Computational modelling of electro-active polymers

Download

index.pdf

Date

2019

Author

Dal, Sinan Fırat

Metadata

Show full item record

This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.

Item Usage Stats

321
views

134
downloads

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.

Subject Keywords

Polymers., Electro-Active Polymers (EAPs), Finite Element Method (FEM), Periodic Microstructures, Pattern Transformation.

URI

http://etd.lib.metu.edu.tr/upload/12623838/index.pdf
https://hdl.handle.net/11511/44021

Collections

Graduate School of Natural and Applied Sciences, Thesis

Suggestions

OpenMETU
Core

Nanocomposites based on blends of polyethylene Işık, Fatma; Yılmazer, Ülkü; Department of Chemical Engineering (2005) In this study the effects of compatibilizer type, organoclay type, and the addition order of components on the morphological, thermal, mechanical and flow properties of ternary nanocomposites based on low density polyethylene, LDPE were investigated. As compatibilizer, ethylene/methyl acrylate/glycidyl methacrylate, ethylene/glycidyl methacrylate, and ethylene/butyl acrylate/maleic anhydride; as organoclay Cloisite? 15A, Cloisite? 25A and Cloisite? 30B were used. All samples were prepared by a co-rotating t...
Polymerization and polymer characterization of n-vinylcaprolactam Polat, Özlem; Usanmaz, Ali; Department of Polymer Science and Technology (2005) In this study, N-vinylcaprolactam was polymerized by radiation in the solid state. The polymerization was carried out at room temperayure under vacuum and open to atmosphere respectively. The polymerization mechanism showed autoacceleration and the rate of polymerization was higher in the presence of oxygen. However the limiting conversion was 100% under vacuum conditions and 90% in the present of oxygen. This is due to the low molecular weight olgomer formation in the presence of oxygen. The polymers were ...
Pyrolysis mass spectrometric analysis of copolymer of polyacrylonitrile and polythiophene Oğuz, Gülcan; Hacaloğlu, Jale; Department of Polymer Science and Technology (2004) In the first part of this work, the structural and thermal characteristics of polyacrylonitrile, polyacrylonitrile films treated under the electrolysis conditions in the absence of thiophene, polythiophene and the mechanical mixture and a conducting copolymer of polyacrylonitrile/polythiophene have been studied by pyrolysis mass spectrometry technique. The thermal degradation of polyacrylonitrile occurs in three steps; evolution of HCN, monomer, low molecular weight oligomers due to random chain cleavages a...
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...
Nanocomposites based on recycled poly(ethylene terepthalate) Tolga, Aslı; Yılmazer, Ülkü; Department of Chemical Engineering (2005) In this study, the effects of glycol type, organoclay type and concentration on the final properties of nanocomposites based on recycled poly(ethylene terephthalate) was investigated. For this purpose, first recycled PET was glycolysed and after that unsaturated polyester-montmorillonite nanocomposites were synthesized by using three different types of glycols (i.e. ethylene glycol (EG), propylene glycol (PG) and diethylene glycol (DEG)). As the first step, all the compositions were prepared by Cloisite 30B...

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.