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Title:Advanced finite-element techniques for simulation of composite materials and large-scale scattering problems
Author(s):Zhang, Kedi
Director of Research:Jin, Jianming
Doctoral Committee Chair(s):Jin, Jianming
Doctoral Committee Member(s):Geubelle, Philippe H.; Goddard, Lynford L.; Gong, Songbin; Schutt-Ainé, José E.
Department / Program:Electrical & Computer Eng
Discipline:Electrical & Computer Engr
Degree Granting Institution:University of Illinois at Urbana-Champaign
Subject(s):computational electromagnetics
generalized finite element method
domain decomposition method
hybrid method
parallel computing
radar cross-section
shape optimization
large-scale simulation
Abstract:This dissertation aims at developing sophisticated finite-element based numerical algorithms for efficient electromagnetic modeling and design of composite materials, fast frequency-domain scattering analysis of electrically large problems on massive parallelized computers, and efficient broadband analysis of resonant waveguide structures. To these ends, first, an interface-enriched generalized finite-element method (IGFEM) is introduced for electromagnetic analysis of heterogeneous materials. To avoid using conformal meshes, the method assigns generalized degrees of freedom at material interfaces to capture the discontinuities of the field and its derivatives, and maintains the same level of solution accuracy and computational complexity as the standard FEM based on conformal meshes. The fixed mesh nature combined with an analytical sensitivity analysis significantly reduces the computational cost in gradient-based shape optimization. Second, an efficient parallelization strategy is proposed for the domain decomposition based dual-primal finite-element tearing and interconnecting (FETI-DP) algorithm. Load balancing, global, neighboring, inter-processor communication minimization, and preconditioning techniques are adopted to improve the computational and parallel efficiency. An inhomogeneous truncation boundary condition is presented to enable the FETI-DP simulation of a stratified medium. The parallel FETI-DP algorithm is also combined with a fast near- to far-field transformation and a linear interpolation technique for efficient vectorial field imaging of electrically large objects. Finally, a hybrid technique that consists of the time- and frequency-domain computations and model-order reduction strategy is developed for the efficient simulations of resonant waveguide structures. Numerous results are presented to demonstrate the accuracy, efficiency, and capability of the proposed methods.
Issue Date:2018-01-02
Rights Information:Copyright 2018 Kedi Zhang
Date Available in IDEALS:2018-09-04
Date Deposited:2018-05

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