טכניון מכון טכנולוגי לישראל
הטכניון מכון טכנולוגי לישראל - בית הספר ללימודי מוסמכים  
M.Sc Thesis
M.Sc StudentGetz Roey
SubjectTunable Band-Gaps in Soft Electroactive Composites
DepartmentDepartment of Mechanical Engineering
Supervisor Assistant Professor Gal Shmuel
Full Thesis textFull thesis text - English Version


Abstract

Dielectric elastomers deform and stiffen when subjected to voltage. This work demonstrates how fiber composites made of incompressible dielectric elastomers exhibit complete band gaps - frequency ranges in which elastic wave propagation is prohibited, irrespective of its polarization and direction. Importantly, we demonstrate that these gaps are tunable by the voltage. Our idea is simple: as the electric field induces significant geometrical changes and modifies the constituent properties, the characteristics of the incremental motion and the resultant band gaps will change too.

To this end, we first analytically determine the quasi-static response of a wide class of composites to an electric field along the fibers. We then formulate and calculate incremental motions of general polarization propagating in the deformed composite, when modeled as a bulk, and when modeled as a plate of finite thickness. We solve the resultant equations numerically using an adaptation of the plane wave expansion method we developed, and evaluate the band structure of exemplary composites along with those made of commercially available materials. To arrive at the findings above, we apply the numerical schemes to a composite with circular fibers, and parametrically study the propagation dependency on the phase properties, volume fraction, film thickness, and most importantlythe applied electric voltage. Our results are another step towards the use of soft dielectric films as active wave manipulators.