Aging setup for high cycle tests on dielectric elastomer actuators

To be implemented at the industrial scale, any dielectric elastomer actuator (DEA) must demonstrate long term reliability. For this purpose, a novel and fast DEA aging setup for high cycle tests has been developed. It monitors the in-plane strain and the change in electrode resistance of an expanding circle actuator (active area of approx. 10 mm^2) versus cycle number and drive voltage. A square voltage input signal of an amplitude up to 5 kV with resolution of 0.1% of full scale is applied to the tested actuator using a programmable high voltage supply, enabling fast switching at up to 1 kHz. The actuator mechanical output is recorded throughout the test via automated visual tracking of the edges of the top compliant electrode, from which long-time strain evolution can be inferred. The four-points-probe resistance of this electrode is measured simultaneously. This focus on the actuator electrodes allows studying their too often neglected behavior and influence on the whole DEA, as well as to optimize their formulation through comparisons between aging tests of actuators made with different electrode materials. Using this innovative, versatile, automated setup, actuator aging tests of a million of cycles can be easily performed overnight. This tool will enable dielectric elastomer actuators' industrial optimization to meet desired product technical specifications, but also in-depth academic understanding of their long-term behavior.