Application Cases

Experiment Title: Symmetric and Asymmetric Bistable Driving Control Experiments

Research Direction:Based on the issues of insufficient lifetime and response lag in dielectric elastomers, two solutions are proposed. One is to utilize the special nature of bistable structures, which allows for driving by simply triggering the transition between bistable states without the need for continuous loading. This results in a rapid response on the millisecond scale. The proposed solutions are experimentally verified.

Experiment Purpose:Currently, bistable driving structures of dielectric elastomers can be mainly divided into two types: separated and coupled. Although some experimental tests and exploratory studies on application scenarios have been conducted for coupled bistable driving structures, research on key technical issues such as design methods, performance characterization, and control strategies is limited. Based on this, the present experimental study, starting from the perspective of system energy, investigates the design methods, performance influencing factors, and driving mode transitions of bistable driving structures. This provides theoretical guidance and practical experience for the development of high-performance, long-lifetime dielectric elastomer actuators.

Testing Equipment:Acrylic tape, conductive carbon paste, function signal generator, and high voltage amplifier.

Experiment Process:

To verify the feasibility and correctness of the design theory and adjustment methods, two experiments were conducted on symmetric bistable structures. Three design parameter combinations were selected from the three regions shown in Figures 3-5 to fabricate bistable structures (without flexible electrodes), as shown in Figure 3-14. The results indicate that the structure can maintain an effective bistable configuration only when the design parameters L* and K* match the type regions in Figure 3-3.

Next, the driving strategy for symmetric bistable actuators was investigated. Due to the manual fabrication of bistable actuators, it is impossible to achieve perfectly symmetrical bending on both sides. Therefore, actuators with an initial stable angle difference of less than 2° on both sides were selected as symmetric bistable actuators for experimental testing.

Finally, a 6kV pulse voltage was applied to the bistable structure, and the duty cycle of the pulse voltage was continuously adjusted to observe the driving changes of the bistable structure. It was found that when the duty cycle reached 1%, the actuator could achieve mutual transitions between the two bistable states. The process was recorded using a high-speed camera, and the relationship between voltage and the actuator's change in angle was plotted, as shown in Figure 3-16.

Experimental Wiring Diagram

Experimental Results:As observed in Figure 3-16(a), when a pulse voltage with a period of 2s and a duty cycle of 1% is applied, the bistable structure undergoes rapid bistable transitions following the pulse voltage period. Figures 3-16(c) and 3-16(d) show that the time for the structure to transition from a positive angle to a negative angle is around 0.07 seconds, meaning that the deformation can be completed within 100 milliseconds. Moreover, no external voltage is required to maintain the deformation, effectively addressing the issues of response lag and the risk of electrical breakdown due to continuous voltage loading in dielectric elastomer actuators.

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