Computational modelling of electro-active polymers

Dal, Sinan Fırat
This study is concerned with the stability of Electro-Active Polymers (EAPs) having geometries with periodic microstructures subjected to coupled electromechanical effects. For this purpose, coupled electromechanical equations, which are nonlinear, are discretized using the Finite Element Method (FEM) under the prescribed boundary conditions. EAPs are smart materials that may undergo large mechanical deformations when subjected to an electric field. Unlike many other materials that show permanent deformations under the influence of the electric field, EAPs can return to their original shapes when the electric field is deactivated. In addition, EAPs are used in many engineering applications where robot and artificial muscle production are effective since they can respond quickly to the electrical fields to which they are exposed. In order to study the coupled electro-mechanical behavior of EAPs, two different but coupled differential equations must be solved. The governing equations of coupled electro-mechanics are introduced by the Maxwell equations for electrostatics and the conservation of linear momentum for elastostatics. These two differential equations are discretized in space by using FEM. Since the residual vector formed through discretization is still non-linear, linearization must be performed. As a result, the equation system of degrees of freedom is solved iteratively by using the Newton method. Different material models are used to analyze the coupled problem. The efficiency of the models are tested through numerical examples of benchmark problems borrowed from various references. Moreover, the developed computational model of coupled electro-mechanics is further used to analyze the behavior of porous EAPs with periodic microstructures. The effect of electro-mechanical coupling on the stability behavior of EAPs is investigated through stability analyzes in the presence of an electric field for representative geometries with periodic microstructures. It is shown that in the presence of an electric field not only the value of the critical load where the pattern transformation takes place can be shifted but also the shape of the final pattern can be totally changed.