Modeling and simulation of the coupled mechanical-electrical response of dielectric elastomers

Dielectric elastomer (DE) is one type of electroactive polymers that can generate large strain when subjected to electrostatic field. Since first reported in late 90's, the research in this area has been intense. To allow effective design of dielectric elastomer actuators, it is necessary to have adequate analytical and numerical tools for predicting the behavior of DE actuators as well as simulating their response. In this thesis, we present a finite element model that incorporates large deformation, hyperelasticity, and electrical field-effect on dielectrics.; The fundamental concepts and underlying physics are introduced for dielectrics. Several theoretical models of electric force density are presented. Although Maxwell stress method was widely used to model dielectric elastomer, we point out that the Maxwell stress outside dielectric-dielectric boundary should also be accounted for. The predicted effect from this theory agrees very well with experimental results on acrylic elastomer.; The mechanical-electrical coupled, large deformation finite element formulation, which can be used in modeling both dielectric elastomer and ferroelectric polymer, is proposed. The formulation is based on the weak forms of Maxwell's equation and linear momentum equation expressed in the reference configuration. The closed-form consistent tangent moduli for dielectric elastomer has been derived. The numerical simulation we present demonstrates the good performance of our method in computational aspects.; Ogden model and total (Maxwell) stress method are combined to describe dielectric elastomer, together with the assumption of electrical linearity. Experimental results from uniaxial tension and constrained tension on VHB 4910 are used for fitting the material constants. Analytical analysis and numerical simulation are carried out for planner and rectangular actuators, respectively. The predicted trends are qualitatively supported by experimental results.; A global approach of digital image correlation based on the assembling technique of FEM has been developed. The method is compared with the existing local method in two experiments, the results demonstrate its speed and accuracy. Incorporated with Lagrangian mesh tracing technique, global DIC has been successfully used in shear assay experiment to measure mechanical properties of human Osteosarcoma cells. This technique can be readily used to measure deformation of EAP actuators.