A sandwich beam with electrostatically tunable bending stiffness

The tuning of the bending stiffness of structural elements is of interest for, among other things, the suppression of vibrations related to resonance phenomena. For a given cross-sectional area and geometry, the variation of the elastic properties of the material composing the structure provides a viable approach to this task. Only very limited options are available for such changes in material properties. The use of NiTi shape memory alloys has been proposed for this purpose. A new, energetically less expensive method for the modification of the bending stiffness of sandwich beams is presented. The proposed method makes use of electrostatic forces to modify the transfer of shear stresses at the interface between the faces and the core of the sandwich. Changes in bending stiffness of up to 18 times could be obtained for a prototype beam. A simple model for describing the behavior of the beam is presented.