Computational modelling of electro-active polymers

Download
2019
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.

Suggestions

Multiscale Modeling of Thin-Wire Coupling Problems Using Hybridization of Finite Element and Dipole Moment Methods and GPU Acceleration
ÖZGÜN, ÖZLEM; Mittra, Raj; Kuzuoğlu, Mustafa (2020-01-01)
In this article, a hybrid numerical method, called finite element method (FEM) + dipole moment (DM), is presented for efficient solution of multiscale electromagnetic radiation and scattering problems that involve structures with fine features, such as thin-wire antennas or objects. In this method, the FEM is hybridized with the DM approach to help ease certain computational burdens, such as mesh refinement, ill-conditioning, memory overload, and long computation times, when solving multiscale problems with...
Numerical investigations on the hydrogen jet pressure variations in a strut based scramjet combustor
Suppandipillai, Jeyakumar; Kandasamy, Jayaraman; Sivakumar, R.; Karaca, Mehmet; Karthik, K. (2021-04-01)
Purpose – This paper aims to study the influences of hydrogen jet pressure on flow features of a strut-based injector in a scramjet combustor underreacting cases are numerically investigated in this study. Design/methodology/approach – The numerical analysis is carried out using Reynolds Averaged Navier Stokes (RANS) equations with the Shear Stress Transport k-v turbulence model in contention to comprehend the flow physics during scramjet combustion. The three major parameters such as the shock wave pattern...
Computation of transient thermal stresses in elastic-plastic tubes: Effect of coupling and temperature-dependent physical properties
Eraslan, Ahmet Nedim (2002-06-01)
The objective of this study is to obtain the transient solution of the thermoelastic-plastic deformation of internal heat-generating tubes by considering the thermomechanical coupling effect and the temperature-dependent physical properties of the material. The previously developed steady-state model describing the elastic-plastic behavior of the tubes is modified to obtain the transient solution. The propagation of the elastic-plastic interface for a given heat load is obtained; and the corresponding stres...
Nonlinear absorption behaviors of filled and unfilled d shell metal complexes of 5, 10, 15, 20-tetrakis(4-hydroxyphenyl)porphyrin
Dogan, N.; Dumanogullari, F. M.; HAYVALI, MUSTAFA; YILMAZ, HAMZA; Kurum, U.; YAĞLIOĞLU, HALİME GÜL; ELMALI, Ayhan (Elsevier BV, 2011-05-27)
We study nonlinear absorption behaviors of 5, 10, 15, 20-tetrakis(4-hydroxyphenyl)porphyrins with the central metal ions: Zn(2+), Ni(2+), Co(2+), and Fe(3+) by open aperture Z-scan technique with 65 ps or 4 ns pulse duration. For 65 ps pulse duration the filled d shell compounds exhibit nonlinear absorption while the unfilled d shell compounds exhibit saturable absorption. For 4 ns pulse duration Ni, Co and Fe compounds exhibit nonlinear absorption at high fluence while Ni compound exhibits saturable absorp...
Investigation of photovoltaic properties of amorphous InSe thin film based Schottky devices
Yilmaz, K.; Parlak, Mehmet; Ercelebi, C. (IOP Publishing, 2007-12-01)
In this study, device behavior of amorphous InSe thin films was investigated through I-V, C-V and spectral response measurements onto SnO2/p-InSe/metal Schottky diode structures. Various metal contacts such as Ag, Au, Al, In and C were deposited onto amorphous p-InSe films by the thermal evaporation technique. The best rectifying contact was obtained in a SnO2/p-InSe/Ag Schottky structure from I-V measurements, while the Au contact had poor rectification. Other metal contacts (Al, In and C) showed almost oh...
Citation Formats
S. F. Dal, “Computational modelling of electro-active polymers,” Thesis (M.S.) -- Graduate School of Natural and Applied Sciences. Civil Engineering., Middle East Technical University, 2019.