An anomalous dynamic phenomenon—unforeseen thickness elongation in biaxially prestretched dielectric elastomer actuators (DEAs) under sinusoidal voltage excitation—is investigated here. Unlike quasi‐static predictions where the material remains compressed throughout the cycle, this phenomenon exhibits alternating compression and elongation within each period, accompanied by higher harmonics and complex phase‐portrait trajectories. A lumped‐parameter nonlinear vibration model attributes this to “inertial detuning,” defined as the coupling of inertial force with prestretch‐induced geometrical nonlinear stiffness. Notably, this behavior does not occur in non‐prestretched DEAs even when inertial effects are considered, confirming that it arises from the synergistic coupling between prestretch and inertia rather than from inertia alone. Combined parameter analysis and experimental comparison elucidate the control laws of the prestretch ratio and excitation parameters, showing that prestretching dually enhances performance and induces detuning in DEA dynamic design. The proposed model is supported by experimental measurements and preliminary numerical verification using the vector finite element method (VFIFE), both of which show a consistent trend in overall dynamic behavior. These findings provide crucial support for developing high‐performance, high‐reliability DEA dynamic systems.
Wu et al. (Thu,) studied this question.