Experimental Investigations on the Out-of-Plane Sub-harmonic Vibration of a Circular Dielectric Elastomer Actuator

Dielectric elastomers have found interesting applications in soft loudspeakers, where vibrations subject to alternating electrical excitations are the key features. Although there are many theoretical studies on the nonlinear vibrations of dielectric elastomers subject to electromechanical coupling loads, the systematic experimental research is rare. In this work, we design a simple experimental setup to observe the out-of-plane vibrations of a circular dielectric elastomer actuator. We find that the dielectric elastomer has different response modes including the harmonic, super-harmonic and sub-harmonic responses at different excitation frequencies. We analyze the responses by using the short-time Fourier transformation. We find that the equivalent voltage and the AC/DC ratio are the main parameters affecting the occurrence of sub-harmonic responses. The phenomenon of mode shift is also observed in our experiments. These experimental observations provide a deeper understanding of the dynamic responses of dielectric elastomer subject to electromechanical loads.