Dielectric elastomer cylindrical actuators: Electromechanical modelling and experimental evaluation

This paper presents an experimentally validated electromechanical model of cylindrical actuators made of dielectric elastomers with compliant electrodes. Modelling was based on independent electrical and mechanical analyses of the specific configuration of the device. The expressions of the electrostatic pressures exerted by the electrodes in response to an applied voltage were formulated and inserted into the expressions of the actuator mechanical deformations, obtained by assuming linearly elastic stress-strain constitutive equations of the material for small strains. Values of axial strains expected from the model well fit those recorded from a realised actuator, electrically stimulated by step-wise high voltages. This actuator has carbon grease electrodes smeared on a cylinder-shaped silicone elastomer, showing a room-temperature relative dielectric constant of 3 within a wide frequency range (10-109 Hz). An axial strain of 4.5% due to a voltage per unit wall-thickness of 100 V/µm was measured at a 5% axial prestrain, around which the material held a Young’s modulus of 5 MPa.