Sandwich-structure flat actuator and application to structural torsion

A flat, sandwich-structure actuator having a length in a direction X, a width in a direction Y and a thickness in a direction Z, said actuator comprising:

• at least three flat layers superposed in a sandwich-structure symmetrical relative to the mid plane of the actuator promoting a flat shearing deformation of said sandwich-structure, comprising:
• at least one layer of a fabric whose warp and weft comprise rigid fibers respectively disposed parallel to said directions X and Y, forming a mesh of juxtaposed parallelograms, each layer of fabric having its warp and weft oriented in the same directions X, and Y, and
• at least one piezoelectric active flat layer capable of lengthening or retracting in an active direction, the active direction of each piezoelectric flat layer being oriented along one and the same diagonal of said parallelograms of said mesh,
• the faces of said piezoelectric active flat layer in contact with a layer of fabric being fixedly attached to said layer of fabric on whole the surface of said piezoelectric active flat layer, and
• first and second attachment zones designed for transmission of said flat shearing deformation of said sandwich-structure, said first and second attachment zones being of elongated shape and parallel to one of said directions X and Y and being respectively disposed on the opposite outer faces of said sandwich structure along opposite ends of this latter.