|M.Sc Student||Ziser Yotam|
|Subject||Experimental Slowing of Flexural Waves in Dielectric|
Elastomer Films by Voltage
|Department||Department of Mechanical Engineering||Supervisor||Assistant Professor Gal Shmuel|
|Full Thesis text|
In the presence of electric fields, dielectric elastomers can experience large strains accompanied with a change in their physical properties. The standard actuation mechanism is established by coating the surfaces perpendicular to the thickness of an elastomeric film with deformable electrodes, and connecting them to a voltage source; ensuing Coulomb forces between accumulated charge cause deformation and change the electromechanical response. Various applications were realized based on this electrostatic actuation, such as tunable valves, noise filters, and soft robotics.
The potential of dielectric elastomers as tunable waveguides has been extensively explored using theory. Corresponding experimental work?the focus of this thesis?has yet to be realized. Specifically, recent theoretical works show that changes in the electromechanical response can be harnessed to tune the propagation of superposed elastic waves. We experimentally demonstrate this concept by manipulating plate or Lamb waves in a dielectric elastomer film, focusing on the flexural mode at low frequencies. To this end, we design an experimental apparatus to pre-stretch, actuate, excite waves at low frequencies in a VHB? 4910 film, and measure the velocity of the fundamental flexural mode. From experimental measurements, we have calculated the wave velocity when the film is clamped in its initial configuration and when pre-stretched, under different magnitudes of voltage. Measurements from films which were identically pre-stretched, while subjected to different magnitudes of voltages, show that at low frequencies the wave velocity is slowed down by voltage. Our results provide experimental proof of concept for the application of deformable dielectrics as tunable waveguides.