Session: 04-08-01: Dynamics and Control of Aerospace Structures

Paper Number: 70077

Start Time: Monday, 05:30 PM

70077 - On the Dynamic Response of a Dielectric Elastomer Membrane 

The dielectric elastomer (DE) material is a category of the electroactive polymers which produces large deformation under applied voltage. This property made the DE materials much promising as smart materials that can rapidly adapt to changes in environmental conditions due to their mechanical response to an electrical input. An electrostatic pressure is created when the DE material is subjected to an externally applied voltage which creates compression in the thickness direction and extension in the in-plane direction of the DE material. These deformation characteristics of the DE membrane under electric excitation over a wide range of frequencies offer significant advantages for various applications including electromechanical transducers, actuators, loudspeakers, programmable haptic surfaces, energy harvesting, and micro-air vehicles where large structural deformation and sensitivity of the applied voltage are beneficial. Therefore, in this study, a specimen of a hyperplastic elliptic DE membrane, VHB 4910 is considered to observe the structural dynamics and aerodynamic characteristics under external flow of air subjected to electric excitation. The hyperelastic coefficients to define the membrane model are based on the neo-Hooke theory. For the structural dynamic characteristics, a finite element model of the VHB 4910 model subjected to three different electric voltages is created to estimate the vibration frequency for the first four modes and determine the corresponding mode shapes. The frequencies obtained from the finite element model are compared to that of the analytical method by solving the Mathieu function. For the aerodynamic response, a fluid-structure interaction model is created under steady airflow by coupling the finite element model of the DE membrane with the computational fluid dynamics model of the surrounding air with low Reynolds number characteristics. The variations of the aerodynamic lift and drag coefficients and the aerodynamic efficiency are studied for a particular fluid velocity. In addition, the out-of-plane deformation of the membrane with different angles of attack subjected to different voltages are also investigated. It is found that the vibration frequency decreases as the voltage increases due to the softening effect of the voltage on the membrane creating the compressive stress along the thickness direction of the membrane. Also, the increase of the voltage results in the increase of the out-of-plane deformations of the membrane due to reduction of the pretension in the membrane resulting in lower stiffnesses. The chordwise deformation profiles of the elliptic membrane for different applied voltages are found to be parabolic in nature. At the same time, the out-of-plane deformation of the membrane is found maximum at the center of the membrane which increases with the increase of the voltage and the angle of attack. The reduction of the vibration frequency with the applied voltage indicates that the dynamic response of the membrane can be controlled by the application of an electric field. The aerodynamic lift coefficient is observed to increase with the angle of attack up to the critical value which is a trend similarly followed by the aerodynamic efficiency.

Presenting Author: Pratik Sarker Detroit Engineered Products

Authors:

Pratik Sarker Detroit Engineered Products
Uttam K. Chakravarty University of New Orleans