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 222 for “"Mode Shapes"”.
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Structural Damage Detection Utilizing Experimental Mode Shapes
… through analysis of experimentally measured mode shapes?”</p> <p>The work encompasses construction of a test structure, with three braces that can be repeatedly engaged or dis-engaged, thus allowing for testing of a variety of braced configurations. For this thesis, damage is assumed to cause …
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The natural mode shapes and frequencies of graphite/epoxy cantilevered plates and shells.
Thesis. 1978. M.S.--Massachusetts Institute of Technology. Dept. of Aeronautics and Astronautics.
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Natural frequencies and an atlas of mode shapes for generally-laminated, thick, skew, trapezoidal plates
… and rotary inertia is also included.in the model. Convergence of the solution resulting from changes in spring values and number of terms in the series is investigated. The accuracy of the method is demonstrated by comparing the present method to available results for plates of various …
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Identification of Physical Changes to a Steel Frame
The thesis utilized physical testing and computer modeling to determine the feasibility of identifying a change to the mass or stiffness of a steel frame. Physical testing was performed using an accelerometer, linear shaker, and arbitrary function generator. Two methods of laboratory testing were …
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Finite Element Modeling and Active Control of an Inflated Torus Using Piezoelectric Devices
… finite element package, ANSYS, is used to model the inflated torus. The effect of torus aspect ratio and inflation pressure on the vibratory response of the structure is investigated. The interaction with the torus of the surface-mounted piezoelectric patches, made of PVDF, is modeled using …
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MOBILITY ANALYSIS AND TOPOLOGY SYNTHESIS OF COMPLIANT MECHANISM USING COMPLIANCE NUMBER AND PSEUDO-RIGID-BODY MODEL (PRBM)
… number (C) and stored strain energy, or mode shapes, are strongly correlated. This compliance number (C) concept is revisited, and a more lucid interpretation of its significance is provided. A fundamental understanding of the concept of deformation mode shapes in compliant mechanisms is …
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Reconciliation of a Rayleigh-Ritz beam model with experimental data
… modification on a structure, an analytical model which sufficiently describes the behavior of the structure must be developed. Analytical models can be generated for almost any structure, but such a model will generally not effectively predict the behavior of the structure unless the model …
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Modal Identification Using Smart Mobile Sensing Units
… civil structures is limited to the estimation mode shapes with a low spatial resolution. Modal coordinates are identified only at the location of sensors, which are fixed at particular locations on the structure. Increasing the number of sensors in the structure is an alternative to increase …
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Periodic orbit analysis of the Helmholtz equation in two-dimensional enclosures
… Keller) methods. It is also noted that some mode shapes in chaotic enclosures are scarred by the short periodic orbits. This motivates the proposal of the Mode Scar Hypothesis and the Mode Resonance Function Hypothesis.The trace formula, which is a sum over periodic orbits, approximates the …
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Assessment of lateral and torsional stiffness characteristics of medium rise concrete buildings
… of buildings to establish accurate analytical models of the structures. These measurements, for five different buildings, consisted of data on their fundamental mode shapes and natural frequencies. Initially, estimates of these characteristics were obtained by inputting traditional evaluations …
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The response of box-type structures to vibration.
… a knowledge of its natural frequencies and mode shapes and modal damping factors is required. In this work the finite-element method of analysis is used to determine the natural frequencies of vibration and the corresponding mode shapes of the box structure and computer programs were …
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Identification of singularities in the displacement field for damage detection in structures
… includes one damage localization approach using mode shapes and two damage identification methodologies based on static meas-urements. The premise is that concentrated cracks introduce singularities in the displacement fields. The first study on the detecting and locating damage using mode shapes …
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Investigation of shell and axisymmetric shell structures
… a program to analyse the natural frequencies and mode shapes of cooling towers whilst explicitly including the effects of leg supports and foundation elasticity, C. E. G. B. pub. No. RD/L/P 10/76. 2. Nelson, R. L., and Hellewell, J. S., * Vibration tests on a 1/250th scale model of Didcot cooling …
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Dynamic Testing and Modeling of a Superelevated Skewed Highway Bridge
… the frequency response functions (FRF). Eleven modes were identified with frequencies ranging from 2.75 Hz to 22.5 Hz. Mode shapes associated with each mode were constructed using the imaginary components of the FRFs. The half-power bandwidth method was used to estimate the damping for each …
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Design of a Scaled Flight Test Vehicle Including Linear Aeroelastic Effects
… in matching scaled structural frequencies and mode shapes in order to achieve consistent linear scaling of simple models. This methodology is adopted for use on a high fidelity joined-wing aircraft model. Natural frequencies and mode shapes are matched by optimizing structural ply properties …
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An investigation of the response of a 1/5-scale model of the Titan III launch vehicle to longitudinal excitation
Experimental resonant frequencies and mode shapes from vibration tests with a 1/5-scale model of the Titan III-A launch vehicle are presented, Measurements of longitudinally excited vibration modes of the model structure supported in a suspension system offering negligible restraint to longitudinal …
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The use of generalized beam theory, finite elements and experimental testing to investigate the stability of light gauge steel sections subject to axial load
… linear and non-linear analysis, buckling modes (global, distortional and local buckling) and buckling analysis methods (finite element method, finite strip method and generalized beam theory) are addressed. The literature review is concerned with computer software applications, theoretical …
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Modal Analysis of Axisymmetric Structures using Zernike Polynomials and Machine Learning
… to cabin noise, making an understanding of tire mode shapes crucial for effective vibration mitigation. Likewise, lightweight stiffened panels in electric aircraft demand careful vibration control to ensure passenger comfort. Addressing these challenges calls for innovative approaches not only to …
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Determination of axial load and support stiffness of continuous beams by vibration analysis
Three models are presented which predict frequencies and mode shapes of transverse vibration for a continuous prismatic Bernoulli-Euler beam on elastic supports, subjected to a compressive axial load. The first model, which approximates support stiffnesses by an equivalent elastic foundation, is …
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A method for the geometrically nonlinear analysis of compressively loaded prismatic composite structures
… and geometric shape imperfections can be modelled. The method can predict the nonlinear phenomena of postbuckling strength and imperfection sensitivity which are exhibited by some buckling-dominated structures. The method is computer-based and is semi-analytic in nature, making it …
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