Influence of the active-to-passive area ratio on the electrically induced strain of a fiber-reinforced dielectric elastomer actuator

Abstract

There is an increasing interest to use novel elastomers with inherent or modified advanced dielectric and mechanical properties, as components of dielectric elastomer actuators (DEA). This requires corresponding techniques to assess their electromechanical performance. One performance criterion is the electrically induced deformation of the active electrode area. In this work, a rectangular DEA is used to investigate the influence of the ratio between the active electrode and the passive area on the actuator deformation. For this purpose, a dielectric silicone film is bonded on one surface to a unidirectional carbon fiber fabric. Thereby, highly anisotropic mechanical properties are implemented. When strains are applied perpendicular to the fiber direction, the composite hardly contracts in the fiber direction due to the superior stiffness of the fibers. In addition, the conductive fiber structure also acts as a highly anisotropic compliant electrode. By application of a second paste-like electrode onto the silicone film a DEA is created that operates in a pure shear configuration. This assembly enables the modification of the active-to-passive area ratio and the investigation of its effect on the actuator deformation. Image-based measurements are used to determine the strain of the active electrode area. The experimental results are compared to a lumped-parameter model that considers the electromechanical properties of the fiber-reinforced DEA. In summary, the ratio of the active-to-passive area has a significant influence on the measured deformation. Especially for novel actuator materials that do not exhibit large strains, an active-to-passive ratio of 50 % proves to be particularly advantageous.

Understanding the Impact of Active-to-Passive Area Ratio on Deformation in One-Dimensional Dielectric Elastomer Actuators with Uniaxial Strain State

“…To manufacture these DEAs, CNT-based sheets [27] or carbon-fiber-based textiles [26,28] are functionalized as electrodes, allowing for the assembly of strip actuators [29,30]. To investigate the influence of the active-to-passive ratio in the one-dimensional case, in this work, fiber-reinforced strip actuators are used.…”

Influence of Active-to-Passive Ratio on the Deformation in Circular Dielectric Elastomer Actuators

“…The lumped parameter model is derived by modeling a slice of the circular actuator with a network based on a mechanical structure for one-dimensional DEAs with a uniaxial strain state [ 21 , 22 ]. As shown in Figure 5 , the active and the passive areas are described by their respective spring compliances and with velocity v and radial displacement .…”

Highly anisotropic carbon fiber electrodes for DEAs and their dynamic non-monotonic conductive properties

“…Various options exist for anisotropic reinforcement fibers, including polyamide, polyethylene, glass, or carbon fibers. [10][11][12][13] Carbon fibers are especially advantageous due to their high stiffness, extreme anisotropy, and electrical conductivity, therefore, making them suitable for the use as an electrode material as well. 11,14 While carbon fibers posses superb mechanical stiffness under tension, their stiffness in compressive loading scenarios is limited due to buckling of the slender fibers.…”