Current Search: Viscoelasticity (x)
View All Items
- 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
- DETERMINATION OF VISCOELASTIC MATERIAL PROPERTIES USING TWO-DIMENSIONAL PLATE TESTING.
- Creator
- UHLAR, DAVID ANDREW., Florida Atlantic University, Dunn, Stanley E., College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
- Abstract/Description
-
A method of analysis is presented which employs a two-dimensional plate test to determine the dynamic modulus of elasticity and loss factor of viscoelastic damping materials. This method is based on an energy approach to the free vibration of plates. The results derived from the two-dimensional plate test procedure are compared to values from conventional beam tests. This comparison indicates that the material properties determined from the plate test method are in good agreement with values...
Show moreA method of analysis is presented which employs a two-dimensional plate test to determine the dynamic modulus of elasticity and loss factor of viscoelastic damping materials. This method is based on an energy approach to the free vibration of plates. The results derived from the two-dimensional plate test procedure are compared to values from conventional beam tests. This comparison indicates that the material properties determined from the plate test method are in good agreement with values determined from the beam test method. Thus, the dynamic modulus of elasticity and loss factor of viscoelastic damping materials can be determined from either beam or plate tests and these values can be used in the two-dimensional plate equations to evaluate the effectiveness of the damping material. In light of this study, it is suggested that beam tests be performed to derive viscoelastic material properties because of the simplicity of the beam test procedure compared to that of the plate test procedure.
Show less - Date Issued
- 1982
- PURL
- http://purl.flvc.org/fcla/dt/14096
- Subject Headings
- Elastic plates and shells, Viscoelasticity
- Format
- Document (PDF)
- Title
- Dynamic response and stability of viscoelastic structures by interval mathematics.
- Creator
- Duan, Dehe., Florida Atlantic University, Elishakoff, Isaac
- Abstract/Description
-
It is demonstrated in this thesis that the interval mathematics is a powerful tool to deal with uncertain phenomena especially when the uncertainty in bounded. In this thesis, we apply interval mathematics to several engineering problems, apparently for the first time in the world literature. The following topics are included: (1) The application of interval mathematics in several applied mechanics problems. A brief review of basis concepts is given, and some problems are presented to...
Show moreIt is demonstrated in this thesis that the interval mathematics is a powerful tool to deal with uncertain phenomena especially when the uncertainty in bounded. In this thesis, we apply interval mathematics to several engineering problems, apparently for the first time in the world literature. The following topics are included: (1) The application of interval mathematics in several applied mechanics problems. A brief review of basis concepts is given, and some problems are presented to illustrate the application of interval mathematics. (2) The stability and dynamic response of viscoelastic plate are studied. The effect of viscoelastic parameters on critical velocity is elucidated. (3) The application of Qiu-Chen-Elishakoff theorem in uncertain string and beam problems is investigated.
Show less - Date Issued
- 1994
- PURL
- http://purl.flvc.org/fcla/dt/15090
- Subject Headings
- Interval analysis (Mathematics), Viscoelasticity, Fractional calculus
- 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.
Show less - Date Issued
- 1985
- PURL
- http://purl.flvc.org/fcla/dt/14279
- Subject Headings
- Damping (Mechanics)--Analysis, Viscoelasticity--Experiments
- Format
- Document (PDF)
- Title
- Enhancement of spike and stab resistance of flexible armor using nanoparticles and a cross-linking fixative.
- Creator
- Lambert, Vincent., College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
- Abstract/Description
-
A novel approach has been introduced in making flexible armor composites. Armor composites are usually made by reinforcing Kevlar fabric into the mixture of a polymer and nanoscale particles. The current procedure deviates from the traditional shear thickening fluid (STF) route and instead uses silane (amino-propyl-trimethoxy silane) as the base polymer. In addition, a cross-linking fixative such as Glutaraldehyde (Gluta) is added to the polymer to create bridges between distant pairs of...
Show moreA novel approach has been introduced in making flexible armor composites. Armor composites are usually made by reinforcing Kevlar fabric into the mixture of a polymer and nanoscale particles. The current procedure deviates from the traditional shear thickening fluid (STF) route and instead uses silane (amino-propyl-trimethoxy silane) as the base polymer. In addition, a cross-linking fixative such as Glutaraldehyde (Gluta) is added to the polymer to create bridges between distant pairs of amine groups present in Kevlar and silated nanoparticles. Water, silane, nanoparticles and Gluta are mixed using a homogenizer and an ultra-sonochemical technique. Subsequently, the admixture is impregnated with Kevlar - bypassing the heating and evaporating processes involved with STF. The resulting composites have shown remarkable improvement in spike resistance; at least one order higher than that of STF/Kevlar composites. The source of improvement has been traced to the formation of secondary amine C-N stretch due to the presence of Gluta.
Show less - Date Issued
- 2009
- PURL
- http://purl.flvc.org/FAU/186769
- Subject Headings
- Armor, Design and construction, Composite materials, Testing, Nanoparticles, Testing, Viscoelasticity
- Format
- Document (PDF)
- Title
- Determination of the tensile strength of the fiber/matrix interface for glass/epoxy & carbon/vinylester.
- Creator
- Totten, Kyle, Carlsson, Leif A., Florida Atlantic University, College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
- Abstract/Description
-
The tensile strength of the fiber/matrix interface was determined through the development of an innovativetest procedure.Aminiature tensile coupon with a through-thickness oriented, embedded single fiberwas designed. Tensile testing was conducted ina scanning electron microscope (SEM)while the failure process could be observed.Finite element stress analysis was conducted to determine the state of stressat the fiber/matrix interface in the tensile loaded specimen, and the strength of the...
Show moreThe tensile strength of the fiber/matrix interface was determined through the development of an innovativetest procedure.Aminiature tensile coupon with a through-thickness oriented, embedded single fiberwas designed. Tensile testing was conducted ina scanning electron microscope (SEM)while the failure process could be observed.Finite element stress analysis was conducted to determine the state of stressat the fiber/matrix interface in the tensile loaded specimen, and the strength of the interface.Test specimensconsistingof dry E-glass/epoxy and dry and seawater saturatedcarbon/vinylester510Awere preparedand tested.The load at the onset of debondingwascombined withthe radial stressdistributionnear thefree surface of the specimento reducethe interfacial tensile strength. For glass/epoxy, was 36.7±8.8MPa.For the dryand seawater saturated carbon/vinylester specimensthetensilestrengthsof the interface were 23.0±6.6 and 25.2±4.1MPa, respectively.The difference is not significant.
Show less - Date Issued
- 2015
- PURL
- http://purl.flvc.org/fau/fd/FA00004415, http://purl.flvc.org/fau/fd/FA00004415
- Subject Headings
- Composite materials -- Mechanical properties, Composite materials -- Testing, Fibrous composites -- Mechanical properties, Polymeric composites -- Mechanical properties, Viscoelasticity
- Format
- Document (PDF)
- Title
- Convex identification and nonlinear random vibration analysis of elastic and viscoelastic structures.
- Creator
- Fang, Jianjie, Florida Atlantic University, Elishakoff, Isaac, College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
- Abstract/Description
-
This dissertation deals with the identification of boundary conditions of elastic structures, and nonlinear random vibration analysis of elastic and viscoelastic structures through a new energy-based equivalent linearization technique. In the part of convex identification, convex models are utilized to represent the degree of uncertainty in the boundary condition modification. This means that the identification is actually the identification of the convex model to which the actual boundary...
Show moreThis dissertation deals with the identification of boundary conditions of elastic structures, and nonlinear random vibration analysis of elastic and viscoelastic structures through a new energy-based equivalent linearization technique. In the part of convex identification, convex models are utilized to represent the degree of uncertainty in the boundary condition modification. This means that the identification is actually the identification of the convex model to which the actual boundary stiffness profile belongs. Two examples are presented to illustrate the application of the method. For the beam example the finite element analysis is performed to evaluate the frequencies of a beam with any specific boundary conditions. For the plate example, the Bolotin's dynamic edge effect method, generalized by Elishakoff, is employed to determine the approximate natural frequencies and normal modes of elastically supported isotropic, uniform rectangular plates. In the part of nonlinear random analysis, first a systematic finite element analysis procedure, based on the element's energy formulation, through conventional stochastic linearization technique, is proposed. The procedure is applicable to a wide range of nonlinear random vibration problem as long as element's energy formulations are presented. Secondly, the new energy-based stochastic linearization method in finite element analysis setting is developed to improve the conventional stochastic linearization technique. The entire formulation is produced in detail for the first time. The theory is applied to beam problem subjected to space-wise and time-wise white noise excitations. Finally, the new energy-based stochastic linearization technique is applied to treat nonlinear vibration problems of viscoelastic beams.
Show less - Date Issued
- 1996
- PURL
- http://purl.flvc.org/fcla/dt/12467
- Subject Headings
- Elasticity, Viscoelasticity, Structural dynamics--Mathematical models, Vibration--Mathematical models
- Format
- Document (PDF)