Summary
Artificial muscles are dielectric elastomeric system that mimic the response of natural muscle and are helpful in many bio-mimicking applications. The existing literature are based on the assumption that electrodes are compliant and are focused on materials with greater extensibility than biological matter. The present work deals with the modeling and nonlinear dynamic analysis of dielectric elastomers considering the elastomer-electrode inertia and damping for bio-mimicking. The distinguishing point is the appearance of terms related to the elastomer-electrode inertia in the governing equation. Equilibrium stretch variation exhibits cusp catastrophe and effect of electrode inertia on equilibria is examined. Single-well and double-well potential energy characteristics are obtained and equilibria's sensitiveness to initial condition and damping is illustrated by basin of attraction. Multi-frequency response exists and resonant frequency variation with geometry and inertia is presented. Time-varying voltage may lead to chaotic behavior illustrated through the bifurcation diagram and chaos is justified by the presence of strange attractor and positive Lyapunov exponent. Additionally, chaos is obtained in the case of single-well and double-well potential. The existence of similar attractors with same fractal dimension is shown. The inertia significantly changes the dynamic characteristic from chaotic to non-chaotic or vice-versa. The mechanical and electrical load may lead to chaotic or non-chaotic behavior depending on the geometry of the elastomer. Our results show that electrode inertia significantly impacts the system under quasi-static and dynamic conditions. The proposed work gives a foundation for precisely designing artificial muscle for practical applications like soft robotics, artificial arms, and prosthetic implants.
