   , wherein the portion of second chamber barrier layer  450  that extends toward first tensile member layer  460  defines first elongate indentation  475  in chamber  440 . As shown in  FIG.  4   , first elongate indentation  475  may receive a first elongate rib formed by first flex groove portion  420  of outer member  415 . Similarly, second elongate indentation  480  may receive a second elongate rib formed by second flex groove portion  425 . 
     In some embodiments, chambers having multiple sections may be incorporated into sole structures that may or may not include a midsole. Accordingly, in some embodiments, the sole structure may include a midsole that includes elongate ribs that may nest within elongate indentations in the chamber. In other embodiments, the sole structure may include an outer member that includes elongate ribs that may nest within elongate indentations in the chamber. Thus, the sole structure may include an additional sole structure component, the additional sole structure component including at least one of a midsole and an outer member exposed to the ground. The additional sole structure component may have an upper surface and a lower surface. Further, the additional sole structure component may have a flex groove portion including an elongate recess in the bottom surface and a corresponding elongate rib on the upper surface. The portion of the bottom barrier layer that extends upward between a first section and a second section of a second tensile member layer may define an elongate indentation in the chamber that receives the elongate rib of the flex groove portion of the additional sole structure component. 
       FIG.  5    illustrates an isolated view of chamber  440  shown in an articulated configuration. As shown in  FIG.  5   , second tensile member layer  465  may be formed as multiple separate sections, such as a first tensile member layer section  501 , a second tensile member layer section  502 , and a third tensile member layer section  503 . First elongate indentation  475  of chamber  440  may be located between first tensile member layer section  501  from second tensile member layer section  502 . Similarly, second elongate indentation  480  may be located between second tensile member layer section  502  and third tensile member layer section  503 . As shown in  FIG.  5   , flexion of chamber  440  in the direction of arrow  485  may result in the articulation of chamber  440  at a first flex line  490  corresponding with first elongate indentation  475  and a second flex line  495  corresponding with second elongate indentation  480 . 
       FIG.  6    is a cross-sectional view of chamber  440  taken at section line  6 - 6  in  FIG.  5   . As shown in  FIG.  6   , a portion  505  of second chamber barrier layer  450  may extend upward between second tensile member layer section  502  and third tensile member layer section  503 . As further shown in  FIG.  6   , section  505  of second chamber barrier layer  450  may be joined to a lower surface  510  of first tensile member layer  460 .  FIG.  6    further illustrates the articulation of chamber  440  by flexion at second flex line  495 . As shown in  FIG.  6   , chamber  440  may be flexed at an angle illustrated by angle  515 . Angle  515  is an exemplary angle and is not intended to indicate the limit to which chamber  440  may be flexed. 
       FIG.  7    shows an exploded view of chamber components, and a die set for joining portions of the chamber components to one another. In particular,  FIG.  7    illustrates an exploded view of chamber  440 . As shown in  FIG.  7    chamber  440  may include a first adhesive layer  730  between first chamber barrier layer  445  and first tensile member layer  460  and a second adhesive layer  735  between second chamber barrier layer  450  and second tensile member layer  465 . First adhesive layer  730  and second adhesive layer  735  may be any suitable adhesive for joining the barrier layers to the tensile member layers. For example, in some embodiments, adhesive layer  730  and second adhesive layer  735  may include a hot melt adhesive. Adhesive layer  730  and second adhesive layer  735  are omitted from other drawings of the application for purposes of clarity. 
     For purposes of illustration,  FIG.  7    shows a portion of chamber  440  corresponding with that shown in  FIG.  6   . In  FIG.  7   , however, chamber  440  is oriented in an opposite direction than in  FIG.  6   . That is, while the completed chamber may be oriented with the flex groove facing downward, as shown in  FIG.  6   , the chamber may be assembled upside down during the manufacturing process, as described further below. 
     In some embodiments, tensile member  455  may have two sections. As shown in  FIG.  7   , second tensile member layer  465  may be discontinuous between the two sections. For example, as shown in  FIG.  7   , second tensile member layer  465  may include a first portion  502  and a second portion  503  separate from first portion  502  by a gap  725 . In contrast, first tensile member layer  460  may extend continuously between the first tensile member section and the second tensile member section, as shown in  FIG.  7   . 
     As shown in  FIG.  7   , a first process of the manufacturing method may utilize a first die set  700 . First die set  700  may include a first die  705  and a second die  710 . First die set  700  may be configured to draw first barrier layer  445  against first die  705  using vacuum pressure. For example, in some embodiments, first die  705  may include one or more air passages  711  through which air may be removed to create vacuum pressure (i.e., reduced pressure) in order to draw first barrier layer  445  against first die  705 , thereby conforming first barrier layer  445  to the contours of first die  705 . Similarly, second die  710  may include one or more air passages  712  through which air may be removed in order to draw second chamber barrier layer  450  against second die  710 , thereby conforming second chamber barrier layer  450  to the contours of second die  710 . For example, second die  710  may include an elongate projection  740 . By drawing second chamber barrier layer  450  against second die  710 , second chamber barrier layer  450  may conform to the contours of elongate projection  740 . 
     Arranging the plurality of chamber components in a stacked arrangement may involve locating tensile member  455  between first chamber barrier layer  445  and second chamber barrier layer  450 . The method may include placing the stacked arrangement of chamber components into first die set  700 . In some embodiments, the stacked arrangement of chamber components may be placed within the die set together. In some embodiments, the stacked arrangement of chamber components may be individually inserted into the die set. For example, in some embodiments, first chamber barrier layer  445  may be drawn against first die  705  using vacuum pressure, and second chamber barrier layer  450  may be drawn against second die  710 . Then, tensile member  455  may be placed between first chamber barrier layer  445  and second chamber barrier layer  450 . 
     In some embodiments, the method of forming chamber  440  may include two processes.  FIGS.  7  and  8    illustrate a first process of the method. The first process may include bonding first chamber barrier layer  445  to the second chamber barrier layer  450  to form peripheral portions of the chamber. 
     The first process may also include joining a portion of second chamber barrier layer  450  to first tensile member layer  460 . In some embodiments, not only may the first die set be used to join the chamber barrier layers to the tensile member, but the first die set may also be used to seal the peripheral portions of the chamber barrier layers. First die  705  may include a first peripheral die projection  905  extending toward second die  710 . Second die  710  may include a second peripheral die projection  910  extending toward first die  705 . In some embodiments, the bonding and joining steps of the first process may be performed simultaneously in first die set  700  as part of the first process. 
     In order to perform these bonding and joining steps, the first process may include applying pressure to the stacked arrangement of chamber components to join portions of the chamber components to one another. For example, the method may include applying heat and pressure by compressing a stacked arrangement of components of chamber  440  between first die  705  and second die  710 . This compression may be accomplished by applying force with first die  705  in a direction indicated by a first arrow  715  and by applying an opposite force with second die  710  in an opposite direction indicated by a second arrow  720 . 
       FIG.  8    illustrates the use of first die set  700  to bond portions of the stacked arrangement of chamber components shown in  FIG.  7   . When pressure is applied with first die  705  and second die  710 , elongate projection  740  may fixedly attach second chamber barrier layer  450  to first tensile member layer  460  in gap  725 . As shown in  FIG.  8   , applying pressure to the stacked arrangement of chamber components with first die  705  and second die  710  may extend elongate projection  740  of second die  710  into gap  725  between first tensile member layer section  502  and second tensile member layer section  503  and presses second chamber barrier layer  450  against first tensile member layer  460 . 
     In addition, as also shown in  FIG.  8   , when first die  705  and second die  710  are compressed together, a first peripheral barrier layer portion of first chamber barrier layer  445  may be compressed against and joined to a second peripheral barrier layer portion of second chamber barrier layer  450  between first peripheral die projection  905  and second peripheral die projection  910  to form a bonded peripheral edge  925  of chamber  440 . 
     As shown in  FIG.  8   , the height of elongate projection  740  may be tall enough that, when elongate projection  740  engages against first tensile member layer  460 , the opposing surfaces of first die  705  and second die  710  may be separated by a first distance  805 . This distance  805  may be greater than the thickness of the stacked arrangement of chamber components. Accordingly, while second chamber barrier layer is held against second die  710 , second tensile member layer  465  may rest on the bottom of the cavity within die set  700  under the influence of gravity. Therefore, in  FIG.  8   , tethers  470  are shown in an unextended or slackened condition. Because of this die set configuration, tensile member  455  is not bonded to first barrier layer  445  or second barrier layer  450  during this first process of the method of the manufacturing method of forming chamber  440 . 
     In some embodiments, the first process may be a thermoforming process. Thermoforming is a manufacturing process where a plastic sheet is heated to a pliable forming temperature, formed to a specific shape in a mold, and trimmed to create a usable product. To complete the first process described above with thermoforming one or both of first die  705  and second die  710  may be heated. 
       FIG.  9    shows a second process of a manufacturing method of forming the chamber shown in  FIG.  6   . As shown in  FIG.  9   , the second process may be completed by a second die set  900 . Second die set  900  may include a third die  905  and a fourth die  910 .  FIG.  9    also shows chamber  440  after completion of the first process of the manufacturing method with second chamber barrier layer fixedly attached to first tensile member layer  460  and with bonded peripheral edge  925  formed by the welding of first chamber barrier layer  445  with second chamber barrier layer  450 . Also, after completion of the first process, chamber  440  may have an elongate indentation, which may form a flex groove  480 . 
       FIG.  10    shows a further stage of the second process shown in  FIG.  9   .  FIG.  10    shows third die  905  and fourth die  910  being advanced toward one another to compress the chamber. Accordingly, the second process may include bonding first tensile member layer  460  to first chamber barrier layer  445 . In addition, the second process may include bonding second tensile member layer  465  to second chamber barrier layer  450 . Also, by compressing substantially the entire chamber, the steps of bonding first tensile member layer  460  to first chamber barrier layer  445  and bonding second tensile member layer  465  to second chamber barrier layer  450  are performed simultaneously in second die set  900  as part of the second process. 
     In some embodiments, third die  905  may include a die groove  920 . During the second process, the flex groove  915  may be aligned with die groove  920 . Accordingly, during the heating process, the bond that had already been formed between second chamber barrier layer  450  and first tensile member layer  460  would not be reheated significantly. 
     In some embodiments, the second process may utilize radiofrequency welding (RF welding) to perform the bonding steps of the second process. Radio frequency welding may also be referred to as “high frequency welding.” Radio frequency welding uses electromagnetic energy and pressure to weld and permanently bond thermoplastic, vinyl and coated fabrics to fixedly attach two components by forming a new, permanent bond. When cooled, the newly formed bond is as strong as or even stronger than the original materials. By using radio frequency welding, the heating/welding can be targeted at particular portions of the stacked arrangement of chamber components without reheating welds that were formed in the first (thermoforming) process. For example, only the portions corresponding to the sections of second tensile member layer  465 , and not at flex groove  915 . 
       FIG.  11    shows a further step of the method of forming the chamber shown in  FIG.  6   . As shown in  FIG.  11   , once the tensile member is bonded to the barrier layers of the chamber, the chamber may be inflated with a pressurized fluid. In some embodiments, the inflation may be performed while the chamber resides in the second die set. 
     As also shown in  FIG.  11   , in some embodiments, chamber  440  may be inflated with a pressurized fluid  940 . In some embodiments, the injection of pressurized fluid  940  may be performed while chamber  440  is compressed within second die set  900 . Upon pressurization, the top and bottom sides of chamber  440  may be extended up and down, respectively, increasing the height of the stacked arrangement of chamber components. This inflation of chamber  440  may extend tethers  470  and place tethers  470  in tension, as shown in  FIG.  11   . 
     Once the chamber is fully assembled, the method may include incorporating the chamber into the sole structure of the article of footwear. In addition, the method may include attaching the sole structure to the upper. 
       FIG.  12    shows an assembled, cross-sectional view of the chamber formed in the method shown in  FIGS.  7 - 11   . That is,  FIG.  12    illustrates chamber  440  after assembly using first die set  700  and second die set  900 . As shown in  FIG.  12   , first peripheral barrier layer portion  915  of first chamber barrier layer  445  is joined to second peripheral barrier layer portion  920  of second chamber barrier layer  450 . In some embodiments, the joinder of these portions of chamber  440  may form a flange, which may be trimmed after or during the sealing of first peripheral barrier layer portion  915  to second peripheral barrier layer portion  920 . 
     Tethers  470  may extend across the interior void within chamber  440  and are placed in tension by the outward force of the pressurized fluid upon first chamber barrier layer  445  and second chamber barrier layer  450 , thereby preventing chamber  440  from expanding outward and retaining the intended shape of chamber  440 . Whereas the peripheral bond of first peripheral barrier layer portion  915  to second peripheral barrier layer portion  920  joins the polymer sheets to form a seal that prevents the fluid from escaping, tensile member  455  prevents chamber  440  from expanding outward or otherwise distending due to the pressure of the fluid. That is, tensile member  455  effectively limits the expansion of chamber  440  to retain an intended shape of surfaces of first chamber barrier layer  445  and second chamber barrier layer  450 . 
       FIG.  12    illustrates chamber  440  right side up, with flex groove  480  facing downward as it may be when incorporated in an article of footwear. In this orientation, as shown in  FIG.  12   , a portion of the bottom barrier layer (i.e., second barrier layer  450 ) extends upward in the gap  725  between first tensile member layer section  502  and second tensile member layer section  503 . Further, the bottom barrier layer (i.e., second barrier layer  450 ) is joined to the lower surface  510  of first tensile member layer  460 . 
     In some embodiments, the chamber may be configured such that the chamber barrier layer may be angled in the area where it extends between sections of the tensile member. For example, in some embodiments, the portion of the lower chamber barrier layer that extends upward toward the upper tensile member layer may extend from the lower tensile member layer to the upper tensile member layer at an angle that is non-perpendicular with respect to the upper tensile member layer. Such an angled configuration may provide stability and control of shear forces within the chamber. 
       FIG.  13    shows a chamber  1140  including a first chamber barrier layer  1145  and a second chamber barrier layer  1150 . Chamber  1140  may also include a tensile member  1155 , which may include a first tensile member layer  1160  and a second tensile member layer  1165 . A plurality of tethers  1170  may extend between first tensile member layer  1160  and second tensile member layer  1165 . Second tensile member layer  1165  may include separate sections, such as a first tensile member layer section  1101  and a second tensile member layer section  1102 . The characteristics of these components may be the same or similar to corresponding components of other embodiments discussed above. 
     As shown in  FIG.  13   , a portion  1105  of second chamber barrier layer  1150  may extend toward and be fixedly attached to a lower surface  1110  of first tensile member layer  1160 , thus forming an elongate indentation  1180  in chamber  1140 . As further shown in  FIG.  13   , at least one area of portion  1105  of second chamber barrier layer  1150  that extends toward first tensile member layer  1160  may extend from second tensile member layer  1165  to first tensile member layer  1160  at an angle  1115  that is non-perpendicular with respect to first tensile member layer  1160 . That is, at least one area of the portion of the bottom barrier layer that extends upward in the gap between the first tensile member layer section and the second tensile member layer section extends from the second tensile member layer to the first tensile member layer at an angle that is non-perpendicular with respect to the first tensile member layer. Angle  1115  may be any suitable non-perpendicular angle. Smaller angles may provide the angled portion of second chamber barrier layer  1150  with a more horizontal configuration, thus providing greater amounts of stability and horizontal support. 
     When assembling the chamber, the distance between the bonded area between the chamber barrier layer and the tensile member layer and the edge of the tensile member layer adjacent the gap may be taken into consideration when sizing the first die set. In particular, the ratio between the height of the projection that extends into the gap and the height between the upper and lower dies of the first die set may determine how close to the edge of the second tensile member layer the bonded area between the second chamber barrier layer and the first tensile member layer may be formed. This ratio may influence the angle of the chamber barrier layer in the gap between sections of the tensile member layer. 
     Although  FIG.  13    illustrates chamber  1140  fully assembled, For purposes of illustration,  FIG.  13    shows a die  1195  in place for reference. For simplicity, the opposing die is not shown. Die  1195  includes a projection  1180 , which may be used to extend second barrier layer  1150  into the gap and bond it to first tensile member layer  1160 . During that process, second chamber barrier layer  1150  may be drawn tightly against die  1195 , as shown by dashed line  1186 . Once the die is removed, and chamber  1140  is inflated, second chamber barrier layer  1150  may be tightened and, therefore, move in a direction indicated by arrow  1188  and arrow  1190  to form the angled configuration of second chamber barrier layer  1150 . The amount to which the barrier layer becomes angled depends on the ratio of the height of projection  1180  and the height between die  1195  and it&#39;s opposing die. The amount to which the barrier layer becomes angled may also depend on the distance  1184  between edge  1182  of second tensile member layer  1182  and the bonded area between second chamber barrier layer  1150  and first tensile member layer  1160 . It will be noted that the dimensions and proportions shown in the drawings are schematic and not necessarily to scale. 
     In some embodiments where the gap between sections of the tensile member sections is smaller, the amount of the bottom chamber barrier layer that is unlined with tensile member is minimized. This may increase the structural integrity of the chamber, and simplify the construction of the assembly. For example, a smaller portion of the tensile member layer may be omitted/removed to create the gap between tensile member sections. 
     In order to narrow the distance between the bonded area between the second chamber barrier layer and the first tensile member layer and the edge of the second tensile member layer, more length of the second tensile member layer may be gathered during the first process of the manufacturing method. In particular, elongate recesses may be located on opposing sides of the projection. The second chamber barrier layer may be drawn into the elongate recesses, so that, when the chamber is assembled and inflated, there is more length of chamber barrier layer to form the walls of the flex groove. 
       FIG.  14    shows another die configured to perform a portion of a method of forming a chamber. For simplicity,  FIG.  14    shows only a first die  1400  and a first chamber barrier layer  1405 . As shown in  FIG.  14   , die  1400  may include one or more vacuum holes, through which air may be removed to create a vacuum pressure in order to draw first chamber barrier layer  1405  against a surface  1445  of die  1400 . For example, die  1400  may include a first vacuum hole  1420 , a second vacuum hole  1425 , a third vacuum hole  1430 , and a fourth vacuum hole  1435 . 
     In some embodiments, surface  1445  may be a substantially planar die surface. Die  1400  may include an elongate projection  1440  for extending first chamber barrier layer  1405  into a gap between sections of a tensile member layer. In some embodiments, elongate projection  1440  may have a substantially trapezoidal cross-sectional shape, as also shown in  FIG.  14   . Further, die  1400  may include a first elongate recess  1410  adjacent elongate projection  1440 . Die  1400  may also include a second elongate recess  1415  adjacent elongate projection  1440  on an opposite side of elongate projection  1440  from first elongate recess  1410 . 
       FIG.  15    shows the die of  FIG.  14    with a chamber barrier layer drawn against it using vacuum pressure. That is, the method may include drawing first chamber barrier layer  1405  against die  1400  by creating a reduced pressure using a vacuum, so that first chamber barrier layer  1405  extends into first elongate recess  1410  and second elongate recess  1415 . This collects extra length of first chamber barrier layer  1405  in a first portion  1450  and a second portion  1460 . First portion  1450  provides additional length to the barrier layer that adds to the height of the flex groove that will be formed. This additional length is represented by first dimension  1455 . Similarly, second portion  1460  provides additional length represented by second dimension  1465 . As also shown in  FIG.  15   , the additional length drawn into first elongate recess  1410  and second elongate recess  1415  pulls first chamber barrier layer  1405  inward from its end points, as represented by a third dimension  1470 . 
       FIG.  16    shows an assembled and inflated chamber  1600  formed in the method including the process that is partially shown in  FIG.  15   . Chamber  1600  may include a second chamber barrier layer  1605 . Also, chamber  1600  may include a tensile member  1607 , which may include a first tensile member layer  1610  and a second tensile member layer  1615 . Tensile member  1607  may include a plurality of tethers  1620 . Extra height added to first chamber barrier layer  1405  by first elongate recess  1410  and second elongate recess  1415  is illustrated in  FIG.  16    by first portion  1450  of first chamber barrier layer  1405 . As shown in  FIG.  16   , first portion  1450  may have a first height  1475 . In addition, second portion  1460  may have a second height  1485 . 
     The added length provided to the chamber barrier layer in the flex groove may enable the edge of the tensile member to be closer to the bond between the barrier layer and the tensile member layer in the flex groove. In addition, if the height proportions between the elongate projection and the height of the first die set are selected accordingly, the chamber may be assembled using a single bonding process instead of two separate bonding processes. For example, in one step, in one die set, the first chamber barrier layer may be bonded to the second tensile member layer, the peripheral edges of the chamber barrier layers may be welded, and the tensile member layers may be bonded to the first chamber barrier layer and the second chamber barrier layer. 
       FIG.  17    shows an assembled, cross-sectional view of another exemplary fluid-filled chamber. In particular,  FIG.  17    shows a chamber  1240  including a first chamber barrier layer  1245  and a second chamber barrier layer  1250 . Chamber  1240  may also include a tensile member  1255 , which may include a first tensile member layer  1260  and a second tensile member layer  1265 . A plurality of tethers  1270  may extend between first tensile member layer  1260  and second tensile member layer  1265 . Second tensile member layer  1265  may include separate sections, such as a first tensile member layer section  1201  and a second tensile member layer section  1202 . The characteristics of these components may be the same or similar to corresponding components of other embodiments discussed above. 
     As shown in  FIG.  17   , a portion  1205  of second chamber barrier layer  1250  may extend toward and be fixedly attached to a lower surface  1210  of first tensile member layer  1260 , thus forming an elongate indentation  1280  in chamber  1240 . As further shown in  FIG.  17   , at least one area of portion  1205  of second chamber barrier layer  1250  that extends toward first tensile member layer  1260  may extend from second tensile member layer  1265  to first tensile member layer  1260  at an angle  1281  that is non-perpendicular with respect to first tensile member layer  1260 . In addition, as also shown in  FIG.  17   , a first portion  1203  of second tensile member layer  1265  may be fixedly attached to the area portion  1205  of second chamber barrier layer  1250  that extends at non-perpendicular angle  1281 . A second portion  1204  of second tensile member layer  1265  may be arranged similarly to first portion  1203 . As shown in  FIG.  17   , in some embodiments, some of tethers  1270  that are attached to first portion  1203  and second portion  1204  may be less than fully extended when chamber  1240  is inflated. 
     It will also be noted that, although exemplary chambers disclosed herein are shown with the elongate indentations on a lower side, in some embodiments, the indentations may be provided on the upper side. Accordingly, in some embodiments, the upper barrier layer may extend downward toward, and join with, the lower tensile member layer. That is, the chambers may be configured with an arrangement that is essentially upside down from that shown in the accompanying figures. In such embodiments, with indentations on the upper side of the chamber, the indentations may enable articulation between sections of the chamber, while the thinner portions of the chamber (at the barrier layer/tensile member layer junction) act as living hinges. In some embodiments, the bonding of a portion of chamber barrier layer to an opposing portion of tensile member layer in a gap between sections of the tensile member may form opposing indentations or flex grooves in the chamber. For example, opposing flex grooves may extend into the top and bottom surfaces of the chamber. 
     In some configurations, the chamber may be formed without the elongate indentation where the lower chamber barrier layer extends upward to join to the upper tensile member layer. Such configurations may be used, for example, in footwear embodiments that do not include flex grooves in sole structure components. For instance, the midsole may include a continuous recess that is not broken up by elongate ribs corresponding with flex groove portions. 
       FIGS.  13  and  14    show a chamber  1340  including a first chamber barrier layer  1345  and a second chamber barrier layer  1350 . Chamber  1340  may also include a tensile member  1355 , which may include a first tensile member layer  1360  and a second tensile member layer  1365 . A plurality of tethers  1370  may extend between first tensile member layer  1360  and second tensile member layer  1365 . Second tensile member layer  1365  may include separate sections, such as a first tensile member layer section  1301  and a second tensile member layer section  1302 . The characteristics of these components may be the same or similar to corresponding components of other embodiments discussed above. 
     As shown in  FIG.  13   , a portion  1305  of second chamber barrier layer  1350  may extend toward and be fixedly attached to a lower surface  1310  of first tensile member layer  1360 . As further shown in  FIG.  13   , a portion  1326  of second chamber barrier layer  1350  may be substantially folded upon itself, thus substantially eliminating the space between chamber sections. This configuration enables the gap  1325  between first tensile member layer section  1301  and second tensile member layer section  1302  to be minimized. 
     As shown in  FIG.  14   , when chamber  1340  is articulated, the sections of chamber  1340  may hingedly rotate about the junction between portion  1305  of second chamber barrier layer  1350  and lower surface  1310  of first tensile member layer  1360 . This hinge-like articulation may separate sections of chamber  1340 , thereby forming an opening  1380 . This configuration may be formed with a very narrow projection in the die, and with relatively deep elongate recesses on opposing sides of the projection. 
     It will be noted that the disclosed chamber configurations and tensile member arrangements may be implemented in articles other than footwear. For example, such chambers may be used for other articles such as garments and sporting equipment. In some cases, such chambers may be used to provide padding for sports garments, and the disclosed elongate indentations may provide flexibility that enables the padding to conform to the curvatures of various parts of the body. In other cases, such chambers may be used to provide padding in sports equipment, such as baseball gloves, catchers padding, lacrosse and football pads, and other such equipment. The flexibility of such chambers may enable such equipment to not only conform with the curvature of various parts of the body, but also to enable articulation of adjoined components of the equipment. 
     While various embodiments of the invention have been described, the description is intended to be exemplary, rather than limiting, and it will be apparent to those of ordinary skill in the art that many more embodiments and implementations are possible that are within the scope of the invention. Although many possible combinations of features are shown in the accompanying figures and discussed in this detailed description, many other combinations of the disclosed features are possible. Therefore, it will be understood that any of the features shown and/or discussed in the present disclosure may be implemented together in any suitable combination and that features of one embodiment may be implemented in other disclosed embodiments. Accordingly, the invention is not to be restricted except in light of the attached claims and their equivalents. Also, various modifications and changes may be made within the scope of the attached claims.