Air Force

Flexural hinge

Excellent for use in deploying membrane-like structures


Scientists at the Air Force Research Laboratory have invented novel components for membrane-like tensioned precision structures for use by space vehicles and satellites. The patented device described here is available for license to companies that would make, sell, or use it commercially.

A solar sail is the type of membrane-like deployed structure which could benefit from a flexural hinge.

Deployable structures are used when there are significant space restraints on cargo and the deployed structure is not needed until it arrives at its destination. Ideal examples include antennas that are deployed once a device reaches a transmit or receive location and solar panels that are folded like origami during space vehicle launch and subsequently unfolded upon attainment of orbit. Weight and compactness are common characteristics.

Signifigant effort has gone into the development of material for new deployable structures but what may receive less attention are the hinges that these structures rely on for deployment. Air Force researchers have not missed this issue and have developed a compliant hinge that is elastically flexible in order to provide relative rotation between the more rigid structures.

The compliant hinge is illustrated as coupled between rigid panels 40, which collectively define a tensioned precision structure 42. The structure also includes fasteners 44, clamping blocks 46, and positioning pins 48. The flexible intermediate portion allows for rotation, bending, and extension, and can interconnect rigid panels in tensioned precision structures and other applications.

The compliant hinges offer increased potential for customization regarding the location, size, stiffness, and materials as required by specific membrane-like deployable structures. In addition, the hinges can be engineered with known locations and stiffness properties. The shape determinacy of the tensioned structure using them can be significantly greater than a traditional membrane. The structural benefit provided by the relatively low in-plane shear compliance is the structure’s resistance to wrinkling, where wrinkling includes the out-of-plane deflection of an otherwise two -dimensional structure, for example, a membrane-like deployable structure. If a structural error is introduced, such as from fabrication, or thermal warping, the compliant hinges, as the only source of significant compliance in the structure, can adjust and deform to a new minimum strain energy stated without significant out of plane stresses.

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