MATHEMATICAL MODELLING AND EXPERIMENTAL CHARACTERISATION OF THE DYNAMIC RESPONSE OF DIELECTRIC ELASTOMER ACTUATORS

Abstract

Rubber like soft materials the electo-active polymers sandwiched between the complaint electrodes are known as the Dielectric Elastomer Actuators (DEAs). When the electromechanical loads are applied on the DEAs they exhibit large deformation. This technology opened the flood gate to soft machines including the biometric motions. Owing to non-linear material characteristics, electro-mechanical coupling they demand systematic efficient modeling approaches to study their behavior. Many analytical models have been investigated to study the characteristics response of the DEAs. In this thesis, we present various analytical approaches including the hyper-elastic, Visco-elastic and lumped parameters models for investigating the complex characteristics of dielectric elastomer actuators. Various type of instability may be introduced into the DEAs. The effects of prestretch of varying proportion of active to inactive area on the pull-in instability are investigated to understand the complex characteristics of Dielectric Elatomer Actuators. The threshold voltage at the initiation of dielectric breakdown is obtained analytically as well as numerically and compared with the experimental results. In addition a locus of thinning out at the vicinity of the edge is obtained applying the numerical simulations and confirmed by the experimental observations. Further, the instability parameters and their effects on the operation of DEA were explored. The DEAs exhibit different deformability levels based on the selection of materials and the approaches. A systematic scheme based on the neo-Hookean material model is applied to investigate the characteristics of DEAs applying the modulated input waveforms. Further, The comparative study of the complex behavior of DEAs applying the quasi-static, Heaviside step signal, and the modified waveform were presented. The noticeable reduction in instabilty voltage along with higher stable actuation limit were observed. Finally a qualitative comparison with the experimental validation is presented to understand the workability of the methods to be used in design and development of the time-dependent motion of the DEAs.