Dynamics of soft mechanical systems actuated by dielectric elastomers

A computation methodology for studying the dynamics of flexible mechanical systems containing soft actuators of dielectric elastomers is originally proposed. The absolute nodal coordinate formulation (ANCF) is used to describe the rigid-body motions and large deformations of the flexible mechanical systems. A new viscoelastic solid element of ANCF is proposed for meshing the components of dielectric elastomers. The constitutive model of dielectric elastomers is deduced from the Helmholtz free energy according to thermodynamics, and embedded into the ANCF solid element. The proposed solid element is an 8-node hexahedra element with each node represented by 12 spatial nodal coordinates and 4 electrical nodal coordinates. Both the displacement and electric fields of the continuum system are discretized and described by the proposed element with high-order functions of interpolation. The element internal forces and their Jacobians are derived. Then dynamic equations of flexible multibody systems containing components of dielectric elastomers are established and solved numerically via the generalized-alpha algorithm of time integration. Finally, numerical examples are given to validate the proposed element and the computation methodology. The experimental test is also performed, and the test results are compared with the numerical results to further validate the proposed methodology.