Nonlinear free vibration analysis of ionic liquid enhanced soft composite membrane

Due to their electromechanical coupling properties, ionic liquid (IL)-enhanced dielectric elastomer composites are promising for applications in soft robotics and implantable actuators. However, their structural vibration behaviors subjected to electric fields remain unclear. This work investigates the nonlinear vibration of IL-enhanced soft composite (ILESC) membranes subjected to electric loading through theoretical modeling and numerical simulation. The effective properties of ILESC membrane are determined by a developed micromechanical model considering the physical mechanisms as involved. Governing equations for the nonlinear vibration of a pre-stretched circular membrane made of ionic liquid/poly (dimethylsiloxane) (IL/PDMS) are established, which are solved by Taylor series expansion (TSE) and differential quadrature (DQ) methods. The developed model and numerical results are verified by comparing present results to existing studies and finite element analysis. The influences of the size of the membrane, the direct current (DC) voltage and alternating current (AC) frequency of the electric field, and the attributes of the IL fillers and matrix on the nonlinear vibration of the structure are investigated. The voltage-induced nonlinearity is highly sensitive to the content, size and shape of the IL fillers. The performances of the structure within various AC frequency bands can be tuned by changing the geometry of the IL fillers as well as the surface charge density of the matrix. This study aims to provide guidelines for predicting and optimizing the structural behaviors of ILESC membranes, accelerating their applications in engineering demanding flexibility and voltage-dependent responses.