Dual-bias airbeam

Abstract

An airbeam, inflated to create a structural member, has three functional layers in its wall: a flexible gas barrier and a braided reinforcing layer plus the novelty of an additional braided layer. Key design factors are the bias angles of the braids in the two braided layers: that of the inner one greater than 54.7 degrees bias angle and of the outer one less than 54.7 degrees bias angle. The two layers of braid being slipped over another allows the airbeam to be formed with bends for a wide variety of shapes.

1 . An inflatable structure having tubular form, comprising: 
 a gas barrier layer, an inner fiber layer and an outer fiber layer, said gas barrier layer being a closed, gas-tight envelope constructed using flexible material and including valve means for introducing and removing inflation gas; said inner fiber layer having a tubular braided form with a bias angle measured from a reference line lying parallel to the centerline of the tubular form of greater than 54.7 degrees; said outer fiber layer having a tubular form with a braided bias angle measured from a reference line lying parallel to the centerline of the tubular form of less than 54.7 degrees, said inner fiber layer and said outer fiber layer being adhesively bonded together.    
   
   
       2 . The inflatable structure of  claim 1  in which said inner fiber layer has a bias angle of less than 54.7 degrees and said outer fiber layer has a bias angle greater than 54.7 degrees.  
   
   
       3 . The inflatable structure of  claim 1  with a curved shape.  
   
   
       4 . The inflatable structure of  claim 1  with a tapered shape.