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Title: An application of perturbation techniques to the vibration analysis of structures with viscoelastic coating modifications.
Creator: Kelly, William Joseph, Jr., Florida Atlantic University, Stevens, Karl K., College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
Abstract/Description: Proper application of matrix perturbation theory to the structural modification of vibrating systems yields accurate results without resolving the eigenvalue problem. For this reason it seems that the method may require less computer time and cost in performing iterative type design work. This thesis investigates the application of first-order perturbation techniques to a torsional shaft system subject to viscoelastic damping treatment modifications. The modifications are of general form in...
Show moreProper application of matrix perturbation theory to the structural modification of vibrating systems yields accurate results without resolving the eigenvalue problem. For this reason it seems that the method may require less computer time and cost in performing iterative type design work. This thesis investigates the application of first-order perturbation techniques to a torsional shaft system subject to viscoelastic damping treatment modifications. The modifications are of general form in that the coating length and thickness are not restricted. Large modifications are built up by a series of small first-order perturbations. In addition to developing a better understanding of the usefulness of this application of perturbation theory, the goal of this paper is also to understand the nonproportional damping effects of partial viscoelastic coatings.
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Date Issued: 1988
PURL: http://purl.flvc.org/fcla/dt/14455
Subject Headings: Vibration, Perturbation (Mathematics)
Format: Document (PDF)

$combined FEM-fracture mechanics analysis approach for I.C. packages$

Title: A combined FEM-fracture mechanics analysis approach for I.C. packages.
Creator: Renavikar, Ajit Anand., Florida Atlantic University, Stevens, Karl K., College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
Abstract/Description: A study of the stress distribution in and fracture behavior of the hermetic glass seal in a typical Integrated Circuit package is presented herein. Finite Element Analysis and Fracture Mechanics approaches were found effective for this investigation. A prescribed load or displacement applied at the tip of the lead protruding from the package causes high stresses at the lead-glass interface, which can lead to cracking and fracture of the seal. An approach for finding the value of the allowable...
Show moreA study of the stress distribution in and fracture behavior of the hermetic glass seal in a typical Integrated Circuit package is presented herein. Finite Element Analysis and Fracture Mechanics approaches were found effective for this investigation. A prescribed load or displacement applied at the tip of the lead protruding from the package causes high stresses at the lead-glass interface, which can lead to cracking and fracture of the seal. An approach for finding the value of the allowable load or displacement applicable at the lead tip is discussed. A correlation with a standard crack shape is presented for the 3-D model of the package. An extension of the problem revealing the effects of crack propagation on the stress intensity factor for the glass material is presented in later chapters. The J-integral method from Fracture Mechanics is found to be extremely useful for this investigation. A decline in the stress intensity factor with crack growth was observed from this study.
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Date Issued: 1989
PURL: http://purl.flvc.org/fcla/dt/14511
Subject Headings: Integrated circuits--Fracture, Fracture mechanics, Finite element method, Electronics--Materials--Fatigue
Format: Document (PDF)

Title: DEVELOPMENT OF A TWO-DIMENSIONAL LINEAR STATIC FINITE ELEMENT PROGRAM FOR A DESKTOP MICROCOMPUTER.
Creator: SCHWEET, RICHARD RAYMOND., Florida Atlantic University, Stevens, Karl K., College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
Abstract/Description: The finite element method is widely used in many areas of engineering and applied science, including structures, fluids, heat transfer, and electromagnetism. Several commercial programs exist which have extensive capabilites in these areas, but they usually require special training and mainframe computers to use. This creates a series of problems in an engineering organization because of the inefficiencies of timeshared computer systems and remote processing. These problems result in poor...
Show moreThe finite element method is widely used in many areas of engineering and applied science, including structures, fluids, heat transfer, and electromagnetism. Several commercial programs exist which have extensive capabilites in these areas, but they usually require special training and mainframe computers to use. This creates a series of problems in an engineering organization because of the inefficiencies of timeshared computer systems and remote processing. These problems result in poor productivity of the analyst. This work demonstrates the feasibility of using a desktop microcomputer to perform finite element structural analysis. A program is developed which is capable of solving two-dimensional linear static problems using truss, beam and plane stress elements. The program includes extensive pre- and post-processing capabilities and graphic displays. It allows problems with up to 500 degrees-of-freedom to be solved within a few hours and requires only about one-half hour of instruction to use. The program theory, a user's manual, and verification problems are presented.
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Date Issued: 1984
PURL: http://purl.flvc.org/fcla/dt/14225
Subject Headings: Microcomputers--Programming, Electronic data processing--Engineering
Format: Document (PDF)

Title: Effects of added components on the dynamic modeling of printed circuit boards.
Creator: Vallamattam, Bijoy Kurian., Florida Atlantic University, Stevens, Karl K., College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
Abstract/Description: Dynamic modeling of Printed Circuit Boards (PCBs) with mounted components, was investigated via the example of a PC network card by removing components in different stages and examining the resulting effects on the modal properties. Modal test results were compared with those from an ANSYS finite element analysis. Questions considered were: a) Do added components have a significant effect on the modal properties of a PCB and what are the effects ? b) How much variation is there in natural...
Show moreDynamic modeling of Printed Circuit Boards (PCBs) with mounted components, was investigated via the example of a PC network card by removing components in different stages and examining the resulting effects on the modal properties. Modal test results were compared with those from an ANSYS finite element analysis. Questions considered were: a) Do added components have a significant effect on the modal properties of a PCB and what are the effects ? b) How much variation is there in natural frequencies from board to board and test to test for a single board? c) Can a board with attached components reasonably be modeled as a uniform elastic plate with an "equivalent" density and modulus of elasticity? Results obtained indicate that added components do have significant effects on the board modal properties, less so for the lower modes than for the higher modes. There was only slight variation in the natural frequencies from board to board and from test to test for a single board. For the first two modes of vibration, it was found that the board considered could be modeled as a uniform elastic plate with "equivalent" properties, provided an appropriate value of equivalent elastic modulus was used. General findings, applicable to any PCB design, are presented.
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Date Issued: 1994
PURL: http://purl.flvc.org/fcla/dt/15015
Subject Headings: Modal analysis, Printed circuits--Mathematical models, Printed circuits--Design and construction--Data processing, Electronic systems
Format: Document (PDF)

Title: EXPERIMENTAL MODAL ANALYSIS OF A CIRCULAR PLATE WITH PARTIAL DAMPING TREATMENT.
Creator: LOPES, JAUPES BEANDAO., Florida Atlantic University, Stevens, Karl K., College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
Abstract/Description: Application of modal testing techniques in the determination of the modal parameters and mode shapes of an edge-fixed circular plate with a free-layer viscoelastic damping treatment extending over a portion of the plate surface is described. The mode shapes and modal parameters were determined for the first five flexural modes of the plate, which had a free-layer viscoelastic damping treatment on one side in the form of a central circular patch of varying size. The experimental setup and...
Show moreApplication of modal testing techniques in the determination of the modal parameters and mode shapes of an edge-fixed circular plate with a free-layer viscoelastic damping treatment extending over a portion of the plate surface is described. The mode shapes and modal parameters were determined for the first five flexural modes of the plate, which had a free-layer viscoelastic damping treatment on one side in the form of a central circular patch of varying size. The experimental setup and procedure is described in detail, with particular emphasis upon problems of modal overlap resulting from the symmetry of the test structure. Results comparing the predicted and measured natural frequencies and modal loss factors for varying degrees of damping treatment are presented for select cases.
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Date Issued: 1984
PURL: http://purl.flvc.org/fcla/dt/14223
Subject Headings: Damping (Mechanics), Mechanics, Analytic
Format: Document (PDF)

Title: IDENTIFICATION OF DISTRIBUTED STATIC LOADINGS ON BEAMS.
Creator: Shen, Sueming, Florida Atlantic University, Stevens, Karl K., College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
Abstract/Description: The problem of identification. of distributed static loadings of a one-dimensional beam is considered. All response experimental data were derived from computer simulations. True response data yield highly accurate identification of the resultant forces; the identification is, however, very sensitive to errors in the response data. The results of the experimental data are accurate within a small range of error.
Date Issued: 1986
PURL: http://purl.flvc.org/fcla/dt/14322
Subject Headings: Mechanics, Applied, Statics
Format: Document (PDF)

Title: Identification of support conditions on a beam using finite element analysis.
Creator: Ramakrishna, Suresh Babu., Florida Atlantic University, Stevens, Karl K., College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
Abstract/Description: The equivalent end deflections and rotations for beams with integral, but dissimilar, elastic supports were determined. Finite element analysis was used to generate the midsurface deflection of the beam. Numerical results were then fit to the analytical solution for the deflection of a beam, yielding the equivalent end slope resulting from deformations in the support. The lateral deflection at the support was available directly from the finite element calculation. The approach used for...
Show moreThe equivalent end deflections and rotations for beams with integral, but dissimilar, elastic supports were determined. Finite element analysis was used to generate the midsurface deflection of the beam. Numerical results were then fit to the analytical solution for the deflection of a beam, yielding the equivalent end slope resulting from deformations in the support. The lateral deflection at the support was available directly from the finite element calculation. The approach used for modeling of the supports is discussed. It was found that the slope and deflection at the support increase as the relative stiffness of the support decreases, as would be expected. Results are presented for both cantilever and beams with fixed ends, are valid for slender beams with small deflection.
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Date Issued: 1994
PURL: http://purl.flvc.org/fcla/dt/15021
Subject Headings: Girders, Finite element method, Elastic analysis (Engineering), Structural analysis (Engineering)
Format: Document (PDF)

Title: A METHOD OF ANALYSIS FOR EVALUATING THE EFFECTIVENESS OF PARTIAL DAMPING LAYER TREATMENTS FOR CIRCULAR PLATES.
Creator: SHOMSTEIN, SAMUEL COLEMAN., Florida Atlantic University, Stevens, Karl K., College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
Abstract/Description: This thesis develops an approach for predicting the loss factors and natural frequencies of circular plates with partial and complete viscoelastic damping surface treatments. Plates with fixed and simply supported edges were considered. The analysis is based on an energy approach to the free vibration of plates. Results predicted were compared with those obtained experimentally by Lopes. Both the experimental and analytical studies clearly indicate that substantial amounts of material and...
Show moreThis thesis develops an approach for predicting the loss factors and natural frequencies of circular plates with partial and complete viscoelastic damping surface treatments. Plates with fixed and simply supported edges were considered. The analysis is based on an energy approach to the free vibration of plates. Results predicted were compared with those obtained experimentally by Lopes. Both the experimental and analytical studies clearly indicate that substantial amounts of material and added weight can be saved by using partial damping surface treatments.
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Date Issued: 1985
PURL: http://purl.flvc.org/fcla/dt/14279
Subject Headings: Damping (Mechanics)--Analysis, Viscoelasticity--Experiments
Format: Document (PDF)

Title: A METHOD OF ANALYSIS FOR EVALUATING THE EFFECTIVENESS OF PARTIAL DAMPING LAYER TREATMENTS FOR SQUARE PLATES.
Creator: KUNG, CHUN-HUA., Florida Atlantic University, Stevens, Karl K., College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
Abstract/Description: An energy method for predicting the natural frequency and loss factor for square plates with partial and complete coatings is developed. Both simply-supported and edge-fixed bonndary conditions are considered. An impulse testing technique is used to provide an experimental verification of the analysis for the case of an edge-fixed square plate. The analytical and experimental results are in close agreement, and indicate that partial coatings can provide effective damping treatments.
Date Issued: 1981
PURL: http://purl.flvc.org/fcla/dt/14045
Subject Headings: Plates (Engineering)--Vibration, Damping (Mechanics)
Format: Document (PDF)

Title: Modal analysis of plates with uncertain properties: Theory and applications.
Creator: Wu, Jingshu., Florida Atlantic University, Stevens, Karl K., College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
Abstract/Description: This dissertation is concerned with modal analysis of plates with properties which vary over the structures. The uncertain geometric and material parameters are treated as random fields which are discretized over individual regions by using a local averaging technique. These discretized properties are then combined with a random perturbation procedure based upon traditional finite element methods. The result is a stochastic finite element method (SFEM) program for modal analysis of plates....
Show moreThis dissertation is concerned with modal analysis of plates with properties which vary over the structures. The uncertain geometric and material parameters are treated as random fields which are discretized over individual regions by using a local averaging technique. These discretized properties are then combined with a random perturbation procedure based upon traditional finite element methods. The result is a stochastic finite element method (SFEM) program for modal analysis of plates. This SFEM method is applied to two problems areas. The first application is to provide a new approach for modal analysis of printed circuit boards wherein the circuit board is modeled as an elastic plate with random spatial variation of its properties. The SFEM program is used to predict the effect of this variation on the natural frequencies and mode shapes of the board. Predicted results are compared with those obtained from modal testing of a circuit board. It is shown that variations between the measured and predicted modal parameters can be accounted for by small random variations in the board properties. This approach offers a simple, realistic, and cost-effective way for prediction of board modal properties. The second application is on vibration control of plates by application of surface viscoelastic damping treatments. Existing works generally treat the geometric and material properties of the damping layer as deterministic parameters, although uncertainties in the values of these parameters are commonplace. No work has been done regarding surface damping treatments with uncertain properties. In this thesis, the modal properties of plates with random spatial variation of the damping layer properties are investigated. The effects of this variation on the system natural frequencies, modal loss factors, and mode shapes are calculated by the SFEM program developed. Results are presented for a cantilever aluminum plate with complete PVC surface damping treatment with uncertain properties. In the SFEM modeling of both PC boards and plates with surface damping treatments, the effects on the system eigenvalues/eigenvectors of the correlation distance of the random property field, the correlation constant between the random fluctuations, and the magnitude of the random property variations, are investigated.
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Date Issued: 1993
PURL: http://purl.flvc.org/fcla/dt/12335
Subject Headings: Modal analysis, Stochastic processes, Finite element method, Plates (Engineering)--Testing
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.
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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)

Title: A PRELIMINARY STUDY OF WEAR OF AISI TYPE 304 STAINLESS STEEL AND MILD STEEL IN SEA WATER.
Creator: WENG, HARVEY H. L., Florida Atlantic University, Stevens, Karl K., College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
Abstract/Description: A fatigue machine was rebuilt to investigate the wear of mild steel and AISI Type 304 stainless steel while undergoing cyclic relative motions in air and sea water environments. Wear curves were obtained for both materials by measuring specimen weight loss as a function of the number of cycles of relative motion, and surface damage of the specimens was photographed. The results indicate that a sea water environment has a strong influence upon the wear characteristics of mild steel and 304...
Show moreA fatigue machine was rebuilt to investigate the wear of mild steel and AISI Type 304 stainless steel while undergoing cyclic relative motions in air and sea water environments. Wear curves were obtained for both materials by measuring specimen weight loss as a function of the number of cycles of relative motion, and surface damage of the specimens was photographed. The results indicate that a sea water environment has a strong influence upon the wear characteristics of mild steel and 304 stainless steel. For the mild steel, the corrosive effects of the sea water contributed to severe pitting and cracking of the wear surface and resulted in a significant increase in wear; after approximately 2.5 million cycles the amount of wear in sea water was approximately three times that in air. For the stainless steel, the sea water acted primarily as a lubricant and coolant, and served to reduce the amount of wear after 2.5 million cycles to about one-tenth of that in air.
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Date Issued: 1980
PURL: http://purl.flvc.org/fcla/dt/14031
Subject Headings: Steel--Fatigue--Environmental aspects, Steel, Stainless--Fatigue--Environmental aspects
Format: Document (PDF)

Title: STATIC STRESS ANALYSIS OF CHAIN LINKS USING A FINITE-ELEMENT METHOD.
Creator: TSENG, HUAN-SHOO HANS., Florida Atlantic University, Stevens, Karl K., College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
Abstract/Description: A static stress analysis of a common chain link and a pear-shaped nng ivas performed using the finite element structural analysis program SAP IV. The required finite element mesh and loading inputs were generated by the pre-processing program PRE-SAP- LINK. This procedure was used to determine the midplane stresses and displacements in a link and ring of typical sizes and subject to concentrated fcrces. Stress distributions and displacements were drawn by hand and by using a Tektronix 4662...
Show moreA static stress analysis of a common chain link and a pear-shaped nng ivas performed using the finite element structural analysis program SAP IV. The required finite element mesh and loading inputs were generated by the pre-processing program PRE-SAP- LINK. This procedure was used to determine the midplane stresses and displacements in a link and ring of typical sizes and subject to concentrated fcrces. Stress distributions and displacements were drawn by hand and by using a Tektronix 4662 Interactive Digital Plotter, respectively. The results obtained show that for both link and ring, the numerically largest principal stress and maximum in-plane shear stress occur on the element directly under an applied load . The entire procedure was verified by comparing the results obtained for the common link with experimental results in the literature and with analytical results obtained using a mechanics of materials approach. All of the results were in close agreement.
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Date Issued: 1980
PURL: http://purl.flvc.org/fcla/dt/14023
Subject Headings: Stress concentration
Format: Document (PDF)

Damping (Mechanics) (3)	+ -
Finite element method (3)	+ -
Modal analysis (2)	+ -
Perturbation (Mathematics) (2)	+ -
Plates (Engineering)--Vibration (2)	+ -

Damping (Mechanics)--Analysis (1)	+ -
Elastic analysis (Engineering) (1)	+ -
Electronic data processing--Engineering (1)	+ -
Electronic systems (1)	+ -
Electronics--Materials--Fatigue (1)	+ -
Fracture mechanics (1)	+ -
Girders (1)	+ -
Girders--Vibration (1)	+ -
Integrated circuits--Fracture (1)	+ -
Mechanics, Analytic (1)	+ -
Mechanics, Applied (1)	+ -
Microcomputers--Programming (1)	+ -
Plates (Engineering)--Testing (1)	+ -
Printed circuits--Design and construction--Data processing (1)	+ -
Printed circuits--Mathematical models (1)	+ -
Statics (1)	+ -
Steel, Stainless--Fatigue--Environmental aspects (1)	+ -
Steel--Fatigue--Environmental aspects (1)	+ -
Stochastic processes (1)	+ -
Stress concentration (1)	+ -
Structural analysis (Engineering) (1)	+ -
Vibration (1)	+ -
Viscoelasticity--Experiments (1)	+ -

College of Engineering and Computer Science (13)	+ -
Florida Atlantic University (13)	+ -
Shen, Sueming (2)	+ -
KUNG, CHUN-HUA. (1)	+ -
Kelly, William Joseph, Jr. (1)	+ -

LOPES, JAUPES BEANDAO. (1)	+ -
Ramakrishna, Suresh Babu. (1)	+ -
Renavikar, Ajit Anand. (1)	+ -
SCHWEET, RICHARD RAYMOND. (1)	+ -
SHOMSTEIN, SAMUEL COLEMAN. (1)	+ -
TSENG, HUAN-SHOO HANS. (1)	+ -
Vallamattam, Bijoy Kurian. (1)	+ -
WENG, HARVEY H. L. (1)	+ -
Wu, Jingshu. (1)	+ -

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