Vacuum-dependent electromechanical properties and failure behavior of dielectric elastomer actuators

Environmental conditions such as temperature, humidity, and pressure have a significant influence on the electromechanical performance of dielectric elastomers. In this study, motivated by potential applications in space exploration, the electromechanical behavior of dielectric elastomer actuators was experimentally investigated under vacuum environment. First, the dielectric constant was measured under atmospheric and vacuum conditions. Then, the effects of vacuum on key electromechanical characteristics, including area strain capacity, response speed, and viscoelastic creep, were experimentally characterized. Failure modes and electromechanical stability were also analyzed in detail. Compared to atmospheric conditions, the vacuum environment reduces the electro induced area strain at a given nominal electric field. However, restricted by the negative pressure, the actuator reaches its stable state significantly faster. Furthermore, because the vacuum environment notably enhances the electrical breakdown strength, the actuator can sustain much higher electric fields, ultimately achieving a larger maximum area strain before failure. In addition to conventional failure modes such as dielectric breakdown, wrinkling, and tearing, vacuum introduces unique failure mechanisms, including ionization discharge and leakage current induced actuation loss. Finally, the dynamic response tests revealed that while the vacuum environment further dampens the dynamic amplitude, the frequency dependent attenuation is predominantly governed by the intrinsic viscoelasticity of the elastomer. These findings offer important insights for the design and operation of dielectric elastomer actuator based soft robotic systems under vacuum environments, especially for future aerospace applications.