Deployable Membrane Structure

Abstract

A deployable structure ( 10 ) includes at least two membranes ( 20 ) arranged overlying each other and spaced apart from each other. A deployable perimeter truss structure ( 40 ) encircles the at least two membranes ( 20 ). A transition truss structure ( 80 ) connects the membranes ( 20 ) to the perimeter truss structure ( 40 ). The perimeter truss structure ( 40 ), transition truss structure ( 80 ), and membranes ( 20 ) form a pre-loaded truss structure in which the membranes comprise integral tension transmitting components of the tensioned truss structure.

1 . A deployable structure comprising:
 at least two membranes arranged overlying each other and spaced apart from each other;   a deployable perimeter truss structure encircling the at least two membranes; and   a transition truss structure connecting the membranes to the perimeter truss structure, wherein the perimeter truss structure, transition truss structure, and membranes form a pre-loaded truss structure in which the membranes comprise integral tension transmitting components of the pre-loaded truss structure.   
     
     
         2 . The deployable structure recited in  claim 1 , further comprising:
 a catenary associated with each of the at least two membranes, each catenary encircling its associated membrane and being connected to its associated membrane at interfaces spaced about a periphery of the associated membrane; and   tension springs interconnecting adjacent and overlying ones of the interfaces on the at least two membranes.   
     
     
         3 . The deployable structure recited in  claim 2 , wherein the transition truss structure is connected to the interfaces to thereby connect the membranes to the perimeter truss structure. 
     
     
         4 . The deployable structure recited in  claim 2 , wherein each catenary is connected to the interfaces so as to be slidable relative to the associated membrane. 
     
     
         5 . The deployable structure recited in  claim 2 , wherein each catenary is connected to the interfaces so as to be fixed relative to the associated membrane. 
     
     
         6 . The deployable structure recited in  claim 1 , wherein the perimeter truss structure comprises rigid truss members deployable to define a closed periphery centered on a central longitudinal axis of the deployable structure. 
     
     
         7 . The deployable structure recited in  claim 6 , wherein the rigid truss members comprise:
 longerons interconnected to form radially stiff first and second peripheral chords centered on the longitudinal axis and spaced apart along the longitudinal axis; and   axially stiff batens extending axially between and interconnecting the first and second peripheral chords.   
     
     
         8 . The deployable structure recited in  claim 6 , wherein the perimeter truss structure further comprises diagonals that interconnect the rigid truss members. 
     
     
         9 . The deployable structure recited in  claim 2 , wherein the transition truss structure comprises at least one cable interconnecting the interfaces on each membrane to the perimeter truss structure. 
     
     
         10 . The deployable structure recited in  claim 1 , wherein the at least two membranes comprise sunshields. 
     
     
         11 . The deployable structure recited in  claim 1 , wherein the at least two membranes comprise a film with an aluminized surface. 
     
     
         12 . The deployable structure recited in  claim 1 , wherein the at least two membranes comprise a polyimide film. 
     
     
         13 . The deployable structure recited in  claim 2 , wherein the springs exert a spring force that urges the interfaces toward each other and tensions the catenaries, which applies a tension across the membranes and through the transition truss to the perimeter truss. 
     
     
         14 . The deployable structure recited in  claim 2 , wherein the springs exerting a spring force that urges the interfaces toward each other places the perimeter truss in compression. 
     
     
         15 . The deployable structure recited in  claim 13 , wherein the catenaries help distribute the tension evenly across the membranes.