Patent Publication Number: US-2005142967-A1

Title: Vibration dampening material and method of making same

Description:
CROSS REFERENCE TO RELATED APPLICATIONS  
      This application is a continuation-in-part of U.S. Patent Application, currently pending, which is a continuation of and claims priority to U.S. patent application Ser. No. 10/659,560, currently pending, which is a divisional of and claims priority to U.S. patent application Ser. No. 09/939,319, filed on Aug. 27, 2001, now U.S. Pat. No. 6,652,398; priority to each of the above identified applications is claimed and each of the above identified applications are hereby incorporated by reference herein as if fully set forth in their entirety. 
    
    
     BACKGROUND  
      The present invention is directed to a material adapted to reduce vibration and, more specifically, to a method of making a material adapted to dissipate and evenly distribute vibrations acting on the material.  
      Handles of sporting equipment, bicycles, hand tools, etc. are often made of wood, metal or polymer that transmit vibrations that can make the items uncomfortable for prolonged gripping. Sporting equipment, such as bats, balls, shoe insoles and sidewalls, also transmit vibrations during the impact that commonly occurs during athletic contests. These vibrations can be problematic in that they can potentially distract the player&#39;s attention, adversely effect performance, and/or injure a portion of a player&#39;s body.  
      Rigid polymer materials are typically used to provide grips for tools and sports equipment. The use of rigid polymers allows users to maintain control of the equipment but is not very effective at reducing vibrations. While it is known that softer materials provide better vibration regulation characteristics, such materials do not have the necessary rigidity for incorporation into sporting equipment, hand tools, shoes or the like. This lack of rigidity allows unintended movement of the equipment encased by the soft material relative to a user&#39;s hand or body.  
      Prolonged or repetitive contact with excessive vibrations can injure a person. The desire to avoid such injury can result in reduced athletic performance and decreased efficiency when working with tools.  
      Clearly what is needed is a method of making a material adapted to regulate vibration that provides the necessary rigidity for effective vibration distribution and for a user to maintain the necessary control of the implement; that can dampen and reduce vibrational energy; and that includes a support structure that is embedded on and/or within a main vibration dissipating material.  
     SUMMARY  
      One embodiment of the present invention is directed to a material adapted to regulate vibration by distributing and partially dissipating vibration exerted thereon. The material includes an elastomer layer. A support structure is penetrated by and embedded on and/or within the elastomer layer. The support structure is semi-rigid and supports the elastomer layer.  
      In another aspect, the present invention is directed to a method of making a material adapted to regulate vibration. The method includes: providing an uncured elastomer; positioning a cloth layer formed by plurality of woven aramid fibers on and/or within the uncured elastomer, the uncured elastomer penetrates the cloth layer to embed the cloth layer; and at least partially curing the uncured elastomer to form the material, the cloth layer supporting the cured elastomer and facilitating the distribution and dissipation of vibration by the material.  
      In another aspect, the present invention is directed to a method of making a grip for an implement having a handle and a proximal end. The grip is formed by a single material adapted to regulate vibration. The method includes: providing an uncured elastomer; positioning a plurality of fibers within the uncured elastomer; at least partially curing the uncured elastomer to form the single layer material embedding the plurality of fibers therein, the single layer material having * first and second major material surfaces; and positioning the single layer material over at least a portion of the handle and over the proximal end of the handle, the first major material surface contacting the implement and the second major material surface of the single layer material forming a surface for a user to grasp.  
      In another aspect, the present invention is directed to a method of making a material adapted to regulate vibration. The method includes: providing a cloth formed by a plurality of woven aramid fibers, the cloth having first and second major surfaces; placing a first elastomer layer on the first major surface of the cloth; and placing a second elastomer layer on the second major surface of the cloth, the first and second elastomer layers penetrating the cloth to form a single layer elastomer having an embedded cloth for support thereof.  
      In another aspect, the present invention is directed to a method of forming a material adapted to regulate vibrations. The method includes: providing a cloth layer; positioning an elastomer substantially over the cloth layer; and applying pressure to the cloth layer and the elastomer to embed the cloth layer to form the material.  
      In another aspect, the present invention is directed to material adapted to regulate vibration by distributing and partially dissipating vibration exerted thereon. The material includes a polymer layer. A support structure is penetrated by an embedded on and/or within the polymer layer. The support structure is semi-rigid and supports the polymer layer. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      The foregoing summary, as well as the following detailed description of the preferred embodiments of the present invention will be better understood when read in conjunction with the appended drawings. For the purpose of illustrating the invention, there are shown in the drawings embodiments which are presently preferred. It is understood, however, that the invention is not limited to the precise arrangements and instrumentality shown. In the drawings:  
       FIG. 1  is a cross-sectional view of a preferred embodiment of the material of the present invention illustrating a single layer vibration dissipating material with a support structure embedded therein, the material extends along a longitudinal portion of an implement and covers a proximal end thereof;  
       FIG. 2  is a cross-sectional view of the material of  FIG. 1  separate from any implement, padding, equipment or the like;  
       FIG. 2A  is a cross-sectional view of a second preferred embodiment of the material of the present invention with the support structure embedded thereon and the vibration dissipating material penetrating the support structure;  
       FIG. 2B  is cross-sectional view of a third preferred embodiment of the material of the present invention with the support structure embedded within the vibration dissipating material and the vibration dissipating material penetrating the support structure, the support structure is positioned off center within the vibration dissipating material;  
       FIG. 3  is a cross-sectional view of a first preferred embodiment of the support structure as taken along the lines  3 - 3  of  FIG. 2 , the support structure is formed of polymer and/or elastomer and/or fibers, either of which may contain fibers, passageways extend through the support structure allowing the vibration dissipating material to penetrate the support structure;  
       FIG. 4  is cross-sectional view of a second preferred embodiment of the support structure as viewed in a manner similar to that of  FIG. 3  illustrating a support structure formed by woven fibers, passageways through the woven fibers allow the support structure to be penetrated by the vibration dissipating material;  
       FIG. 5  is cross-sectional view of a third preferred support structure as viewed in a manner similar to that of  FIG. 3 , the support structure formed by plurality of fibers, passageways past the fibers allow the vibration dissipating material to penetrate the support structure;  
       FIG. 6  is a side elevational view of the support structure of  FIG. 3 ;  
       FIG. 7  is perspective view of the material of  FIG. 1  configured to form a grip for a bat; and  
       FIG. 8  is perspective view of the material of  FIG. 1  configured to form a grip for a racquet.  
       FIG. 9  is an elevational view of a baseball bat having a cover in the form of a sleeve on the handle area in accordance with this invention;  
       FIG. 10  is an enlarged fragmental cross-sectional view of the bat and sleeve shown in  FIG. 9 ;  
       FIG. 11  is a schematic diagram showing the results in the application of shock forces on a cover in accordance with this invention;  
       FIG. 12  is a view similar to  FIG. 10  showing an alternative sleeve mounted on a different implement;  
       FIG. 13  is a view similar to  FIGS. 10 and 12  showing still yet another form of sleeve in accordance with this invention;  FIG. 14  is a cross-sectional longitudinal view showing an alternative cover in accordance with this invention mounted on a further type of implement;  
       FIG. 14  is a cross-sectional longitudinal view showing an alternative cover in accordance with this invention mounted on a further type of implement;  
       FIG. 15  is a cross-sectional end view of yet another cover in accordance with this invention;  
       FIG. 16  is an elevational view of a hammer incorporating an abrasive dampening handle in accordance with this invention;  FIG. 17  is an elevational view showing a portion of a handlebar incorporating a vibration dampening cover in accordance with this invention;  
       FIG. 17  is an elevational view showing a portion of a handlebar incorporating a vibration dampening cover in accordance with this invention;  
       FIG. 18  is a view similar to  FIG. 17  of yet another practice of this invention; and  
       FIGS. 19-22  are plan views of various forms of the intermediate force dissipating layer which is used in certain practices of this invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
      Certain terminology is used in the following description for convenience only and is not limiting. The words “right,” “left,” “top,” and “bottom” designate directions in the drawings to which reference is made. The words “inwardly” and “outwardly” refer to directions toward and away from, respectively, the geometric center of the material and designated parts thereof. The term “implement,” as used in the specification and in the claims, means “any one of a baseball bat, racquet, hockey stick, softball bat, sporting equipment, firearm, or the like.” The above terminology includes the words above specifically mentioned, derivatives thereof, and words of similar import. Additionally, the words “a” and “one” are defined as including one or more of the referenced item unless specifically stated otherwise.  
      Referring to  FIGS. 1-8 , wherein like numerals indicate like elements throughout, there are shown preferred embodiments of a material, generally designated  10 , that is adapted to regulate vibration. Briefly stated, the material  10  preferably includes a vibration dissipating material  12  (preferably an elastomer layer). The vibration dissipating material  12  penetrates a support structure  17  to embed the support structure  17  thereon (as shown in  FIG. 2A ) and/or therein (as shown in  FIG. 2B ). The support structure  17  is preferably semi-rigid and supports the vibration dissipating material  12 .  
      The material  10  of the present invention was the result of extensive research and was thoroughly tested by Villanova University&#39;s Department of Mechanical Engineering by a professor having a Ph.D. in vibratory physics. Testing of the material  10  determined that the material  10  can reduce the magnitude of sensible vibration by eighty (80%) percent. The material  10  has verified, superior vibration dissipation properties due to the embedded support structure  17  that is located on and/or in the elastomer  12 . In addition to evenly distributing vibration, the support structure  17  contributes to the absorption of vibration and supports the vibration dissipating material  12  to prevent the layer of vibration dissipating material  12  from twisting or otherwise becoming unsuitable for use as a grip or padding.  
      While it is preferred that the vibration dissipating material layer  12  be formed by elastomer, those of ordinary skill in the art will appreciate from this disclosure that the vibration dissipating material  12  can be formed by any suitable polymer without departing from the scope of the present invention. For clarity only, the vibration dissipating material  12  will be often described herein as being an elastomer without any mention of the material possibly being a polymer. However, it should understood that even when the layer  12  is only described as being an elastomer, that the present invention also includes the material  12  being a any suitable polymer.  
      The material  10  of the present invention can be incorporated into athletic gear, grips for sports equipment, grips for tools, and protective athletic gear. More specifically, the material  10  can be used: to form grips for a tennis racquet, hockey sticks, golf clubs, baseball bats or the like; to form protective athletic gear for mitts, headbands, mouth guards, face protection devices, helmets, gloves, pads, hip pads, shoulder pads, chest protectors, or the like; to form seats or handle bar covers for bicycles, motorcycles, or the like; to form boots for skiing, roller blading or the like; to form footwear, such as shoe soles and inserts; to form grips for firearms, hand guns, rifles, shotguns, or the like; and to form grips for tools such as hammers, drills, circular saws, chisels or the like.  
      The elastomer layer  12  acts as a shock absorber by converting mechanical vibrational energy into heat energy. The embedded support structure  17  redirects vibrational energy and provides increased stiffness to the material  10  to facilitate a user&#39;s ability to control an implement  20  encased, or partially encased, by the material  10 . The incorporation of the support structure  17  on and/or within the material  10  allows the material  10  to be formed by a single elastomer layer without the material  10  being unsuitable for at least some of the above-mentioned uses. However, those of ordinary skill in the art will appreciate from this disclosure that additional layers of material can be added to any of the embodiments of the present invention disclosed below without departing from the scope of the invention.  
      It is preferred that the material  10  have a single contiguous elastomer body  12 . Referring to  FIG. 1 , the support structure has first and second major surfaces  23 ,  25 . In one embodiment, the elastomer  12  extends through the support structure  17  so that the portion of the elastomer  12 A contacting the first major support structure surface  23  (i.e., the top of the support structure  17 ) and the portion of the elastomer  12 B contacting the second major support structure surface  25  (i.e., the bottom of the support structure) form the single contiguous elastomer body  12 . Elastomer material provides vibration damping by dissipating vibrational energy. Suitable elastomer materials include, but are not limited, urethane rubbers, silicone rubbers, nitrile rubbers, butyl rubbers, acrylic rubbers, natural rubbers, styrene-butadiene rubbers, and the like. In general, any suitable elastomer or polymer material can be used to form the vibration dissipating layer  12 .  
      The softness of elastomer materials can be quantified using Shore A durometer ratings. Generally speaking, the lower the durometer rating, the softer the material and the more effective a material layer is at absorbing and dissipating vibration because less force is channeled through the material. When a soft material is squeezed, an individual&#39;s fingers are imbedded in the material which increases the surface area of contact between the user&#39;s hand and creates irregularities in the outer material surface to allow a user to firmly grasp any implement  20  covered, or partially covered, by the material. However, the softer the material, the less control a user has when manipulating an implement  20  covered by the material. If the elastomer layer is too soft (i.e., if the elastomer layer has too low of a Shore A Durometer rating), then the implement  20  may rotate unintentionally relative to a user&#39;s hand or foot. The material  10  of the present invention is preferably designed a Shore A durometer rating that provides an optimum balance between allowing a user to precisely manipulate and control the implement  20  and effectively damping vibration during use of the implement  20  depending on the activity engaged in.  
      It is preferable, but not necessary, that the elastomer used with the material  10  have a Shore A durometer of between approximately ten (10) and approximately eighty (80). It is more preferred that the elastomer  12  have a Shore A durometer of between approximately fifteen (15) and approximately forty-five (45).  
      The elastomer  12  is preferably used to absorb vibrational energy and to convert vibrational energy into heat energy. The elastomer  12  also provides a compliant and comfortable grip for a user to grasp (or provides a surface for a portion of a user&#39;s body, such as the under sole of a user&#39;s foot when the material  10  is formed as a shoe insert).  
      In one embodiment, the material  10  preferably has a Shore A durometer of approximately fifteen (15). In another embodiment, the material  10  preferably has a Shore A Shore Durometer of approximately forty two (42). In yet another embodiment, the material  10  preferably has a Shore A Durometer of approximately thirty-two (32). Of course, those of ordinary skill in the art will appreciate that the Shore A Durometer of the material  10  can varied without departing from the scope of the present invention.  
      Referring to  FIGS. 3-5 , the support structure  17  can be any one (or combination of) of a polymer, an elastomer, a plurality of fibers, a plurality of woven fibers, and a cloth. If the support structure  17  and the layer  12  are both polymers or both elastomers, then they can be the same or different from each other without departing from the scope of the present invention. If vibration dissipating material is  12  if formed of the same material as the support structure  17 , then the support structure  17  can be made more rigid than the main layer  12  by embedding fibers  14  therein. It is preferable that the support structure  17  is generally more rigid than the vibration dissipating material  12 .  
      Referring specifically to  FIG. 3 , the support structure  17  may be formed of an elastomer that may but does not necessarily, also have fibers  14  embedded therein (examplary woven fibers are shown throughout portions of  FIG. 3 ). Referring to  FIG. 4 , the support structure  17  may be formed by a plurality of woven fibers  18 . Referring to  FIG. 5 , the support structure  17  may be formed by a plurality of fibers  14 . Regardless of the material forming the support structure  17 , it is preferable that passageways  19  extend into the support structure  17  to allow the elastomer  12  to penetrate and embed the support structure  17 . The term “embed,” as used in the claim and in the corresponding portions of the specification, means “contact sufficiently to secure thereon and/or therein.” Accordingly, the support structure  17  shown in  FIG. 2A  is embedded by the elastomer  12  even though the elastomer  12  does not fully enclose the support structure  17 . Additionally, as shown in  FIG. 2B , the support structure  17  can be located at any level or height within the elastomer  12  without departing from the scope of the present invention. While the passageways  19  are shown as extending completely through the support structure  17 , the invention includes passageways  19  that extend partially through the support structure  17 .  
      Referring again to  FIG. 2A , in one embodiment, it is preferred that the support structure  17  be embedded on the elastomer  12 , with the elastomer penetrating the support structure  17 . The support structure  17  being generally along a major material surface  38  (i.e., the support structure  17  is generally along the top of the material).  
      The fibers  14  are preferably, but not necessarily, formed of aramid fibers. Referring to  FIG. 4 , the fibers  14  can be woven to form a cloth  16  that is disposed on and/or within the elastomer  12 . The cloth layer  16  can be formed of woven aramid fibers or other types of fiber. The aramid fibers  14  block and redirect vibrational energy that passes through the elastomer  12  to facilitate the dissipation of vibrations. The aramid fibers  18  redirect vibrational energy along the length of the fibers  18 . Thus, when the plurality of aramid fibers  18  are woven to form the cloth  16 , vibrational energy emanating from the implement  20  that is not absorbed or dissipated by the elastomer layer  12  is redistributed evenly along the material  10  by the cloth  16  and preferably also further dissipated by the cloth  16 .  
      It is preferable that the aramid fibers  18  are formed of a suitable polyamide fiber of high tensile strength with a high resistance to elongation. However, those of ordinary skill in the art will appreciate from this disclosure that any aramid fiber suitable to channel vibration can be used to form the support structure  17  without departing from scope of the present invention. Additionally, those of ordinary skill in the art will appreciate from this disclosure that loose aramid fibers or chopped aramid fibers can be used to form the support structure  17  without departing from the scope of the present invention. The aramid fibers may also be formed of fiberglass or the like.  
      When the aramid fibers  18  are woven to form the cloth  16 , it is preferable that the cloth  16  include at least some floating aramid fibers  18 . That is, it is preferable that at least some of the plurality of aramid fibers  18  are able to move relative to the remaining aramid fibers  18  of the cloth  16 . This movement of some of the aramid fibers  18  relative to the remaining fibers of the cloth converts vibrational energy to heat energy.  
      The material  10  may be configured and adapted to form an insert for shoe. When the material  10  is configured to form a shoe insert, the material  10  is preferably adapted to extend along an inner surface of the shoe from a location proximate to a heel of the shoe to the toe of the shoe. In addition to forming a shoe insert, the material  10  can be located along the sides of the shoe to protect the wearer&#39;s foot from lateral impact.  
      The material  10  may be configured and adapted to form a grip  22  for an implement such as a bat, having a handle  24  and a proximal end  26  (i.e., the end near to where the bat is normally gripped). The material  10  is preferably adapted to enclose a portion of the handle  24  and to enclose the proximal end  26  of the bat or implement  20 . As best shown in  FIGS. 7 and 8 , it is preferable that the grip  22  be formed as a single body that completely encloses the proximal end of the implement  20 . The material  10  may be also be configured and adapted to form a grip  22  for a tennis racket or similar implement  20  having a handle  24  and a proximal end  26 .  
      While the grip  22  will be described below in connection with a baseball or softball bat, those of ordinary skill in the art will appreciate that the grip  22  can be used with any of the equipment, tools, or devices mentioned above without departing from the scope of the present invention.  
      When the grip  22  is used with a baseball or softball bat, the grip  22  preferably covers approximately seventeen (17) inches of the handle of the bat as well as covers the knob (i.e., the proximal end  26  of the implement  20 ) of the bat. The configuration of the grip  22  to extend over a significant portion of the bat length contributes to increased vibrational damping. It is preferred, but not necessary, that the grip  22  be formed as a single, contiguous, one-piece member.  
      Referring to  FIG. 1 , the baseball bat (or implement  20 ) has a handle  24  including a handle body  28  having a longitudinal portion  30  and a proximal end  26 . The material  10  preferably encases at least some of the longitudinal portion  30  and the proximal end  26  of the handle  24 . The grip material  10  can incorporate any of the above-described support structures  17 . The aramid fiber layer  14  is preferably formed of woven aramid fibers  18 .  
      As best shown in  FIGS. 7 and 8 , the preferred grip  22  is adapted for use with an implement  20  having a handle and a proximal handle end. The grip  22  includes a tubular shell  32  having a distal open end  34  adapted to surround a portion of the handle and a closed proximal end  36  adapted to enclose the proximal end of the handle. It is preferable not necessary, that the material completely enclose the proximal end  26  of the handle. The tubular shell  32  is preferably formed of the material  10  which dissipates vibration.  
      Multiple methods can be used to produce the composite or multi-layer material  10  of the present invention. Briefly speaking, one method is to extrude the material  10  by pulling a support structure  17  from a supply roll while placing the elastomer layer on both sides of the support structure  17 . A second method of producing the material  10  of the present invention is to weave a fiber onto the implement  20  and then to mold the elastomer  12  thereover. Alternatively, a support structure can be pressure fit to an elastomer to form the material  10 . Those of ordinary skill in the art will appreciate from this disclosure that any other known manufacturing methods can be used to form the material  10  without departing from the scope of the present invention. Any of the below described methods can be used to form a material  10  or grip  22  having any of the above specified Shore A Durometers and incorporating any of the above-described support structures  17 .  
      More specifically, one preferred method of making the material  10  includes:  
      providing an uncured elastomer  12 . A cloth layer is positioned on and/or within the uncured elastomer  12 . The cloth layer is formed by a plurality of woven aramid fibers  14 . The uncured elastomer  12  penetrates the cloth layer  16  to embed to the cloth  16 . The uncured elastomer  12  is at least partially cured to form the material  10 . The cloth layer  16  supports the cured elastomer  12  and facilitates the distribution and dissipation of vibration by the material  10 .  
      It is preferable that the elastomer  12  is cured so that some of the plurality of aramid fibers in the cloth layer  16  are able to move relative to the remaining plurality of aramid fibers  18 . It is also preferable that the material  10  be configured to form a grip for a bat and/or racquet having a handle  24  and the proximal end  26 . The grip  22  preferably encloses at least a portion of the handle  24  and the proximal end  26 .  
      Another aspect of the present invention is directed to a method of making a grip  22  for an implement  20  having a handle  24  and a proximal end  26 . The grip  22  is formed by a single layer material  10  adapted to regulate vibration. The method includes providing an uncured elastomer. A plurality of fibers  14  are positioned on and/or within the uncured elastomer  12 . The uncured elastomer  12  is at least partially cured to form the single layer material embedding the plurality of fibers. The single layer material  10  has first and second major material surfaces. The single layer material  10  is positioned over at least a portion of the handle  24  and over the proximal end  26  of the handle  24 . The first major material surface contacts the implement  20  and second major material surface of the single layer material  10  forms a surface for a user to grasp. This method can be used to form a grip  22  having any of the Shore A Durometers described above and can use any of the support structure  17  also described above.  
      In another aspect, the present invention is directed to a method of making a material  10  adapted to regulate vibration. The method includes providing a cloth  16  formed by a plurality of woven aramid fibers  14 . The cloth has first and second major surfaces. A first elastomer layer  12 A is placed on the first major surface of the cloth. A second elastomer layer  12 B is placed on the second major surface  25  of the cloth  16 . The first and second elastomer layers  12 A,  12 B penetrate the cloth  16  to form a single layer elastomer  12  having an embedded cloth  16  for support thereof.  
      In another aspect, the present invention is directed to a method of forming a material  10  including providing a cloth layer  16 . Positioning an elastomer  12  substantially over the cloth layer  16 . Applying pressure to the cloth layer  16  and the elastomer  12  to embed the cloth layer  16  on and/or in the elastomer  12  to form the material  10 . When using this sort of pressure fit technique, those ordinary skill in the art will appreciate from this disclosure that the cloth layer  16  and the elastomer  12  can be placed in a mold prior to applying pressure without departing from the scope of the present invention.  
      The covering of the proximal end of an implement  20  by the grip  22  results  
      in reduced vibration transmission and in improved counter balancing of the distal end of the implement  20  by moving the center of mass of the implement  20  closer to the hand of a user (i.e., closer to the proximal end  26 ). This facilitates the swinging of the implement  20  and can improve sports performance while reducing the fatigue associated with repetitive motion.  
       FIGS. 9-10  illustrate another embodiment of the present invention. As shown therein a cover in the form of a sleeve  210  is mounted on the handle or lower portion  218  of a baseball bat  210 . Sleeve  210  is premolded so that it can be fit onto the handle portion of the bat  212  in a quick and convenient manner. This can be accomplished by having the sleeve  210  made of a stretchable or resilient material so that its upper end  214  would be pulled open and could be stretched to fit over the knob  217  of the bat  212 . Alternatively, or in addition, sleeve  210  may be provided with a longitudinal slit  16  to permit the sleeve to be pulled at least partially open and thereby facilitate snapping the sleeve  210  over the handle  218  of the bat  212 . The sleeve would remain mounted in place due to the tacky nature of the sleeve material and/or by the application of a suitable adhesive on the inner surface of the sleeve and/or on the outer surface of handle  218 .  
      A characterizing feature of sleeve  210 , as illustrated in  FIGS. 9-10 , is that the lower end of the sleeve includes an outwardly extending peripheral knob  2220 . Knob  220  could be a separate cap snapped onto or secured in any other manner to the main portion of sleeve  210 . Alternatively, knob  220  could be integral with and molded as part of the sleeve  210 .  
      In a broad practice of this invention, sleeve  210  can be a single layer. The material would have the appropriate hardness and vibration dampening characteristics. The outer surface of the material would be tacky having high friction characteristics.  
      Alternatively, the sleeve  210  could be formed from a two layer laminate where the vibration absorbing material forms the inner layer disposed against the handle, with a separate tacky outer layer made from any suitable high friction material such as a thermoplastic material with polyurethane being one example. Thus, the two layer laminate would have an inner elastomer layer which is characterized by its vibration dampening ability, while the main characteristic of the outer elastomer layer is its tackiness to provide a suitable gripping surface that would resist the tendency for the user&#39;s hand to slide off the handle. The provision of the knob  220  also functions both as a stop member to minimize the tendency for the handle to slip from the user&#39;s hand and to cooperate in the vibration dampening affect.  
       FIG. 10  illustrates the preferred form of multilayer laminate which includes the inner vibration absorbing layer  222  and the outer tacky gripping layer  224  with an intermediate layer  226  made of a stiffening material which dissipates force. If desired layer  226  could be innermost and layer  224  could be the intermediate layer. A preferred stiffening material would be aramid fibers which could be incorporated in the material in any suitable manner as later described with respect to  FIGS. 19-22 . However, fiberglass or any high tensile strength fibrous material can be used as the stiffening material forming the layer. Additionally, in one embodiment, the stiffening layer is substantially embedded in or held in place by the elastomer layer(s).  
       FIG. 11  schematically shows what is believed to be the affect of the shock forces from vibration when the implement makes contact such as from the bat  212  striking a ball.  FIG. 11  shows the force vectors in accordance with a three layer laminate, such as illustrated in  FIG. 10 , wherein elastomeric layers  222 , 224  are made of a silicone material. The intermediate layer  226  is an aramid layer made of aramid fibers. The initial shock or vibration is shown by the lateral or transverse arrows  228  on each side of the sleeve laminate  210 . This causes the elastomeric layers  222 , 224  to be compressed along the arc  230 . The inclusion of the intermediate layer  226  made from a force dissipating material spreads the vibration longitudinally as shown by the arrows  232 . The linear spread of the vibration causes a rebound effect which totally dampens the vibration.  
      Laboratory tests were carried out at a prominent university to evaluate various grips mounted on baseball bats. In the testing, baseball bats with various grips were suspended from the ceiling by a thin thread; this achieves almost a free boundary condition that is needed to determine the true characteristics of the bats. Two standard industrial accelerometers were mounted on a specially fabricated sleeve roughly in positions where the left hand and the right hand would grip the bat. A known force was delivered to the bat with a standard calibrated impact hammer at three positions, one corresponding to the sweet spot, the other two simulating “miss hits” located on the mid-point and shaft of the bat. The time history of the force as well as the accelerations were routed through a signal conditioning device and were connected to a data acquisition device. This was connected to a computer which was used to log the data.  
      Two series of tests were conducted. In the first test, a control bat (with a standard rubber grip, WORTH Bat—model #C405) was compared to identical bats with several “Sting-Free” grips representing practices of the invention. These “Sting-Free” grips were comprised of two layers of pure silicone with various types of high tensile fibrous material inserted between the two layers of silicone. The types of KEVLAR, a type of aramid fiber that has high tensile strength, used in this test were referenced as follows: “005”, “645”, “120”, “909”. Also, a bat with just a thick layer of silicone but no KEVLAR was tested. With the exception of the thick silicone (which was deemed impractical because of the excessive thickness), the “645” bat showed the best reduction in vibration magnitudes.  
      The second series of tests were conducted using EASTON Bats (model #BK8) with the “645” KEVLAR in different combinations with silicone layers: The first bat tested was comprised of one bottom layer of silicone with a middle layer of the “645” KEVLAR and one top layer of silicone referred to as “111”. The second bat test was comprised of two bottom layers of silicone with a middle layer of KEVLAR and one top layer of silicone referred to as “211”. The third bat tested was comprised of one bottom layer of silicone with a middle layer of KEVLAR and two top layers of silicone referred to as “112”. The “645” bat with the “111” configuration showed the best reduction in vibration magnitudes.  
      In order to quantify the effect of this vibration reduction, two criteria were defined: (I) the time it takes for the vibration to dissipate to an imperceptible value; and, (2) the magnitude of vibration in the range of frequencies at which the human hand is most sensitive.  
      The sting-free grips reduced the vibration in the baseball bats by both quantitative measures. In particular, the “645” KEVLAR in a “111” configuration was the best in vibration reduction. In the case of a baseball bat, the “645” reduced the bat&#39;s vibration in about ⅕ the time it took the control rubber grip to do so. The reduction in peak magnitude of vibration ranged from 60% to 80%, depending on the impact location and magnitude.  
      It was concluded that the “645” KEVLAR grip in a “111” combination reduces the magnitude of sensible vibration by 80% that is induced in a baseball bat when a player hits a ball with it. This was found to be true for a variety of impacts at different locations along the length of the bat. Hence, a person using the “Sting-Free” grips of the invention would clearly experience a considerable reduction in the sting effect (pain) when using the “Sting-free” grip than one would with a standard grip.  
      In view of the above tests a particularly preferred practice of the invention involves a multilayer laminate having an aramid such as KEVLAR, sandwiched between layers of pure silicone. The above indicated tests show dramatic results with this embodiment of the invention. As also indicated above, however, the laminate could comprise other combinations of layers such as a plurality of bottom layers of silicone or a plurality of top layers of silicone. other variations include a repetitive laminate assembly wherein a vibration dampening layer is innermost with a force dissipating layer against the lower vibration dampening layer and then with a second vibration dampening layer over the force dissipating layer followed by a second force dissipating layer, etc. with the final laminate layer being a gripping layer which could also be made of vibration dampening material. Among the considerations in determining which laminate should be used would be the thickness limitations and the desired vibration dampening properties.  
      The various layers could have different relative thicknesses. Preferably, the vibration dampening layer, such as layer  222 , would be the thickest of the layers. The outermost gripping layer, however, could be of the same thickness as the vibration dampening layer, such as layer  224  shown in  FIG. 10  or could be a thinner layer since the main function of the outer layer is to provide sufficient friction to assure a firm gripping action. A particularly advantageous feature of the invention where a force dissipating stiffening layer is used is that the force dissipating layer could be very thin and still achieve its intended results. Thus, the force dissipating layer would preferably be the thinnest of the layers, although it might be of generally the same thickness as the outer gripping layer. If desired the laminate could also include a plurality of vibration dampening layers (such as thin layers of gel material) and/or a plurality of stiffening force dissipating layers. Where such plural layers are used, the various layers could differ in the thickness from each other.  
       FIGS. 9-10  show the use of the invention where the sleeve  210  is mounted over a baseball bat  212  having a knob  217 . The same general type structure could also be used where the implement does not have a knob similar to a baseball bat knob.  FIG. 12 , for example, illustrates a variation of the invention wherein the sleeve  210 A would be mounted on the handle  218 A of an implement that does not terminate in any knob. Such implement could be various types of athletic equipment, tools, etc. The sleeve  210 A, however, would still have a knob  2220 A which would include an outer gripping layer  224 A, an intermediate force dissipating layer  226 A and an inner vibration dampening layer  222 A. In the embodiment shown in  FIG. 12 , the handle  218 A extends into the knob  220 A. Thus, the inner layer  222 A would have an accommodating recess  34  for receiving the handle  218 A. The inner layer  222 A would also be of greater thickness in the knob area as illustrated.  
       FIG. 13  shows a variation where the sleeve  210 B fits over handle  218 B without the handle  218 B penetrating the knob  220 B. As illustrated, the outer gripping layer  224 B would be of uniform thickness both in the gripping area and in the knob. Similarly, the intermediate force dissipating layer  226 B would also be of uniform thickness. The inner shock absorbing layer  222 B, however, would completely occupy the portion of the knob inwardly of the force dissipating layer  226 B since the handle  218 B terminates short of the knob  2220 B.  
       FIG. 14  shows a variation of the invention where the gripping cover  236  does not include a knob. As shown therein, the gripping cover would be mounted over the gripping area of a handle  238  in any suitable manner and would be held in place either by a previously applied adhesive or due to the tacky nature of the innermost vibration dampening layer  240  or due to resilient characteristics of the cover  236 . Additionally, the cover might be formed directly on the handle  238 .  FIG. 16 , for example, shows a cover  236 B which is applied in the form of tape.  
      As shown in  FIG. 14  the cover  236  includes one of the laminate variations where a force dissipating layer  242  is provided over the inner vibration dampening layer  240  with a second vibration dampening layer  244  applied over force dissipating layer  242  and with a final thin gripping layer  246  as the outermost layer. As illustrated, the two vibration dampening layers  240  and  244  are the thickest layers and may be of the same or differing thickness from each other. The force dissipating layer  242  and outer gripping layer  244  are significantly thinner.  
       FIG. 15  shows a cover  236 A mounted over a hollow handle  238 A which is of non-circular cross-section. Handle  238 A may, for example, have the octagonal shape of a tennis racquet.  
       FIG. 16  shows a further cover  236 B mounted over the handle portion of tool such as hammer  248 . As illustrated, the cover  236 B is applied in tape form and would conform to the shape of the handle portion of hammer  248 . Other forms of covers could also be applied rather than using a tape. Similarly, the tape could be used as a means for applying a cover to other types of implements.  
       FIG. 17  illustrates a cover  236 C mounted over the end of a handlebar, such as the handlebar of various types of cycles or any other device having a handlebar including steering wheels for vehicles and the like.  FIG. 17  also illustrates a variation where the cover  236 C has an outer contour with finger receiving recesses  252 . Such recesses could also be utilized for covers of other types of implements.  
       FIG. 18  illustrates a variation of the invention where the cover  236 D is mounted to the handle portion of an implement  254  with the extreme end  256  of the implement being bare. This illustration is to show that the invention is intended to provide a vibration dampening gripping cover for the handle of an implement and that the cover need not extend beyond the gripping area. Thus, there could be portions of the implement on both ends of the handle without having the cover applied to those portions.  
      In a preferred practice of the invention, as previously discussed, a force dissipating stiffening layer is provided as an intermediate layer of a multilayer laminate where there is at least one inner layer of vibration dampening material and an outer layer of gripping material with the possibility of additional layers of vibration dampening material and force dissipating layers of various thickness. As noted the force dissipating layer could be innermost. The invention may also be practiced where the laminate includes one or more layers in addition to the gripping layer and the stiffening layer and the vibration dampening layer. Such additional layer(s) could be incorporated at any location in the laminate, depending on its intended function (e.g., an adhesive layer, a cushioning layer, etc.).  
      The force dissipating layer could be incorporated in the laminate in various manners.  FIG. 19 , for example, illustrates a force dissipating stiffening layer  258  in the form of a generally imperforate sheet.  FIG. 20  illustrates a force dissipating layer  260  in the form of an open mesh sheet. This is a particularly advantageous manner of forming the force dissipating layer where it is made of KEVLAR fibers.  FIG. 21  illustrates a variation where the force dissipating layer  262  is formed from a plurality of individual strips of material  264  which are parallel to each other and generally identical to each other in length and thickness as well as spacing.  FIG. 22  shows a variation where the force dissipating layer  266  is made of individual strips  268  of different sizes and which could be disposed in a more random fashion regarding their orientation. Although all of the strips  268  are illustrated in  FIG. 22  as being parallel, non-parallel arrangements could also be used.  
      The vibration dampening grip cover of this invention could be used for a wide number of implements. Examples of such implements include athletic equipment, hand tools and handlebars. For example, such athletic equipment includes bats, racquets, sticks, javelins, etc. Examples of tools include hammers, screwdrivers, shovels, rakes, brooms, wrenches, pliers, knives, handguns, air hammers, etc. Examples of handlebars include motorcycles, bicycles and various types of steering wheels.  
      A preferred practice of this invention is to incorporate a force dissipating layer, particularly an aramid, such as KEVLAR fiber, into a composite with at least two elastomers. One elastomer layer would function as a vibration dampening material and the other outer elastomer layer which would function as a gripping layer. The outer elastomer layer could also be a vibration dampening material. Preferably, the outer layer completely covers the composite.  
      There are an almost infinite number of possible uses for the composite of laminate of this invention. In accordance with the various uses the elastomer layers may have different degrees of hardness, coefficient of friction and dampening of vibration. Similarly, the thicknesses of the various layers could also vary in accordance with the intended use. Examples of ranges of hardness for the inner vibration dampening layer and the outer gripping layer (which may also be a vibration absorbing layer) are 5-70 Durometer Shore A. One of the layers may have a range of 5-20 Durometer Shore A and the other a range of 30-70 Durometer Shore A for either of these layers. The vibration dampening layer could have a hardness of less than 5, and could even be a 000 Durometer reading. The vibration dampening material could be a gel, such as a silicone gel or a gel of any other suitable material. The coefficient of friction as determined by conventional measuring techniques for the tacky and non-porous gripping layer is preferably at least 0.5 and may be in the range of 0.6-1.5. A more preferred range is 0.7-1.2 with a still more preferred range being about 0.8-1. The outer gripping layer, when also used as a vibration dampening layer, could have the same thickness as the inner layer. When used solely as a gripping layer the thickness could be generally the same as the intermediate layer, which might be about {fraction (1/20)} to ¼ of the thickness of the vibration dampening layer.  
      The grip cover of this invention could be used with various implements as discussed above. Thus, the handle portion of the implement could be of cylindrical shape with a uniform diameter and smooth outer surface such as the golf club handle  238  shown in  FIG. 12 . Alternatively, the handle could taper such as the bat handle shown in  FIGS. 9-10 . Other illustrated geometric shapes include the octagonal tennis racquet handle  238 A shown in  FIG. 15  or a generally oval type handle such as the hammer  248  shown in  FIG. 16 . The invention is not limited to any particular geometric shape. In addition, the implement could have an irregular shape such as a handle bar with finger receiving depressions as shown in  FIG. 17 . Where the outer surface of the implement handle is of non-smooth configuration the inner layer of the cover could press against and generally conform to the outer surface of the handle and the outermost gripping layer of the cover could include its own finger receiving depressions. Alternatively, the cover may be of uniform thickness of a shape conforming to the irregularities in the outer surface of the handle.  
      It is recognized by those skilled in the art, that changes may be made to the above-described embodiments of the invention without departing from the broad inventive concept thereof. For example, the material  10  may include additional layers (e.g., two or more additional layers) without departing from the scope of the present invention. It is understood, therefore, that this invention is not limited to the particular embodiments disclosed, but is intended to cover all modifications which are within the spirit and scope of the invention as defined by the appended claims and/or shown in the attached drawings.