Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 34 for “"Experimental Modal Analysis"”.
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An attempt to quantify errors in the experimental modal analysis process
Experimental modal analysis (EMA) techniques have become a popular method of studying the dynamic characteristics of structures. A survey of literature available reveals that experimental modal models resulting from EMA may suffer from inaccuracy due to a host of reasons. Every stage of EMA could …
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Improved approaches to the indirect force determination problems via experimental modal analysis
Solving the inverse problem, finding the applied forces knowing the system characteristics and the response, has been a difficult problem in structural dynamics. Insufficient accuracy in the system identification and uncorrelated content in the response exacerbate the ill-conditioned nature of the …
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A precision laser scanning system for experimental modal analysis: its test and calibration
… been widely used for dynamic measurements and experimental modal analysis. A laser scanning system that provides position accuracy, speed, and flexibility plays a key role in this technique. This thesis gives an overview of various laser scanning techniques and the requirements of a laser …
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Development of a laser-based automated mechanical mobility measurement system for one-dimensional experimental modal analysis
… of frequency response functions (FRFs) for experimental modal analysis where one-dimensional structural motion predominates. With this system FRFs are measured and recorded in a format that is readily imported into a popular modal analysis software. A scanning laser Doppler velocimeter is …
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Diagnostic test and analytical methods for resolving fan/motor vibration problems in air-conditioning units
… objective of this thesis is to develop test and analysis procedures to revise ASHRAE Standard 87.1 Standard for small (<36 in. diameter) propeller fans. Test and analysis procedures also need to be used to convert AHRAE Standard 87.1 - 1992 test results where the fan hub mobility is zero to …
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Experimental and Analytical Examination of Golf Club Dynamics
… has spurred the need for advanced scientific analysis using a variety of techniques. Among the most prevalent of these methods are finite element analysis and experimental modal analysis, and use of these techniques in examining a golf club is the focus of this research. The primary goals of …
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Using Vibration Analysis to Determine Refrigerant Levels In an Automotive Air Conditioning System
… automobile. In the research presented, vibration analysis is examined as a possible method to determine this R-134a amount. Initial laboratory tests were completed and experimental modal analysis methods were investigated. This approach is based on the hypothesis that the natural frequency of the …
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Configuration Validation of a Novel In-Space Propellant Storage and Transfer System
… and dynamic stability, mass gauging and CFD analysis of the rotational propellant transfer method in space. The application of this technology in Low Earth Orbit (LEO) and Geo-Synchronous Orbit (GEO) would enable further extending the mission capabilities of modern day Commercial Launch …
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Output-Only Experimental Modal Testing of Large Residential Structures and Acoustic Cavities Using Sonic Booms
In this thesis, an output-only experimental modal testing and analysis technique known as the Natural Excitation Technique (NExT) is examined for use with large residential structures and interior cavities. The technique which assumes a random, stationary input causing the response data is reviewed …
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Fluid-structural interaction effects on vibrations of pipework.
… of structural pipework and investigates the modal responses. The emphasis of this study has been focused on assessing the effects that a fluid has upon the vibratory characteristics of the system concerned. The work elicits both theoretical and experimental investigations into the previously …
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The experimental characterization of the dynamics of a reciprocating freon compressor system
This thesis discusses the experimental modal analysis work done on a reciprocating Freon compressor. The primary goal of this work was to aid in the development of a dynamic finite element model for the compressor. The crankcase, the compressor shell, and the entire compressor were each studied …
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The effects of ambient temperature variations on structural dynamic characteristics
… recent years. As a consequence, the accuracy of experimental data, which is often used to validate and update finite element models, has become extremely important. However, as researchers have attempted to identify and quantify sources of error in the experimental modal analysis (EMA) process, …
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High resolution modal analysis using poles obtained at a single location
… proposed to increase the spatial resolution of experimental modal analysis results so that the resolution of the results is typical of that found in finite element modelling. The fixed-poles procedure estimates the structure’s poles from a high frequency density, driving point frequency response …
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Vibration behaviour of pre-stressed precast hollow core floor with concrete topping thickness and boundary condition
… stiffness. The preliminary study on prediction analysis is performed to determine a testing location. Two-floor areas (Area A and Area B) was selected, and a modal vibration analysis was compared from experimental modal analysis (EMA) and Finite Element Analysis (FEA) by using SAP2000 software …
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Computational Modal Analysis Of A Half-Scale Business Jet Fuselage Tail Section
… be known. This may be accomplished by performing modal analysis to derive those relevant properties. For a business jet, an important location of study for vibration is the tail section, as it supports the engine which is a primary source of structure-borne noise. The objective of this research is …
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Damage detection methodology for composite UAV wings using modal analysis and probabilistic concepts
… to structural health monitoring and analysis techniques. This necessitates research into a methodology for practical and effective structural health monitoring techniques. This work presents a methodology for structural health monitoring and particularly delamination detection in …
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A numerical and experimental investigation of vibratory bowl feeders
… the model were compared with those obtained from experimental modal analysis. There was good agreement for the first three natural frequencies. Differences in the higher frequency modes indicated an overconstrained model which could be accounted for by the flexural vibration of the bowl; iii) A …
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Multiple Reference Impact Testing of Bridges Using a Network of Low-Cost Dynamic Exciters
… Reference Impact Testing (MRIT) is a form of Experimental Modal Analysis (EMA) that can be used to identify the dynamic properties of full-scale bridges. These dynamic properties include natural frequencies, mode shapes, damping ratios, modal scaling and modal flexibility. Since these system …
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A theoretical and experimental study of modal interactions in metallic and laminated composite plates
This dissertation focuses on nonlinear modal interactions in plates. Our first investigation involved the activation of a two-to-one internal resonance in the response of a metallic cantilever plate. Although the plate was excited around the frequency of its second bending mode, its response …
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