From first cycle to fatigue: in-situ damage evolution and lifetime of dielectric elastomer actuators with continuous carbon fiber reinforcement

Dielectric elastomer actuators present unique challenges for durability studies due to small tensile forces, large strokes, and high cycle counts. Previously unfeasible with conventional testing equipment, a custom fatigue setup has recently facilitated repeatable, preload‑free installation and consistent high‑cycle testing. With the aim of obtaining viable fatigue data for silicone‑based DEAs with continuous carbon fiber reinforcement, production methods were developed that yield samples with material‑sample characteristics and minimize manufacturing artefacts. To shift the cycles to failure into an experimentally accessible range, precise notching was introduced. Edge‑notched samples, representing realistic edge‑induced defects of strip actuators, showed a pronounced scatter in cycles to failure. In contrast, center‑notched samples preserved the material‑sample character and provided apparent narrower distributions and higher average lifetimes. In both configurations, characteristic deviations from an initially quasi‑logarithmic softening were identified as promising precursors to imminent failure. Damage initiation and progression were characterized in situ using stereo digital image correlation alongside passive thermography. The combined mechanical and optical analyses yield an assessment of damage evolution and inform possible future design measures, and the transfer to state‑of‑health monitoring concepts for DEAs with continuous fiber reinforcement.