Current Search: Girders--Vibration (x)
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- Title
- ANALYSIS OF FREE VIBRATIONS OF BEAMS WITH VARYING DEGREES OF UNCONSTRAINED VISCOELASTIC DAMPING LAYER COVERAGE.
- Creator
- DE AGUIAR, JOAO BATISTA., Florida Atlantic University, Dunn, Stanley E.
- Abstract/Description
-
A method of analysis addressing the problem of predicting the performance of beams with viscoelastic damping layer coating of varying degrees of coverage undergoing free vibrations is presented. Results based on this analysis and using mechanical properties of selected materials are generated for five different boundary conditions. The analytical results are verified experimentally for the case of a clamped-free beam. Also the main hypotheses employed in the theoretical approach are verified....
Show moreA method of analysis addressing the problem of predicting the performance of beams with viscoelastic damping layer coating of varying degrees of coverage undergoing free vibrations is presented. Results based on this analysis and using mechanical properties of selected materials are generated for five different boundary conditions. The analytical results are verified experimentally for the case of a clamped-free beam. Also the main hypotheses employed in the theoretical approach are verified. Finally, an analysis of the results leads to a discussion of the dynamic properties of coated beams.
Show less - Date Issued
- 1982
- PURL
- http://purl.flvc.org/fcla/dt/14097
- Subject Headings
- Viscoelasticity, Girders--Vibration
- Format
- Document (PDF)
- Title
- Deterministic, stochastic and convex analyses of one- and two-dimensional periodic structures.
- Creator
- Zhu, Liping., Florida Atlantic University, Lin, Y. K., Elishakoff, Isaac, College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
- Abstract/Description
-
The periodic structures considered in the dissertation are one-dimensional periodic multi-span beams, and two-dimensional periodic grillages with elastic interior supports. The following specific topics are included: (1) Deterministic Vibration--Exact solutions are obtained for free vibrations of both multi-span beams and grillages, by utilizing the wave propagation concept. The wave motions at the periodic supports/nodes are investigated and the dispersion equations are derived from which...
Show moreThe periodic structures considered in the dissertation are one-dimensional periodic multi-span beams, and two-dimensional periodic grillages with elastic interior supports. The following specific topics are included: (1) Deterministic Vibration--Exact solutions are obtained for free vibrations of both multi-span beams and grillages, by utilizing the wave propagation concept. The wave motions at the periodic supports/nodes are investigated and the dispersion equations are derived from which the natural frequencies of the periodic structures are determined. The emphasis is placed on the calculation of mode shapes of both types of periodic structures. The general expressions for mode shapes with various boundary conditions are obtained. These mode shapes are used to evaluate the exact dynamic response to a convected harmonic loading. (2) Stochastic Vibration--A multi-span beam under stochastic acoustic loading is considered. The exact analytical expressions for the spectral densities are derived for both displacement and bending moment by using the normal mode approach. Nonlinear vibration of a multi-span beam with axial restraint and initial imperfection are also investigated. In the latter case, the external excitation is idealized as a Gaussian white nose. An expression for the joint probability density function in the generalized coordinates is obtained and used to evaluate the mean square response of a multi-span beam system. (3) Convex Modeling of Uncertain Excitation Field--It is assumed that the parameters of the stochastic excitation field are uncertain and belong to a multi-dimensional convex set. A new approach is developed to determine the multi-dimensional ellipsoidal convex set with a minimum volume. The most and least favorable responses of a multi-span beam are then determined for such a convex set, corresponding to a stochastic acoustic field. The procedure is illustrated in several examples.
Show less - Date Issued
- 1994
- PURL
- http://purl.flvc.org/fcla/dt/12366
- Subject Headings
- Grillages (Structural engineering), Girders--Vibration, Wave-motion, Theory of, Vibration
- Format
- Document (PDF)
- Title
- A perturbation method for the vibration analysis of beams and plates with free-layer damping treatments.
- Creator
- Shen, Sueming, Florida Atlantic University, Stevens, Karl K., College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
- Abstract/Description
-
The feasibility of using structural modification techniques to determine the effect of added viscoelastic damping treatments on the modal properties of a distinct eigenvalue system and a degenerate system is investigated. Linear perturbation equations for the changes introduced into the system eigenproperties are derived and applied to several examples involving the flexural vibration of beams and square plates with varying degrees of damping treatment. Both large and small perturbations are...
Show moreThe feasibility of using structural modification techniques to determine the effect of added viscoelastic damping treatments on the modal properties of a distinct eigenvalue system and a degenerate system is investigated. Linear perturbation equations for the changes introduced into the system eigenproperties are derived and applied to several examples involving the flexural vibration of beams and square plates with varying degrees of damping treatment. Both large and small perturbations are considered. An FEM code has been developed to compute the dynamic system parameters which are subsequently used in an iterative method to determine the modal properties. The perturbation approach described can accommodate temperature and frequency-dependent material properties, and the procedures involved are illustrated in the examples considered. Results obtained for these examples are compared with those available from closed form or finite element solutions, or from experiments. Excellent agreement of the results of the present method with those of other contemporary methods demonstrates the validity, overall accuracy, efficiency and convergence rate of this technique. The perturbation approach appears to be particularly well suited for systems with temperature and frequency dependent material properties, and for design situations where a number of damping configurations must be investigated.
Show less - Date Issued
- 1989
- PURL
- http://purl.flvc.org/fcla/dt/12239
- Subject Headings
- Girders--Vibration, Plates (Engineering)--Vibration, Perturbation (Mathematics), Damping (Mechanics)
- Format
- Document (PDF)