Electroactive Polymer Actuators in Dynamic Applications

Electroactive polymers (EAPs) have been widely employed as smart material for actuators in recent years. Numerous investigations have focused on static or quasi-static applications. For the use as actuators in the field of active vibration control (AVC); however, the dynamic behavior needs to be studied in detail and the inherent nonlinear effects demand new control concepts. Since AVC applications have only recently been considered for EAP actuators, only a few studies have been published in this area so far . In this paper, the nonlinearities in a dielectric elastomer (DE) actuator and their consequences for dynamic applications are analyzed on a theoretical level first and then shown to be practically relevant in an experimental setup. Afterward, two compensation methods are presented and their improving influence on the dynamic behavior proven. Finally, the DE actuator is included in an active closed-loop control system and its potential for AVC demonstrated. Furthermore, a MATLAB/SIMULINK model of the whole system is presented, its general validity shown, and its potential for future system development processes highlighted.

0 Nomenclature

Y

Young's modulus, .

E

Electrical field, V/m.

Nominal film thickness, m.

Active electrical width of DE film, m.

Equivalent mechanical width of DE film, m.

Nominal length of DE film, m.

V

Volume of DE film, .

c

Mechanical stiffness, N/m.

Lehr's damping ratio, 1.

x

Displacement, m.

Velocity, m/s.

Acceleration, .

Internal actuator force, N.

External actuator force, N.

Offset/amplitude-voltage, V.

i

Electrical current, A.

g

Gain factor of amplifier, 1.

Nominal capacity of the actuator, F.

Thickness strain, 1.

Longitudinal strain, 1.

Maxwell stress, .

Relative permittivity, 1.

Vacuum permittivity, F/m.

Angular frequency, 1/s.

f

Frequency, Hz.

Distortion factor, 1.

Actuator constant, .

Gain factor for voltage signal, 1.

Sensitivity of compensation, 1.