Vibration and Aerodynamic Characteristics of Dielectric Elastomer Membranes of Various Shapes

The dielectric elastomer is a category of electroactive polymer capable of having large deformation under electric excitation and vice versa. They show great potential for proper maneuvering of small-scale aerial vehicles due to low density and fast actuation, and the successful design demands proper prediction of their overall dynamic characteristics. However, these characteristics cannot be accurately predicted from lower-order material approximation and/or one specific elastomer shape under a specific flow velocity, pretension, and relaxation. In this research, a comprehensive modal and aerodynamic analysis for VHB 4910 dielectric elastomer membrane of three different shapes are computationally investigated under different electric excitations, pretensions, and flow velocities using higher-order Ogden model. A finite element model and a two-way, fully coupled, fluid-structure interaction model are developed to obtain vibration and aerodynamic characteristics, respectively, for different membrane shapes. It is found that the variation of electric excitation, pretension, and air velocity is influential to alter the overall dynamics of the membrane and is unique to specific shapes. The rectangular membrane shows higher vibration frequency for the fundamental mode whereas the circular membrane provides higher frequencies in higher modes. Increased relaxation for a membrane prestretch higher than the moderate range of stretch ratio (λ= 3) demonstrates slight increase in lift coefficient within a small range of angle of attack followed by a decrease after exceeding that range. Both the rectangular and elliptical membranes show more flexibility to delay the stall compared to the circular membrane. The circular membrane is observed to have more potential for enhancing the aerodynamic performance and altering the flow field within a certain range of electric excitation and pretension. Computational results are compared with published experimental results to validate the corresponding models.