Dielectric elastomer actuators (DEAs) can undergo substantial deformation in response to an applied electric field. They are often used as artificial muscles in soft robotic system. Our work focuses on the modellig and simulation of such DEAs using both, beam and shell models. The governing equations representing electromechanical coupling in geometrically exact beams and shells are formulated in a variational setting, where a consistent derivation of the electromechanically coupled balance equations is developed from continuum theory. The dielectric elastomer beam is used as a compliant actuator in optimal control problems for multibody dynamics. Different deformations are generated by the actuating potential. To this end, different electric boundary conditions are imposed on the beam. Additionally, contact interaction is represented in the model via unilateral constraints. In the optimal control problem, an objective function is minimized while the electromechanically coupled dynamic balance equations for the flexible multibody system have to be fulfilled together with the complementarity conditions for the contact and boundary conditions.