Fiber tensioning device and method of making prestressed structures

Abstract

A process for forming a prestressed structure that includes: winding a plurality of fibers around a structure in order to compressively prestress the structure; wherein the winding is achieved by a fiber tensioning device that includes: a plurality of axles rotatably supported by the frame, each axle having a drum that engages the plurality of aligned fibers, each axle also having a sprocket; a chain for coupling each of the sprockets; a brake connected to the chain which opposes the motion of the chain thus increasing the tension in the plurality of aligned fibers that are in contact with said drums; and whereby the aligned fibers are wound onto the structure under increased tension thus imparting compressive pressure between the aligned fibers on to the wound structure.

1 . A filament winding process for forming a prestressed winding of fibers on a structure, the process comprising:
 winding of a plurality of aligned fibers around a structure in order to compressively prestress said structure;   wherein said winding is achieved by a fiber tensioning device for winding a plurality of aligned fibers and increasing the tension in the aligned fibers during the winding process, the fiber tensioning device comprising:   a frame;   a plurality of axles rotatably supported by the frame, each axle having a drum that engages the plurality of aligned fibers, each axle also having a sprocket;   a chain for coupling each of the sprockets;   a brake connected to the chain which opposes the motion of the chain thus increasing the tension in the plurality of aligned fibers that are in contact with said drums; and   whereby the aligned fibers are wound onto the structure under increased tension thus imparting compressive pressure between the aligned fibers on to the wound structure.   
     
     
         2 . The process of  claim 1  further comprising passing the plurality of aligned fibers through a resin bath before winding of the plurality of aligned fibers around the structure. 
     
     
         3 . The process of  claim 1  further comprising contacting the plurality of aligned fibers with a resin before winding of the plurality of aligned fibers around the structure. 
     
     
         4 . The process of  claim 2  further comprising curing the resin on the fibers that were wound on the structure. 
     
     
         5 . The process of  claim 3  further comprising curing the resin on the fibers that were wound on the structure. 
     
     
         6 . The process of  claim 1  wherein said plurality of fibers is wound onto said structure in a pattern. 
     
     
         7 . The process of  claim 1  wherein said plurality of fibers is wound onto said structure in a predetermined pattern. 
     
     
         8 . The process of  claim 1  wherein said plurality of fibers is wound onto said structure in a helical pattern. 
     
     
         9 . The process of  claim 1  wherein said structure is a pressure vessel, a pipe, a rocket motor casing, a tank, or a gun barrel. 
     
     
         10 . The process of  claim 1  wherein said structure is a concrete structure. 
     
     
         11 . The process of  claim 1  wherein said structure is a concrete pipe, a concrete tank, a concrete piling or other solid or hollow concrete structure. 
     
     
         12 . The process of  claim 1  wherein said fiber tensioning device con prising at least four axles wherein each of the four axles is coupled to said chain and is controlled by said brake for increasing the tension in the plurality of aligned fibers that are in contact with said drums attached to said axles. 
     
     
         13 . The process of  claim 1  wherein said plurality of aligned fibers are selected from the group consisting of carbon fibers, graphite fibers, fiberglass fibers, nylon fibers, polyaramid fibers and combinations thereof. 
     
     
         14 . The process of  claim 2  wherein said resin is selected from the group consisting of polyesters, epoxy resins, vinyl ester resins and combinations thereof. 
     
     
         15 . The process of  claim 1  wherein the process is a wet winding process. 
     
     
         16 . The process of  claim 1  wherein said fiber tensioning device further comprises friction-enhancing bearings to increase the braking torque in the axles. 
     
     
         17 . The process of  claim 1  wherein the aligned fibers are wound on to the wound article under higher tension. 
     
     
         18 . The process of  claim 1  wherein the brake controls the chain so as to provide an appropriate level or torque to the wheels. 
     
     
         19 . The process of  claim 1  wherein the brake modulates the fiber tension. 
     
     
         20 . The process of  claim 1  wherein the brake modulates the drag torque.