Boundary element-finite element acoustic analysis of coupled domains

İrfanoğlu, Bülent
This thesis studies interactions between coupled acoustic domain(s) and enclosing rigid or elastic boundary. Boundary element-finite element (BE-FE) sound-structure interaction models are developed by coupling frequency domain BE acoustic and FE structural models using linear inviscid acoustic and elasticity theories. Flexibility in analyses is provided by discontinuous triangular and quadrilateral elements in the BE method (BEM), and a rectangular plate and a triangular shell element in the FE method (FEM). An analytical formulation is developed for an extended fundamental sound-structure interaction problem that involves locally reacting sound absorptive treatment on interior elastic boundary. This new formulation is built upon existing analytical solutions for a configuration known as the cavity-backed-plate problem. Results from developed analytical formulation are compared against those from independent BE-FE analyses. Analytical and BE-FE analysis results for a selection of cavity-plate(s) interaction cases are given. Single- and multi-domain BE analyses of cavity-Helmholtz resonator interaction are provided as an alternative to modal method of acoustoelasticity. A discrete-form of the existing BE acoustic particle velocity formulation is presented and demonstrated on a basic case study. Both the existing and the discretized BE acoustic particle velocity formulations could be utilized in acoustic studies. A selection of case studies involving fundamental configurations are studied both analytically and computationally (by BE or BE-FE methods). These studies could provide a basis for benchmark case development in the field of acoustics.


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Ağar, Kartal Şahin; Koç, Seyit Sencer; Department of Electrical and Electronics Engineering (2007)
This thesis investigates analysis and simulation of the backscattering enhancement phenomenon from randomly distributed point scatterers. These point scatterers are randomly distributed within a cube or a sphere and then the backscattering enhancement phenomenon from both cubical and spherical distributions are examined throughout the thesis. The general characteristic differences between cubical and spherical distribution about the scattering phenomenon are observed. T-matrix method is used for analytic in...
Analysis of pulse diversity in radar systems
Keçelioğlu, Umut; Koç, Seyit Sencer; Department of Electrical and Electronics Engineering (2006)
In this thesis, the pulse diversity technique in radar systems in high clutter environments is investigated. In this technique, different pulse compression methods are used in each pulse in the transmitted burst to increase the unambiguous range. In pulse diversity, the design of filters used in the receiver is as important as designing the transmitted waveform. At the output of pulse-burst filter that processes pulse-by-pulse, as many channels as the pulses in the burst occur. Each of these channels is mat...
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In this paper, we propose a novel frequency domain state-space identification method for switching linear discrete time-periodic (LDTP) systems with known scheduling signals. The state-space identification problem of linear time-invariant (LTI) systems has been widely studied both in the time and frequency domains. Indeed, there have been several studies that also concentrated on state-space identification of both continuous and discrete linear time-periodic (LTP) systems. The focus in this study is the fam...
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Azizoğlu, Nursen; Geban, Ömer; Department of Secondary Science and Mathematics Education (2004)
The purpose of this study was to investigate the effects of conceptual change oriented instruction accompanied by demonstrations and gender on tenth grade students̕ understanding of gases concepts, and attitudes toward chemistry. Hundred tenth grade students from two classes taught by the same teacher in a public high school were enrolled in the study in the Fall semester of 2003-2004. Control group students were taught by traditionally designed chemistry instruction (TI), while experimental group students ...
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Akçay, Didem; Öktem, Hakan; Department of Scientific Computing (2005)
Inference of regulatory networks has received attention of researchers from many fields. The challenge offered by this problem is its being a typical modeling problem under insufficient information about the process. Hence, we need to derive the apriori unavailable information from the empirical observations. Modeling by inference consists of selecting or defining the most appropriate model structure and inferring the parameters. An appropriate model structure should have the following properties. The model...
Citation Formats
B. İrfanoğlu, “Boundary element-finite element acoustic analysis of coupled domains,” Ph.D. - Doctoral Program, Middle East Technical University, 2004.