Patent Publication Number: US-11389704-B2

Title: Recovery materials for core constructs and methods for repairing core constructs

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. patent application Ser. No. 16/107,515, filed 21 Aug. 2018, which is a continuation-in-part of U.S. patent application Ser. No. 15/235,206, filed Aug. 12, 2016, each of which is incorporated herein by reference in its entirety for any and all non-limiting purposes. 
    
    
     FIELD 
     This disclosure relates generally to fabrication of molded structures. More particularly, aspects of this disclosure relate to core structures formed with a recovery material. The recovery material can be configured to repair cracks that form in an internal core. 
     BACKGROUND 
     Certain sporting implements may be formed with a central portion or a core. For example, a hockey stick blade can be formed of a core reinforced with one or more layers of synthetic materials such as fiberglass, carbon fiber or Aramid. Cores of hockey stick blades may also be made of a synthetic material reinforced with layers of fibers. The layers may be made of a woven filament fiber, preimpregnated with resin. These structures may include a foam core with a piece of fiber on the front face of the blade and a second piece of fiber on the rear face of the blade, in the manner of pieces of bread in a sandwich. 
     Cores of sporting implements may be subject to cracking or breaking over time. For example, a hockey stick blade core may crack during its normal use during play. This can induce a softening of the product, and may eventually lead to a break of the blade or stick. Nevertheless, adding a significant amount of material may increase the weight of the blade and stick, and the use of softer core materials may lead to breakage of the outer layer of the sporting implement because of the amount of movement of the outer layer allowed by the core. In the case of a hockey stick blade, this may also create a “trampoline effect” that may make the puck bounce off of the blade that is more than desired. Also the use of a harder material for the core, may in certain instances, be either be too fragile or too heavy. Moreover, omitting the foam core in a hockey stick blade may create a different “feel” of the stick to the player because of the lack of damping. 
     SUMMARY 
     The following presents a general summary of aspects of the disclosure in order to provide a basic understanding of the invention and various features of it. This summary is not intended to limit the scope of the invention in any way, but it simply provides a general overview and context for the more detailed description that follows. 
     Aspects of this disclosure relate to reducing the amount of cracks in a core material by absorbing energy between the outer layer, which can be a carbon skin, and the core material. If cracks form in the core, a layer of material can be configured to fill the cracks and to reduce the stiffness losses in the core. This may help to allow for more consistency during use of the sporting implement and allow the sporting implement to be used for a longer period of time. 
     Other objects and features of the disclosure will become apparent by reference to the following description and drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       A more complete understanding of the present disclosure and certain advantages thereof may be acquired by referring to the following detailed description in consideration with the accompanying drawings, in which: 
         FIG. 1  generally illustrates a partial cross-section and perspective view of an example hockey stick in accordance with an aspect of the disclosure; 
         FIG. 2A  shows a side view of an example core in accordance with an aspect of the disclosure; 
         FIG. 2B  shows a cross-sectional and front perspective view of the example core of  FIG. 2A  in accordance with an aspect of the disclosure; 
         FIG. 3A  shows a cross-sectional view of an example blade in accordance with an aspect of the disclosure; 
         FIG. 3B  shows another cross-sectional view of the example blade of  FIG. 3A  in a molding operation in accordance with an aspect of the disclosure; 
         FIG. 3C  shows an enlarged view of  FIG. 3A  in accordance with an aspect of the disclosure; 
         FIG. 4A  shows yet another cross-sectional view of the example blade of  FIG. 3A  during a molding operation in accordance with an aspect of the disclosure; 
         FIG. 4B  shows an enlarged view of the example blade of  FIG. 3A  after a molding operation in accordance with an aspect of the disclosure; 
         FIG. 5A  shows a cross-sectional view of the example blade of  FIG. 3A  after a crack is formed in accordance with an aspect of the disclosure; 
         FIG. 5B  shows a cross-sectional view of the example blade of  FIG. 3A  showing a recovery gel entering the crack is formed in  FIG. 5A  in accordance with an aspect of the disclosure. 
         FIG. 5C  shows a cross-sectional view of the example blade of  FIG. 3A  showing a recovery gel sealing the crack formed in  FIG. 5A  in accordance with an aspect of the disclosure. 
         FIGS. 6A-6C  show example recovery gel application patterns. 
         FIG. 7  shows an exemplary process for forming an example blade in accordance with an aspect of the disclosure. 
         FIG. 8  schematically depicts a cross-sectional view of an example blade that includes a dilatant material, according to one or more aspects described herein. 
         FIG. 9  schematically depicts another cross-sectional view of an example blade that includes a dilatant material in combination with a recovery gel, according to one or more aspects described herein. 
         FIG. 10  schematically depicts a view of one implementation an internal structure of a hockey stick blade, according to one or more aspects described herein. 
         FIG. 11  schematically depicts a view of another implementation an internal structure of a hockey stick blade, according to one or more aspects described herein. 
         FIG. 12  schematically depicts a view of another implementation an internal structure of a hockey stick blade, according to one or more aspects described herein. 
         FIG. 13  schematically depicts a view of another implementation an internal structure of a hockey stick blade, according to one or more aspects described herein. 
     
    
    
     The reader is advised that the attached drawings are not necessarily drawn to scale. 
     DETAILED DESCRIPTION 
     In the following description of various example structures in accordance with the invention, reference is made to the accompanying drawings, which form a part hereof, and in which are shown by way of illustration of various structures in accordance with the invention. Additionally, it is to be understood that other specific arrangements of parts and structures may be utilized, and structural and functional modifications may be made without departing from the scope of the present invention. 
     Also, while the terms “top” and “bottom” and the like may be used in this specification to describe various example features and elements of the disclosure, these terms are used herein as a matter of convenience, e.g., based on the example orientations shown in the figures and/or the orientations in typical use. Nothing in this specification should be construed as requiring a specific three dimensional or spatial orientation of structures in order to fall within the scope of the claims. 
     In general, as described above, aspects of this disclosure relate to the repair of a core structure. More specifically, aspects of the disclosure pertain to a recovery gel that can be used in conjunction with a sporting implement and methods for repairing a sporting implement, such as a hockey stick blade. More detailed descriptions of aspects of the disclosure follow. 
       FIG. 1  illustrates a perspective view an example structure utilizing a recovery gel with a section of the blade  104  partially cut away. In this example, the sporting implement can be a hockey stick  100 . However, it is contemplated that the repairing technique could be used in conjunction with other core structures outside of sporting implements and other types of sporting implements outside of hockey sticks, such as a lacrosse stick, bat, racquet, protective equipment, and the like. The example hockey stick  100  can include a handle or stick shaft  102  and a blade  104 . In this example, the blade  104  can include an outer layer  106 , a recovery gel  108 , and a core  110 . As discussed below, the outer layer  106  can be a skin formed of plies of carbon, which can be preimpregnated with a resin or can be formed as a dry material for use in a resin transfer molding (RTM) operation, The recovery gel  108  can form a gel skin layer over the core  110 . 
       FIG. 2A  shows a side view of the example core  110 , and  FIG. 2B  shows a cross-sectional view of the core  110 . As discussed below, in one example, the core  110  can be formed of a suitable foam. The core  110  can include a first core face  132 , a second core face  134 , a top core edge  136  and a bottom core edge  138 . 
     In certain examples, the core  110  can be an epoxy core and can be made of a B-staged epoxy resin, which can include additives and expandable microspheres. During the formation of the core, the expandable microspheres cause the core to expand when exposed to heat and create compaction force to compress plies forming the outer layer together. As will be discussed below, in one example, the epoxy core can be preformed inside a metal mold at 60° to 70° C. for 1 min so it has a shape that is close to the final geometry of the sporting implement, which in this case is a blade. An example epoxy core with expandable microspheres is discussed in U.S. Pat. No. 9,364,988, the entire contents of which are incorporated herein by reference for any and all non-limiting purposes. 
     In other examples, the core can be formed of a polymethacrylimide (PMI) foam, and may be a low density or a high density foam. In one example, a core structure is described in U.S. Pat. No. 9,295,890, the entire contents of which are incorporated herein by reference for any and all non-limiting purposes. It is further contemplated that additional or alternative foam types may be used in the hockey blade core. 
     The recovery gel  108  can be placed on both sides, e.g. the first core face  132  and the second core face  134 , of the preformed core  110  to provide a gel skin layer  108  that extends between the core  110  and the outer layer  106 . In this example, the recovery gel  108  only partially covers the blade in that the gel skin layer only extends along the first core face  132  and the second core face  134 . In other examples, the recovery gel  108  can be only applied to the front face, only to the back face, or only on the edges of the blade. Additionally, the recovery gel can be applied to only part of front face, part of back face, part of edges and various combinations of the above. However, in other examples, the recovery gel can form a film over the entire core of the blade including the first core face  132 , the second core face  134 , the top core edge  136 , and the bottom core edge  138 . 
       FIGS. 6A-6C  show different example applications of the recovery gel  108  applied to the core  110 . Generally, the recovery gel  108  can be applied to sections of the core  110  where the blade encounters the most impacts. For example, in the striking region of the blade between the heel and the toe. As shown in  FIG. 6A , the recovery gel  108  can be applied to the core  110  such that the recovery gel  108  tapers from the heel section to the toe section of the blade. Alternatively, as shown in  FIG. 6B , the recovery gel  108  can be applied as a rectangular shape to the core  110  and extends generally in the striking region of the blade. As shown in  FIG. 6C , the recovery gel  108  can be applied as small strips of material on the core  110  also in the striking region of the blade. In each of these examples, the patterns can be applied to both the front face and back face regions of the blade. In other examples, a different pattern can be applied to the front face region than the back face region of the blade. 
     The recovery gel  108  can be in the form of a memory shape gel such that it is shape recoverable. In this way, the recovery gel  108  offers some resistance to spreading across the surface of the core  110 . If pressure is applied to the recovery gel  108 , it can move and spread slightly. However, as soon as the pressure is removed, the recovery gel  108  will reform into its original shape. This allows the recovery gel  108  to remain uniform under the carbon skin during the use of the blade as impacts occur. This also allows the recovery gel to be configured to absorb energy impacts between the outer layer and the core of the blade. 
     The recovery gel can also be formed compressible, such that it can be pressurized to a predetermined pressure, which in one example can be up to 2 Bar. In this way, the recovery gel can be configured to provide an integrated agent for filling cracks that appear during use of the sporting implement. However, in other examples, the recovery gel can exhibit a very low pressure or no pressure at all. In one example, 5+/−1 grams of a recovery gel can be applied on each side of the core  110 . However, in other examples, the amount of recovery gel can range from 2 to 15 grams. 
     Also, in one example, the recovery gel can be visco-elastic, which means that with a high speed rate of stress, the behavior of the recovery gel is close to a stiffer material, similar to a plastic, while if the speed rate of stress is low, the behavior is closer to a fluid similar to water. Without stickiness or tackiness, the recovery gel may slide between the layers of the blade (carbon skins and core) and may not transmit the shear stresses resulting in a soft blade. 
     Various methods can be used to apply the recovery gel to the core. For example, the recovery gel can be brushed onto the core or brushed onto the prepreg or outer carbon layers. In other examples, the recovery gel can be brushed over a super-thin layer of glass fiber and then applied to the core or casted in a preform and applied to the core. Also, a thickness calibrated sheet of material or gel sheet can be formed, cut, sprayed or dipped with the recovery gel and then applied to the core. The sheet of material can remain on the structure or can be peeled away to act as a release layer. In certain examples, the release layer can be adhered to a piece of the prepreg that forms the outer layer, which then is wrapped around the core. In one example, the sheet of material can be die-cut to the desired shape such that the scrap rate is low and the efficiency is higher. In yet another example, the recovery gel may also be injected at the surface of the core with a syringe. 
     In certain examples, a suitable material for the recovery gel  108  can be polyurethane blended with expandable microspheres. This formulation helps to ensure the cohesion of the core material of a sandwich structure by integrating a material that will fill cracks and be sticky enough to transmit stresses. In some examples, the recovery material can be a blend of three different materials. For example, the recovery gel can be polyurethane, with a mix ratio of 1:5 by weight, microspheres from Expancel and a red dye gel containing no water solvent. Other example recovery gel materials may include silicone, epoxy, polyester, vinyl-ester, rubber, gelatin, hydrogels, organogels, xerogels, or combinations thereof. The recovery gel  108  can have the consistency of a paste and can have a hardness of 20 Shore 00 value once polymerized. 
     In certain examples, red dye can be used to monitor and visualize the material behavior of the recovery gel inside the blade after cutting it. The red dye also helps to determine the misplacement and the degree of curing. Additionally, the dye can appear as a “blood” color to showcase a “living technology” to the end user. Without the dye, it may be more difficult to see where the recovery gel went relative to the core. For example, the red dye helps to confirm that the recovery gel did exactly what was expected during the formation of a crack. For example, a technician may see several thin red lines within the epoxy core after several impacts indicating that the recovery gel really did flow within the crack to repair the failure within the core. 
     The core can then be wrapped with one or more carbon layers to form the outer layer  106  of the blade. For example, as illustrated in  FIG. 3 , the core  110  can be wrapped with a layer of carbon tape  140  that is optionally preimpregnated with resin, resulting in a wrapped structure  160 . The tape  140  can be, in one example, wrapped continuously around the first core face  132 , the second core face  134 , the top core edge  136  and the bottom core edge  138  of the core  110  and recovery gel  108 . This continuous wrapping of the core  110  with the tape  140  results in a first wrapped face  152 , a second wrapped face  154 , a top wrapped edge  156  and a bottom wrapped edge  158 . It is to be understood that a layer of tape or material need not consist of a single unitary piece or sheet of material. For example, a layer can consist of a combination of multiple pieces or sheets that overlap. 
     Once the foam core is wrapped with one or more layers of carbon tape  140 , a stitching or tufting process may also be used to avoid any post-expansion of the blade during the post-curing steps. In one implementation, the stitching may extend through or around recovery gel  108 . An example core and stitching process is described, for example, in U.S. Pat. No. 9,295,890, again, the entire contents of which are incorporated herein by reference for any and all non-limiting purposes. In one example, the thread (not shown) may be a high strength polyester thread that can withstand heating and maintain its physical properties at and above the temperature of the mold, which in one example can range from 135 to 165 degrees C. In other examples, the thread may also be a carbon fiber thread or a carbon fiber thread preimpregnated with resin. In certain examples, the thread can be stitched onto the tape  140  in a series of three parallel lines of stitching. In alternative examples (not shown), eight parallel lines of thread are used. In other examples, there is no set or predetermined pattern to the thread. 
     The stitching or tufting process may be applied to the core after one or more of the carbon layers are applied to the blade. In one example, the foam core  110  can be wrapped with a single layer of carbon tape  140  before the stitching or tufting operation. Wrapping the core  110  with too many layers of carbon tape prior to stitching may in certain instances result in wrinkling of the tape when it is stitched or tufted. The thread can extend from the first wrapped face  152  through the core  110  to the second wrapped face  154 . The thread creates the effect of an I-beam between the first wrapped face  152  and the second wrapped face  154  and adds structural and shear strength and rigidity between the faces. The thread can also pull the first wrapped face  152  and the second wrapped face  154  at the point where the thread enters the core  110 . Hence, in certain examples, the wrapped, stitched core is not flat in that the result of the thread pulling the tape  140  toward the core  110  and various locations creates a somewhat bumpy or pillow effect on the surface of the first wrapped face  152  and the second wrapped face  154 . However, after the application of the thread through stitching or tufting, one or more layers of carbon tape  140  can be added to the core resulting in a smooth preform. 
     It is also contemplated that a veil or scrim material (not shown) in the form of a thin non-tacky layer of woven fiberglass or polyester can be placed along the first wrapped face  152  and the second wrapped face  154  to allow for stitching or tufting without wrinkling the tape or causing the machinery to otherwise stick or jam. The veil is placed on the wrapped faces  152 ,  154  in the manner of a sandwich, with a single layer of material on each face. 
     Once the carbon layers are applied onto the blade, the blade can be molded separately or together with the shaft of the stick.  FIG. 3B  shows a schematic of a cross-section of the preform in a mold prior to the molding operation. As shown in  FIG. 3B , the blade construct can be placed into a mold  170 , which can consist of a first mold half  170 A and a second mold half  170 B, where heat is applied to the preform. In one example, the mold  170  can be formed of a suitable metal.  FIG. 3C  shows an enlarged view of the preform before the molding operation. 
     As shown in  FIG. 4A , heat is applied to the mold and during the molding operation, the epoxy core  110  takes expansion and pushes the recovery gel  108  and the carbon layers  106  against the mold walls, as indicated by the arrows in  FIG. 4A . In one example, and as discussed herein, the carbon layers  106  can be impregnated with an epoxy resin. The epoxy resin makes the carbon layers  106  somewhat impermeable to the recovery gel  108 . Thus, in certain examples, where the recovery gel  108  is a shape recovery gel, the recovery gel  108  can be compressed and be pressurized to a predetermined pressure, which in one example can be up to 2 Bar. Also during the curing of the blade, the resin impregnated in the carbon layers or plies  106  crosslinks and becomes hard, and the epoxy in the epoxy core  110  also crosslinks and becomes hard. After curing, the recovery gel  108  becomes entrapped and pressurized between the core  110  and the carbon layers  106 , which shown is in the enlarged schematic of the construct in  FIG. 4B . However, the pressure of the recovery gel  108  is not high enough to deform the blade when the stick is taken out of the mold due to the stiffness of the carbon fibers. Nonetheless, the pressure of the recovery gel  108  is sufficient to fill any cracks when they appear in the core or the outer layer, e.g. carbon layers  106 . 
     During use of the blade, the recovery gel  108  also creates a soft “feel” or interface between the epoxy core  110  and the carbon layer or skin  106  that receives impacts, helping to prevent the epoxy core  110  from cracking easily due to its relative brittleness. Moreover, in using a film, the carbon skins  106  can be limited in their movement and are less likely to fail by overpassing their maximum strain. The recovery gel  108  allows the outer layer  106  to deflect a limited amount to help prevent the outer layer  106  from tearing or breaking, which could occur with a fully soft core. In one example, the deflection or movement of the carbon layer  106  is limited to 0.5-1 mm. 
     Referring now to  FIGS. 5A-5C  if the core  110  or the outer layer  106  at the recovery gel interface cracks due to a large deformation or impact, the predetermined pressure of the recovery gel is relieved into the cracks or cavities formed by the cracks and fills into the cracks or cavity of the core. Specifically, as a crack  172  is formed in the core  110 , the pressurized recovery gel  108  flows into the crack  172  as shown by the downward pointing arrow in  FIG. 5B . As shown in  FIG. 5C , this can provide cohesion between separated components, i.e., the outer carbon layer and the core and can recreate a new material in the place of the cracks or cavities. In essence, the recovery gel  108  recreates a new foam material where voids were created in the core  110 . This allows the recovery gel  108  to help prevent cracks from propagating and to actively heal potential damages by reducing stiffness loss caused by cracks. 
     In certain examples, the tackiness of the recovery gel  108  can be high, meaning that there are a lot of molecular functions available. For example, the recovery gel surface in contact with the core is very high allowing it to flow into small cracks or holes. Moreover, the recovery gel itself can include some weak links as a result of its formulation and, thus, would “prefer” to adhere with other structures, similar to polar molecules of a degreasing agent. This allows the recovery gel  108  to adhere to any cracks and, thus, creates a new bond between each side of the crack. Also, where expandable microspheres are used in the recovery gel, the expandable microspheres are useful in filling any major cracks when they occur. 
     Additionally, if it becomes apparent that a crack has formed in the blade meaning the core is broken, for example, if the user hears a sound during use of the blade, the stick can be placed into an oven at 135° C. for 3 to 5 minutes. This can be useful in instances where it is apparent that the recovery gel has not filled the space of the crack formed in the blade or where the entire pressure of the recovery gel has already been relieved by a large amount of cracks in the core. The heat applied to the blade can in certain examples allow the recovery gel to expand and fill in any major cracks in the core. The tackiness of the gel after curing the blade in the oven may be slightly lower but will still be present should additional cracks form in the core. In addition, when the recovery gel  108  cures in a crack, the texture of the recovery gel changes to be more consistent with the texture of a foam material so that the feel of the sporting implement or hockey stick does not change significantly. The expandable microspheres inside the gel can expand as the gel fills into cracks in the core. The cracks create room for the gas in the expandable microspheres to expand. As the gel expands, the density can become lower (same weight but bigger volume). The overall material of the blade can feel and behave more like a foam material than the previous form of the recovery gel because the gas of the expanded microspheres is released resulting in a material closer to foam. However, the properties of the recovery gel remaining between the core and the outer layer will not change significantly including its texture. 
     The hockey stick  100  may additionally include a dilatant material that exhibits differing material properties depending on the type of maneuver being performed with the stick  100 . Advantageously, the dilatant material may offer a player a desirable combination of a softer feeling blade  104  when executing low-impact maneuvers with a puck, such as stick handling, and a harder feeling blade  104  when executing high-impact maneuvers, such as a slap shot. 
     In particular, a dilatant material, otherwise referred to as a shear-thickening material and/or a non-Newtonian fluid, may exhibit increasing viscosity with increasing rate of shear strain. Accordingly, the blade  104  may include a dilatant material that may exhibit a first, comparatively low viscosity when the blade  104  is subjected to a comparatively low impact by a puck, such as when a player is stick handling, or executing a wrist shot, among others. Conversely, the dilatant material may exhibit a second, comparatively higher viscosity when the blade  104  is subjected to a comparatively high impact by a puck, such as when a player is executing a slap shot, among others. Accordingly, the dilatant material may be designed to exhibit a first viscosity when the outer layer  140  of the blade  104  is subjected to an impact force below a threshold force level, and a second viscosity, higher than the first viscosity, when the outer layer  140  of the blade  104  is subjected to an impact force above the threshold force level. It is contemplated that this threshold force level may be implemented with any value, without departing from the scope of these disclosures. 
     In one example, the blade  104  of the hockey stick  100  may include one or more dilatant materials made from polyethylene glycol that may be formed in combination with silica particles. Further, the dilatant material may be in the form of a deformable gel that is mixed with one or more polymers to form a composite material. In one specific example, the polymer may be a polyurethane, or a combination of polyurethane and expandable microspheres. As such, the expandable microspheres may be similar to those described in U.S. Pat. No. 9,802,369, filed 14 Mar. 2008, the entire contents of which are incorporated herein by reference in their entirety for any and all non-limiting purposes. However, additional or alternative dilatant materials may be used with the various implementations described throughout this disclosure. 
     In one example, the core  110  of blade  104  may be formed of a dilatant material or composite of a dilatant material and polymer, as described above. In another example, a dilatant material may be included in the recovery gel  108 . Additionally, a dilatant material may form a layer  162  that partially or wholly surrounds the core  110 . This implementation is schematically depicted in  FIG. 8 , which includes several elements described in relation to  FIG. 3A , in addition to the dilatant material layer  162 . In another example, a dilatant material may form a layer  162  that partially or wholly surrounds the recovery gel  108 . This implementation is schematically depicted in  FIG. 9 , which includes several elements described in relation to  FIG. 3A , in addition to the dilatant material layer  162 . 
     In one example, the dilatant material layer  162  depicted in  FIGS. 8 and 9  may be encapsulated within a deformable pocket. This pocket may be formed from any suitable polymer, and may have any size and geometry, without departing from the scope of these disclosures. Alternatively, the dilatant material layer  162  depicted in  FIGS. 8 and 9  may be implemented as a gel, or solid material that is applied directly to the blade  104  without additional encapsulation. 
     In another implementation, a dilatant material, similar to the dilatant material layer  162 , may be used within one or more portions of a hockey stick shaft  102 . As such, the dilatant material may exhibit a variable hardness when a player is gripping the hockey stick shaft  102  under differing circumstances. Advantageously, the use of a dilatant material  162  within one or more portions of a hockey stick shaft  102  may improve inter-laminar shear performance of the shaft material. 
     It is further contemplated that a dilatant material may be used at any of the locations previously discussed in relation to the recovery gel  108 , and may be used in addition to, or as an alternative to the recovery gel  108  may, without departing from the scope of these disclosures. For example, a dilatant material may be integrated into a hockey stick core  110  with geometries similar to those described in relation to the recovery gel  108  in  FIGS. 6A-6C . 
       FIG. 10  schematically depicts a hockey stick blade  1000  that may include a dilatant material and a recovery gel, according to one or more aspects described herein. In particular,  FIG. 10  schematically depicts an internal view of the hockey stick blade  1000  with an outer surface of the blade removed. As such, in one example, area  1002  may include a dilatant material, as previously described. Further, area  1004  may include a recovery gel, as previously described in relation to recovery gel  108 . In another example, area  1002  may include a combination of a dilatant material and a recovery gel, and area  1004  may include a foam core. 
       FIG. 11  schematically depicts another example implementation of a hockey stick blade  1100 . The hockey blade  1100  is shown having a toe region  1106 , a middle region  1108  and a heel  1110 . A core  1102  of the hockey blade  1100  can be formed of a first lower density foam core portion  1102 A and a second higher density foam core portion  1102 B. The first core portion  1102 A can be stitched using a thread  1112 . The second core portion  1102 B can be formed of an epoxy having a plurality of polymeric shell microspheres. Additionally or alternatively, the second core portion  1102 B may include a dilatant material, as previously described to read these disclosures. The first core portion  1102 A and the second core portion  1102 B are bonded to form the continuous core  1102 . In particular, the first core portion  1102 A has a bottom surface  1104 A which is bonded to a top surface  1104 B of the second core portion  1102 B during a molding and cross-linking process. 
     The first core portion  1102 A extends from the heel  1110  of the blade to the toe region  1106  of the blade. The first core portion  1102 A can be formed thickest at the heel  1110  of the blade and can taper from the heel  1110  of the blade to the toe region  1106  of the blade. Forming the first core portion  11102 A thickest or widest in the heel  1110  compensates for the loss of stiffness due to the lower density and lower modulus of the foam. The second core portion  1102 B extends from the toe region  1106  of the blade to the heel  1110  of the blade  1100 . The second core portion can be thickest at the toe region  1106  of the blade  1100  and can taper from the toe region  1106  of the blade  1100  to the heel  1110  of the blade  1100 . Both the first core portion  1102 A and the second core portion  1102 B can extend all the way to the toe edge  1114  of the blade  1100 . It is understood, however, that other arrangements and ratios of the core portions  1102 A,  1102 B can be formed to accomplish different stick characteristics, weights, and strengths. For example, the core portions can be formed in different arrangements as shown in  FIGS. 12 and 13 , the description of which follows. 
       FIG. 12  shows an alternative arrangement. The blade  1200  comprises a first core portion  1202 A and second core portion  1202 B, which makes up the core  1202 . In one example, the second core portion  1202 B may include a dilatant material. The arrangement is similar to the arrangement in  FIG. 11  with the exception that the first core portion  1202 A does not extend as far down the blade  1200 . In addition, the joint  1216  between the first core portion  1202 A and the second core portion  1202 B forms a straighter line. The straight line joint  1216  is advantageous as it may reduce the overall stress on the blade during use. 
     Another alternative arrangement is shown in  FIG. 13 . The embodiment shown in  FIG. 13  is similar to the embodiments shown in  FIGS. 11 and 12 . However, the core  1302  of the blade  1300  has first and second core portions  1302 A and  1302 B that are formed with an oval-like shape at one end and a hook shape at the other end to receive the respective oval-like shaped ends. In one example, the second core portion  1302 B may include a dilatant material. If one of the core portions  1302 A or  1302 B is formed with an epoxy, this arrangement and shaping of the first and second core portions  1302 A and  1302 B allows for the epoxy to flow and fill more evenly in the formation process. 
     In other examples, the core of the blade can be manufactured by forming a construct of multiple cores or foams. Different combinations of core materials are used to create distinct recipes of core mixtures. The different mixtures can be used to create a blade with zones of varying density and stiffness. Core mixtures with higher density materials can be placed in the areas of the blade subject to greater forces and impacts, such as the bottom or heel, to create stronger blade regions. For instance, the bottom of the blade and the heel of the blade are typically subject to the most force and impact from striking the ice or a hockey puck. For example, the different cores can be placed on various locations of the blade to create a blade with zones of varying density, such as the top or the toe of the blade to reduce weight. Higher density foam can be placed along the bottom of the blade where the blade is subjected to high impacts and lower density foam can be placed at an upper portion of the blade where the blade is subject to fewer impacts. One such example core is discussed in U.S. Pat. No. 9,289,662, the entire contents of which are incorporated herein by reference for any and all non-limiting purposes. Where different cores or foams are used the core could be provided with more than one type of recovery gel such that each core or foam is provided with a specific recovery gel that is most suitable for filing cracks that form in the particular core or foam. For example, recovery gels could be placed inside carbon compartments to divide the recovery gels across the blade. Also, the recovery gels could potentially have a different absorption or feel across the length of the blade to provide different properties when cracks form. 
     An example process of manufacturing a blade in accordance with the disclosure is illustrated in  FIG. 6 . First a foam core is formed as shown at step  202 . Next a recovery gel can be added to the foam core at  204  such that it is applied to each face of the core or such that the recovery gel extends around the foam core entirely. For example, multiple sheets of material containing the recovery gel can be formed, weighed, and cut. The sheets of material, which can be small inserts or parts, are then adhered on the desired portions of the core. In other examples, as discussed above, the recovery gel can be brushed onto the core, brushed onto the outer layer, or injected. In other examples, the recovery gel can be brushed over a super-thin layer of glass fiber and then applied to the core or casted in a preform and applied to the core. 
     The foam core is then wrapped with a first layer or layers of carbon or fiber tape as shown at  206 . The first layer of carbon or fiber tape extends continuously along the first core face, top core edge, second core face and bottom core edge of the foam core, such that the wrapped core has a first wrapped face, a second wrapped face, a top wrapped edge and a bottom wrapped edge. Optionally, a non-sticky veil can be applied to the first wrapped face and second wrapped face to assist with a stitching or tufting process. The wrapped foam core can then be stitched or tufted with a thread as shown at  208 . The thread extends between and along the first wrapped face and the second wrapped face. The stitched wrapped core may be wrapped with a second layer or layers of fiber tape to form a wrapped preform, as shown at  210 . The second layer of fiber tape extends continuously atop the first layer of fiber tape and along the first wrapped face, the top wrapped edge, the second wrapped face, and the bottom wrapped edge. 
     The wrapped preform is then placed in a mold, as shown at  212 , and the mold is heated to an appropriate temperature. In one example, the mold is heated to between 135 to 165 degrees C., and in one particular example, the mold can be heated to 160 degrees C. The heating causes the recovery gel to become pressurized between the core and the layers of fiber tape. The resin in the preimpregnated tape melts, flows through the woven veil, if used, crosslinks and bonds the layers of fiber tape together. When the recovery gel is applied it can be placed to avoid direct contact between the layers of carbon and the core. When recovery gel inserts are used, contact between the layers of carbon and the core is avoided in the location of the insert but the remainder of the layers of carbon and the core of the blade are in direct contact. However, if the core is entirely covered with the recovery gel around the core, no bonding will occur between the epoxy core and the carbon prepreg layers. In one example, the recovery gel that is applied to the core before molding can be already polymerized at 100% and, thus, during formation does not crosslink to the layers of carbon and core. 
     Additionally, when the mold is heated, the resin in the preimpregnated tape can flow along the threads and into the core. When this resin cools, it creates additional strength in the z-axis of the structure. Carbon fiber thread, which may be used in one example, shrinks when it is heated. Carbon fiber thread results in a more homogenous structure because the carbon fiber thread shares properties with the carbon fiber tape. The thread can also create a stiffening agent that gives additional resistance against shearing. The mold is then cooled, and the formed structure is removed from the mold. 
     It is also contemplated that the blade could be formed using a resin transfer molding (RTM) process. In such a case, the recovery gel can be encapsulated between the core and the outer layer. However, the recovery gel would not be configured to flow into a crack or tear in the core during use of the blade. Nevertheless, if a crack is formed in the core of an RTM formed blade, heating the blade will force the microspheres to expand and, thus, fill the crack. Therefore, a blade formed by RTM can be configured to be healable by heating the core or by “thermal-healing” the core. 
     In one example, a sporting implement can include a recovery gel, which can be a memory shape gel. The recovery gel can form a film within the sporting implement. The recovery gel can be compressible, shape recoverable, and pressurized to a predetermined pressure so as to provide an integrated agent for filling cracks that appear during use of the sporting implement. The sporting implement may include an outer layer and a core, and the recovery gel can be configured to absorb energy impacts between the outer layer and the core. The core can be formed of an epoxy, and the outer layer may include a carbon skin to form a blade for a hockey stick. The recovery gel may allow the outer layer to deflect no more than 0.5 to 1 mm and to help prevent the outer layer from tearing or breaking. When a crack appears, the predetermined pressure can be relieved inside the crack and fill a cavity formed by the crack to provide cohesion between separated components to recreate a new material in the place of the crack. In one example, the predetermined pressure can be 0 to 2 Bar. The recovery gel can be configured to help prevent cracks from propagating and actively heals potential damages by reducing stiffness loss caused by cracks. The recovery gel can include a polyurethane blended with expandable microspheres. 
     In another example, a blade for a hockey stick may include an outer layer, a core, and a recovery gel positioned between the core and the outer layer. The recovery gel can form a film, and the recovery gel can be compressible, shape recoverable, and pressurized to a predetermined pressure and configured to provide an integrated agent for filling cracks that appear during use of the blade. The recovery gel can be configured to absorb energy impacts between the outer layer and the core. The recovery gel can partially cover a surface of the core, or alternatively, the recovery gel can cover an entire surface of the core. 
     Also the core can be formed of an epoxy, and the outer layer may include a carbon skin. The recovery gel can allow the outer layer to deflect no more than 0.5 to 1 mm and to help prevent the outer layer from tearing or breaking. When a crack appears, the predetermined pressure can be relieved inside the crack and fills a cavity formed by the crack to provide a cohesion between the outer layer and the core to recreate a new material in the place of the crack. In one example, the predetermined pressure is 0 to 2 Bar. The recovery gel can be configured to help prevent cracks from propagating and actively heals potential damages by reducing stiffness loss caused by cracks. The recovery gel can include a polyurethane blended with expandable microspheres. 
     In yet another example, a method of actively healing a blade for a hockey stick may include forming an outer layer, forming a core, and placing a recovery gel between the core and the outer layer. In one example, the recovery gel can form a film. The method may also include configuring the recovery gel to be compressible, and shape recoverable and pressurizing the recovery gel to a predetermined pressure to provide an integrated agent for filling cracks that appear during use of the blade. The method may also include configuring the recovery gel to absorb energy impacts between the outer layer and the core, forming the core of an epoxy and forming the outer layer of a carbon skin and configuring the recovery gel to allow the outer layer to deflect no more than 0.5 to 1 mm and to help prevent the outer layer from tearing or breaking. Additionally the method may include configuring the predetermined pressure of recovery gel to be relieved inside a crack to fill a cavity formed by the crack to provide a cohesion between the outer layer and the core to recreate a new material in the place of the crack, setting the predetermined pressure to 0 to 2 Bar, configuring the recovery gel to help prevent cracks from propagating and to actively heal potential damages by reducing stiffness loss caused by cracks, forming the recovery gel of a polyurethane blended with expandable microspheres, and heating the blade at 135° C. for 3 to 5 minutes to help fill cracks. 
     In one implementation, a blade for a hockey stick may include an outer layer, core, and a dilatant material positioned between the core and the outer layer, with the dilatant material forming a film. The dilatant material may be configured to exhibit a first viscosity when the outer layer of the blade is subjected to an impact force below a threshold level. The dilatant material may be configured to exhibit a second viscosity, higher than the first viscosity, when the outer layer of the blade is subjected to an impact force above the threshold level. 
     In one example, a dilatant material may be encapsulated within a deformable pocket between an outer layer and a core of a hockey stick blade. 
     In another example, a dilatant material may be combined with a polymer to form a composite material. The polymer may be a polyurethane, or a mixture of polyurethane and expandable microspheres. 
     A dilatant material used in a blade of a hockey stick may include a polyethylene glycol in combination with silica particles. 
     A core of a hockey stick blade may be formed of an epoxy and an outer layer of a hockey stick blade may be formed of a carbon skin. 
     A blade of a hockey stick may additionally include a recovery gel positioned between a core and a dilatant material, such that the recovery gel may be compressible, shape recoverable, and pressurized to a predetermined pressure. The recovery gel may be configured to provide an integrated agent for filling cracks that may appear during use of the blade. 
     A blade of a hockey stick may additionally include a recovery gel formed as a mixture with a dilatant material, such that the mixture has dilatant material properties and material properties of a recovery gel. 
     In another implementation, a blade for a hockey stick may include a core that includes a dilatant material, and an outer layer that includes a carbon skin extending around the core. The dilatant material may be configured to exhibit a first viscosity when the outer layer of the blade is subjected to an impact force below a threshold level. The dilatant material may be configured to exhibit a second viscosity, higher than the first viscosity, when the outer layer of the blade is subjected to an impact force above the threshold level. 
     In one example, the dilatant material may allow the outer layer of the hockey stick blade to deflect by no more than 0.5 to 1 mm to prevent the outer layer from tearing or breaking. 
     In another example, a dilatant material may be combined with a polymer to form a composite material. The polymer may be a polyurethane, or a mixture of polyurethane and expandable microspheres. 
     In one example, a dilatant material used in a blade of a hockey stick may include a polyethylene glycol in combination with silica particles. 
     A blade of a hockey stick may additionally include a recovery gel positioned between a core and an outer layer of the blade, such that the recovery gel may be compressible, shape recoverable, and pressurized to a predetermined pressure. The recovery gel may be configured to provide an integrated agent for filling cracks that may appear during use of the blade. 
     A blade of a hockey stick may additionally include a recovery gel formed as a mixture with a dilatant material, such that the mixture has dilatant material properties and material properties of a recovery gel. 
     In another implementation, a sporting implement may include a dilatant material that is configured to exhibit a first viscosity when the outer layer of the sporting implement is subjected to an impact force below a threshold level. The dilatant material may be configured to exhibit a second viscosity, higher than the first viscosity, when the outer layer of the sporting implement is subjected to an impact force above the threshold level. 
     In another example, a dilatant material may be combined with a polymer to form a composite material. The polymer may be a polyurethane, or a mixture of polyurethane and expandable microspheres. 
     A dilatant material used in a sporting implement may include a polyethylene glycol in combination with silica particles. 
     A sporting implement may additionally include a recovery gel that forms a film and is compressible, shape recoverable, and pressurized to a predetermined pressure. The recovery gel may be configured to provide an integrated agent for filling cracks that may appear during use of the sporting implement. 
     A recovery gel used in a sporting implement may be mixed with a dilatant material. 
     In one example, an outer layer of a sporting implement formed of a carbon skin may encapsulate a dilatant materials. 
     The reader should understand that these specific examples are set forth merely to illustrate examples of the disclosure, and they should not be construed as limiting this disclosure. Many variations in the connection system may be made from the specific structures described above without departing from this disclosure. 
     While the invention has been described in detail in terms of specific examples including presently preferred modes of carrying out the invention, those skilled in the art will appreciate that there are numerous variations and permutations of the above described systems and methods. Thus, the spirit and scope of the invention should be construed broadly as set forth in the appended claims.