Effects of Thinner Compliant Electrodes on Self-Clearability of Dielectric Elastomer Actuators

A metalized plastic capacitor stands a higher chance to clear faults when embodied with thinner electrodes. However, it is not clear whether the same thickness effect applies to carbon-based compliant electrodes in clearing the defects in dielectric elastomer actuators (DEA). This experimental study showed that charcoal-powder compliant electrodes act like fuses and current limiters to successfully clear the defects of an acrylic dielectric elastomer actuator, provided a very thin electrode coating. For example, DEAs with 3 μm thick (average) charcoal-powder electrodes fast cleared faults and sustained high breakdown strength (300 to 400 MV/m), but the ones with thicker charcoal-powder electrodes (30 μm thick on average) succumbed to persisting breakdowns in a weaker electric field (200 to 300 MV/m). Thermo-gravitational analysis and differential scanning calorimetry showed that dielectric elastomer (3M VHB F9473PC) started to ignite at 350 ∘C, and charcoal powders (Mungyo charcoal pastel MP-12CP) started burning above 450 ∘C. This confirmed that flash ignition and its damping of charcoal powder is possible only with a very thin electrode coating relative to acrylic elastomer substrate thickness. Too thick of a charcoal-powder coating could lead to the spread of burning beyond the initial flash point, and incomplete burning that punctures the dielectric layer but shorts across opposite electrodes. With this insight, one can design self-clearable electrodes to improve the dielectric strength of dielectric elastomer actuators.

Vibrations of a cylindrical piezoshell filled with a fluid

Stationary oscillations of a piezoceramic cylindrical shell with thickness polarization under the action of a time-harmonic mechanical load in the form of an external pressure are considered. The shell has a finite length and is closed at the ends with rigid plates. The inner volume of the shell is filled with a non-viscous compressible liquid. A continuous thin electrode coating is applied to the cylindrical surfaces of the shell. Surface electrodes are considered open. The equations of axisymmetric oscillations and the corresponding boundary conditions at the ends are written in the problem statement for the shell. A problem is formulated also for determining the motion in the form of small oscillations of a liquid inside the shell, as well as the boundary conditions for the equality of velocities of liquid particles and the shell on their contact surfaces. An analytic expression is given for determining the distribution of the thickness component of the electric field strength, which arises due to the deformation of the shell element, depending on the frequency of oscillations of the external mechanical load. The results of numerical calculations are shown.

Processing and Modification of Ionic Polymers Metal Composites (IPMC) - A Review

This paper presents an overview of various innovative fabrication approaches and the potential applications of ionic polymer metal composites (IPMC), which is a composite material consisting of a polymer membrane sandwiched between two thin electrode layers. When given a voltage within a range of 1-5V, cations inside accompanying with water molecules of IPMC move across the width of the material causing a uniform water distribution and finally to achieve it’s bending motion. In addition to a classical processing method, three innovative modification approaches are recommended to fabricate IPMC, particularly to settle water electrolysis and leakage for multiple practical applications. Also, three applications are extensively highlighted in the later pages of the paper. This is a very new field and with the research done so far, it is believed that IPMC has a potential which is worth research elaborately. This paper presents an overview of the manufacturing components, techniques, related problems and applications of IPMC. Additionally, it recommends innovative modification fabrication approaches to subdue the associated problems in the existing conventional fabrication processing.