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(1 - 6 of 6)
- Title
- Hybrid method of finite element and photoelasticity to analyze stress concentrations on threaded cylinders.
- Creator
- Gonella, Julio Cesar., Florida Atlantic University, Case, Robert O.
- Abstract/Description
-
This paper studies the stress concentrations at the root of the threads of a cylinder. A photoelastic analysis using the stress freezing procedure is used to calculate the stress along the cylinder and the stress concentrations at the root of the threads. These values are compared to that of similar cylinders with different threaded configurations. A finite element model is built by using the photoelastic data to find a suitable load distribution along the threaded region. The finite element...
Show moreThis paper studies the stress concentrations at the root of the threads of a cylinder. A photoelastic analysis using the stress freezing procedure is used to calculate the stress along the cylinder and the stress concentrations at the root of the threads. These values are compared to that of similar cylinders with different threaded configurations. A finite element model is built by using the photoelastic data to find a suitable load distribution along the threaded region. The finite element model predicted results similar to the photoelastic analysis and showed a method of reducing the stress concentrations on the threads by redesigning a pressure ring on the cylinder.
Show less - Date Issued
- 1990
- PURL
- http://purl.flvc.org/fcla/dt/14581
- Subject Headings
- Stress concentration, Cylinders
- Format
- Document (PDF)
- Title
- AN ANALYTICAL STUDY OF THE DYNAMIC CHARACTERISTICS OF TOWED FLEXIBLE CYLINDERS.
- Creator
- KOMROWER, JEFFREY MARC, Florida Atlantic University
- Abstract/Description
-
A linear differential equation of motion to describe the fluid-induced vibrations of a towed flexible cylinder, with applications toward towed array system, is developed. The equation is explored for its free vibration characteristics with the aid of a computer program. The behavior of the locus of the several lowest eigenfrequencies, as system parameters were varied revealed the basic dependence of the system on these parameters. It is shown that for various combinations of system parameters...
Show moreA linear differential equation of motion to describe the fluid-induced vibrations of a towed flexible cylinder, with applications toward towed array system, is developed. The equation is explored for its free vibration characteristics with the aid of a computer program. The behavior of the locus of the several lowest eigenfrequencies, as system parameters were varied revealed the basic dependence of the system on these parameters. It is shown that for various combinations of system parameters, the system may be subject to buckling or oscillatory instabilities in its lower flexural modes. It was found that (1) longer cylinders are more susceptible to oscillatory instabilities than are shorter cylinders but are less susceptible to buckling, (2) tension due to skin friction drag stabilizes the system, and (3) the tail of the cylinder acts as an initiator of unstable motions. Nomographs are presented to predict natural frequencies for various combinations of system parameters.
Show less - Date Issued
- 1979
- PURL
- http://purl.flvc.org/fcla/dt/13978
- Subject Headings
- Cylinders--Testing
- Format
- Document (PDF)
- Title
- Experimental study of flow over a bundle of cylinders.
- Creator
- Khuc, Hiep Hieu., Florida Atlantic University, Su, Tsung-Chow, College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
- Abstract/Description
-
The drag reduction by vortex fusion was investigated. A comparison of flow over a bundle of cylinders in uniform and in disturbed currents was performed in a water channel. The model was subjected to cross flow. A thin cylindrical wire located nearby upstream and leveled at half the height of the test model was used as a source of disturbance. A hydrogen bubble technique was utilized to observe the flow pattern. The accumulation of vortices at stagnating regions in front of a bundle of...
Show moreThe drag reduction by vortex fusion was investigated. A comparison of flow over a bundle of cylinders in uniform and in disturbed currents was performed in a water channel. The model was subjected to cross flow. A thin cylindrical wire located nearby upstream and leveled at half the height of the test model was used as a source of disturbance. A hydrogen bubble technique was utilized to observe the flow pattern. The accumulation of vortices at stagnating regions in front of a bundle of cylinders transformed into a counter-rotated curl at leading edges of each leading cylinder in the bundle. Measurements were carried out by a computerized data acquisition system. Drag coefficient measurements, digital spectral and fourier analyses were also performed. Results have shown that a drag reduction can be obtained by introducing a thin cylindrical wire in front of the stagnation.
Show less - Date Issued
- 1994
- PURL
- http://purl.flvc.org/fcla/dt/15026
- Subject Headings
- Vortex-motion, Fluid dynamics, Cylinders, Fourier transformations, Hydrodynamics
- Format
- Document (PDF)
- Title
- Analysis of a composite fiber wrapped gas cylinder for deep diving submersibles.
- Creator
- Clark, A. M., Harbor Branch Oceanographic Institute
- Date Issued
- 1986
- PURL
- http://purl.flvc.org/fau/fd/FA00007433
- Subject Headings
- Pressure vessels--Testing, Gas cylinders, Oceanographic submersibles, Johnson-Sea-Link II (Submarine)
- Format
- Document (PDF)
- Title
- An experimental study of vortex response during cutting by a blade or cylinder.
- Creator
- Krishnamoorthy, Srikanth., Florida Atlantic University, Marshall, Jeffrey S., College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
- Abstract/Description
-
An experimental study of the vortex response to interaction with and cutting by a thin flat plate or circular cylinders of various diameters has been performed. The direction of motion of the flat plate (or circular cylinder) is normal to the vortex axis in the experiments. The vortex is generated by withdraw of fluid at an orifice at the bottom of an "inner cylinder" immersed in a rectangular tank, and the flow field is visualized with both water soluble and immiscible dyes. In the...
Show moreAn experimental study of the vortex response to interaction with and cutting by a thin flat plate or circular cylinders of various diameters has been performed. The direction of motion of the flat plate (or circular cylinder) is normal to the vortex axis in the experiments. The vortex is generated by withdraw of fluid at an orifice at the bottom of an "inner cylinder" immersed in a rectangular tank, and the flow field is visualized with both water soluble and immiscible dyes. In the experiments with circular cylinders, the bending of the vortex is compared to computational predictions from [15], and the mechanism of subsequent breakup of the vortex as it gets closer to the cylinder is studied. The vortex is observed to bend farther without breakup for larger forward speeds of the circular cylinder. Very little bending is observed when the vortex interacts with the flat plate, except for angles of attack exceeding the stall limit Following cutting of the vortex by the flat plate or circular cylinder, a vortex shock is observed to form and propagate up the vortex axis. No vortex shock is observed on the opposite side of the blade. The various forms of these vortex shocks have been photographed, and they appear very similar to travelling vortex breakdowns. The propagation speed of the shocks is compared to an analytical solution for instantaneous vortex cutting by a flat plate of zero thickness.
Show less - Date Issued
- 1993
- PURL
- http://purl.flvc.org/fcla/dt/14977
- Subject Headings
- Vortex-motion, Blades--Noise, Cylinders, Rotors (Helicopters), Helicopters--Noise
- Format
- Document (PDF)
- Title
- Mobility power flow (MPF) approach applied to fluid-loaded shells with ring discontinuities.
- Creator
- McCain, Thomas Scott., Florida Atlantic University, Cuschieri, Joseph M., College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
- Abstract/Description
-
The vibrational and acoustic characteristics of fluid-loaded, cylindrical shells with single or multiple, aperiodically-spaced ring discontinuities are studied using an approach based on the mobility power flow (MPF) method and a hybrid numerical/analytical method for the evaluation of the velocity Green's function of the shell. The discontinuities are associated with internal structures coupled to the shell via ring junctions. The approach is a framework allowing alternative shell and/or...
Show moreThe vibrational and acoustic characteristics of fluid-loaded, cylindrical shells with single or multiple, aperiodically-spaced ring discontinuities are studied using an approach based on the mobility power flow (MPF) method and a hybrid numerical/analytical method for the evaluation of the velocity Green's function of the shell. The discontinuities are associated with internal structures coupled to the shell via ring junctions. The approach is a framework allowing alternative shell and/or internal structure models to be used. The solution consists of the net vibrational power flow between the shell and internal structure(s) at the junction(s), the shell's velocity Green's function, and the far-field acoustic pressure. Use of the MPF method is advantageous because the net power flow solution can be used as a diagnostic tool in ascertaining the proper coupling between the shell and internal structure(s) at the junction(s). Results are presented for two canonical problems: an infinite, thin cylindrical shell, externally fluid-loaded by a heavy fluid, coupled internally to: (1) a single damped circular plate bulkhead, and (2) a double bulkhead consisting of two identical damped circular plates spaced a shell diameter apart. Two excitation mechanisms are considered for each model: (1) insonification of the shell by an obliquely-incident, acoustic plane wave, and (2) a radial ring load applied to the shell away from the junction(s). The shell's radial velocity Green's function and far-field acoustic pressure results are presented and analyzed to study the behavior of each model. In addition, a comparison of these results accentuates the qualitative difference in the behavior between the single and multiple junction models. When multiple internal structures are present, the results are strongly influenced by inter-junction coupling communicated through the shell and the fluid. Results are presented for circumferential modes n = 0 & 2. The qualitative differences in the results for modes n = 0 and n = 2 (indicative of all modes n > 0ified in the far-field acoustic pressure and velocity Green's function response with the characteristics of the shell and internal plate bulkhead. The results for the single junction model demonstrate the significance of the shell's membrane waves on the reradiation of acoustic energy from the shell; however, when multiple junctions are present, inter-junction coupling results in a significant broad acoustic scattering pattern. Using the results and analysis presented here, a better understanding can be obtained of fluid-loaded shells, which can be used to reduce the strength of the acoustic pressure field produced by the shell.
Show less - Date Issued
- 1996
- PURL
- http://purl.flvc.org/fcla/dt/12490
- Subject Headings
- Shells (Engineering)--Vibration, Cylinders--Vibration, Fluid dynamics, Sound--Transmission
- Format
- Document (PDF)
