Ball bat with a strain energy optimized barrel

Abstract

A ball bat exhibits minimal strain energy losses associated with bat-ball collisions by employing one or more integral interface shear control zones (ISCZs) in the bat barrel, and/or by the selection and placement of specific composite materials with respect to the neutral axes in the barrel walls.

1 . A ball bat including a barrel, a handle, and a tapered section joining the barrel to the handle, with the barrel comprising: 
 a substantially cylindrical outer wall;    a substantially cylindrical inner wall located within the outer wall; and    an ISCZ comprising a flexible material, and separating the outer wall from the inner wall, wherein the outer wall and the inner wall blend together at at least one end of the barrel.    
     
     
         2 . The ball bat of  claim 1  wherein the flexible ISCZ material comprises a fluoropolymer.  
     
     
         3 . The ball bat of  claim 2  wherein the flexible ISCZ material comprises polytetraflouroethylene.  
     
     
         4 . The ball bat of  claim 1  wherein the flexible ISCZ material comprises polyamide.  
     
     
         5 . The ball bat of  claim 1  wherein the flexible ISCZ material comprises cellophane.  
     
     
         6 . The ball bat of  claim 1  wherein the ISCZ comprises a layer of a bond-inhibiting material.  
     
     
         7 . The ball bat of  claim 1  wherein the outer wall and the inner wall each comprise at least one fiber-reinforced resin composite material.  
     
     
         8 . The ball bat of  claim 7  wherein the composite material includes at least one material selected from the group consisting of glass, graphite, boron, carbon, aramid, and ceramic.  
     
     
         9 . The ball bat of  claim 1  wherein the outer wall is divided into a first outer section and a first inner section by a first neutral axis, and the inner wall is divided into a second outer section and a second inner section by a second neutral axis.  
     
     
         10 . The ball bat of  claim 9  wherein the first and second outer sections each comprise a structural glass-reinforced epoxy resin, and the first and second inner wall sections each comprise a graphite-reinforced epoxy resin.  
     
     
         11 . The ball bat of  claim 1  further comprising a substantially cylindrical additional wall located within the inner wall.  
     
     
         12 . The ball bat of  claim 11  wherein the additional wall is separated from the inner wall by an additional interface shear control zone.  
     
     
         13 . The ball bat of  claim 1  wherein the ISCZ is located approximately at the radial midpoint of the barrel, such that the outer wall and the inner wall have approximately the same radial thickness.  
     
     
         14 . The ball bat of  claim 1  wherein the outer wall and the inner wall blend together at both ends of the barrel.  
     
     
         15 . The ball bat of  claim 1  wherein the outer wall and the inner wall blend together at the tapered section of the ball bat.  
     
     
         16 . A ball bat including a barrel, a handle, and a tapered section joining the barrel to the handle, with the barrel comprising: 
 a substantially cylindrical outer wall;    a substantially cylindrical inner wall located within the outer wall; and    an ISCZ separating the outer wall from the inner wall, with the ISCZ comprising at least one material selected from the group consisting of fluorinated ethylene propylene, polyvinyl fluoride, ethylenetetrafluoroethylene, polychlorotrifluoroethylene, polytetraflouroethylene, polymethylpentene, polyamide, and cellophane.    
     
     
         17 . The ball bat of  claim 16  wherein the outer wall and the inner wall blend together at at least one end of the barrel.  
     
     
         18 . A ball bat including a barrel, a handle, and a tapered section joining the barrel to the handle, with the barrel comprising: 
 a substantially cylindrical outer wall;    a substantially cylindrical inner wall located within the outer wall; and    a flexible bond-inhibiting layer separating the outer wall from the inner wall.    
     
     
         19 . The ball bat of  claim 18  wherein the outer wall and the inner wall blend together at at least one end of the barrel.  
     
     
         20 . The ball bat of  claim 18  wherein the bond-inhibiting layer comprises at least one material selected from the group consisting of fluorinated ethylene propylene, polyvinyl fluoride, ethylenetetrafluoroethylene, polychlorotrifluoroethylene, polytetraflouroethylene, polymethylpentene, polyamide, and cellophane.