Mechanical Engineering Commons^™

Measurement Of Fluid Velocities In A Simulated Heat Pipe, Lewis Collin Moore

Mechanical Engineering ETDs

Velocity components of numerous geometries may be measured with the laser Doppler technique. Combinations of system parameters were investigated that were useful for constructing a two-dimensional velocimeter for a tube with porous walls. A method was developed which combined a local oscillator with a crossed-incident beam using backscatter at very small angles from the longitudinal axis. Seeding requirements, electronics signal processing, permeability measurements, and measurement point constraints were investigated. Preliminary fluid velocity results were obtained, and recommendations are made for further improvements to overcome the difficulties encountered in the current investigation.

Response Of The Lower Vertebral Column To Caudocephalad Acceleration, A. Peter Vulcan

Wayne State University Dissertations

This dissertation is concerned with the measurement of the response, in those areas of the vertebral column where fractures are most common, when the seated human is subjected to caudocephalad acceleration. Such accelerations and consequent vertebral fractures are experienced not only in ejection from aircraft, but also in survivable helicopter and aircraft crashes, and in certain types of falls. It is intended that the measurements should provide a better understanding of the mechanisms of vertebral fracture and data for the formulation of an appropriate mathematical model.

An Optimization Technique Applied To The Determination Of Orthotropic Material Properties Using Dynamic Response Test Data, Ronald L. Webster

Theses and Dissertations

A knowledge of the behavior of a material under loading similar to expected service loading is required before that material can be used effectively in the design process. Without sufficient mechanical properties data, the design process degenerates to a time consuming and often costly "build, test and modify" type of program. Obviously, this trial and error approach leaves much to be desired.

Optimization Of Physical Properties Of Hydraulic Cushion Cells For Vehicle Impact Restraint, William Evans Hughes

Theses and Dissertations

In recent years, the United States has witnessed a vast expansion of its internal highway system. Concurrently the number of vehicles has increased as has the average yearly milage per vehicle. Unfortunately, along with increased vehicle use there has been an alarming increase in annual loss of life and property due to traffic accidents. Statistics verify that the modem freeway systems greatly reduce dangerous head on collisions but the rate of accidents due to collisions with fixed objects in or near the roadway has increased almost 50 percent in the past thirty years.^1 In 1966, about 13>300 deaths were …

A Computer Procedure For The Identification Of Beam, Spring, And Damping Parameters Of An N-Mass Model Using Transient Data, Lynn A. Christiansen

Theses and Dissertations

If, however, one could develop a model for a given physical system, that is a model which can be described in terms of lumped masses, springs beams, and dashpots and then identify the parameter simply by processing acceleration data such as that obtained from drop tests or shaker tests, the task of identification is greatly simplified.

Water Injection In An Automobile Gas Turbine Combustion System, Billy Ray Jackson

Theses and Dissertations

"GENTLEMEN, JUNK YOUR ENGINES!" This title of a recent periodical article [1]* catches some of the expectation for the wedding of the Automobile and the Gas Turbine, The nuptials cannot be completed though, unless two problems are overcome: 1) high fuel consumption, and 2) high operating temperature. The first problem is solvable by the use of heat regeneration and much work has been done in this area [2][3] [4]. The solution of the second problem of high operating temperature was the basis for this thesis. The method of solution was by water injection into the combustion gases prior to entrance …

Analytical Study Of Heat Conduction And Thermal Stress In Solids With Pressure Dependent Contact Resistance, Dhruvkumar S. Patel

Theses and Dissertations

In the usual thermal stress analysis of a body, the stresses are found for a predetermined temperature distribution. In problems involving composite materials, thermal contact resistance between materials can significantly affect the temperature distribution. The contact resistance is normally a function of the contact pressure and thermally induced stresses can affect the temperature distribution. Thus in composite bodies the thermal stress problem and the heat transfer problem may be coupled and require a simultaneous solution of both problems.

A Numerical Study Of The Coanda Effect., Soloman P. Chavez

Mechanical Engineering ETDs

A numerical solution for the flow in a two-dimensional bistable fluid amplifier is obtained. A minimum Reynolds number is found below which attachment will not occur. The study shows the quality of attachment and attachment point varying with Reynolds number.

Experimental Investigation Of Submerged, Incompressible, Turbulent, Impinging Jets, David Tzeh-Hsian Lee

Theses

Measurements concerning various flow parameters of jets impinging on a smooth lucite plate and a heated metal plate have been carried out. In particular, it is shown that the potential core length of a jet is a function of the Reynolds number and of the jet diameter. It has also been demonstrated that impinging jets behave in many important respects like free jets, except in the immediate vicinity of the target plate.

The flow behavior in the wall jet zone was investigated experimentally, and a satisfactory agreement with the results of the previous investigators was found. The maximum velocity decay …

Vertical Force Measurement For The Chaparral Rocket Sled, John C. Gustafson

Mechanical Engineering ETDs

A study of the feasibility of instrumenting existing structures with strain sensing elements to measure a specific component of force transmitted by the structure in use has been conducted. A specific structure, the front slipper assembly of the Chaparral rocket sled, was used in this study. The developmental phase of this work was conducted through the use of a model study. The model studies were made to determine appropriate stress raisers and locate strain gages so the desired force component could be measured. The actual structure was modified in accordance with the results of the model tests. Calibration tests and …

Improved Numerical Techniques For Three Dimensional Transient Conduction Coupled With Surface Radiation And Variable Emissivities, Jimmie H. Smith

Mechanical Engineering ETDs

The problem of transient conduction combined with surface radiation and variable emissivities is solved numerically. The existing, but little used, multidimensional Douglas-Peaceman-Rachford alternating-direction-implicit (ADI) technique for finite differencing is chosen as the best available. It is modified and applied to the three-dimensional transient heat equation with source term. Techniques for blocking conduction in excluded directions are demonstrated. Quasi-linearization is used to combine the radiant enclosure calculations with the transient conduction calculations. That is, on an alternating basis, a time step in conduction is followed by a radiant enclosure solution. The radiant enclosure problem is solved in a novel manner, combining …

A Study Of Turbulent Heat Transfer From A Flat Plate With Transverse Temperature Variations, John C. W. Kwan

Theses and Dissertations

Heat transfer in turbulent flow from external surfaces has been investigated extensively in the past. Most of the theoretical and experimental work deals with a two dimensional boundary layer on isothermal or uniform heat flux surfaces with longitudinal temperature variation. However, little attention has ever been paid to the case in which the temperature of the plate varies transversely. This is a three dimensional problem due to the spanwise variation of the thermal boundary layer. The most elementary example of this is the boundary formed by the sudden temperature impulse that acts transversely across a flat plate as shown in …

A Digital Dynamic Data Compensation Technique, George Lee Schulz

Mechanical Engineering ETDs

The output of seismic transducers is proportional to the input only for inputs in specific frequency range. This paper presents a method for extending the usable frequency range of seismic transducers through the use of a digital data processing technique. The method is based on the assumptions that a seismic transducer may be represented by a damped single degree of freedom system and that the output of the transducer is proportional to the relative displacement between the seismic mass and the surface on which the transducer is mounted. The computational technique utilizes a new, efficient, and accurate method of numerical …

A Criterion For Dynamic Low-Cycle Shear Fracture, Teh T. Liu

Mechanical Engineering ETDs

The present investigation establishes a cumulative-damage criterion for specimens subjected to reversed cyclic dynamic shear loads. The empirical equation is found to be:

where

= the change in plastic shear strain at each loading.

= the ultimate shear strain at single loading.

= the empirical exponent to be determined.

Specimens of 6061-T6 aluminum alloy were tested under reversed shear loadings from 1 to 22 applications prior to fracture. The amount of shear deformations was measured at the center part of the critical section. The data was analyzed with the aid of a digital computer. The exponent p in the power …

An Experimental Study Of The Viscoseal Bearing, Chandrakant Khumaji Shah

Masters Theses

The experimental data obtained from two groove geometries of the viscoseal bearing were analyzed to study the bearing characteristics and the sealing performance. The experimental bearing characteristics were compared with the Dubois and Ocvirk Short-bearing Approximation. The sealing performance analysis of the bearing included (1) the determination of the sealing coefficient which was compared with the Stair and Hale method of theoretical prediction and (2) the effect of the bearing eccentricity ratio on the sealing coefficient, which was compared with the Vohr and Chow method of theoretical prediction.

The results of the study indicated that, at constant load and speed, …

Dynamic Response Of Circular Plates To Transient And Harmonic Transverse Loads Including The Effect Of Transverse Shear And Rotary Inertia, Perakatte Joseph George

Doctoral Dissertations

"Using an improved theory of plate vibration suggested by R. D. Mindlin which takes into account the effects of transverse shear and rotary inertia, free and forced transverse vibrations of uniform circular plates are studied and the results compared with those obtained using the classical theory of plate vibration. The governing equations are developed in polar coordinates using the equations of elasticity. Frequency equations for axisymmetric and antisymmetric vibrations are derived for solid circular plates under different boundary conditions and for an annular plate rigidly mounted on a shaft. The response of plates to different types of rapidly applied axisymmetric …

A Finite Element Method For Geometrically Nonlinear Large Displacement Problems In Thin, Elastic Plates And Shells, Ronald August Melliere

Doctoral Dissertations

"A finite element method is presented for geometrically nonlinear large displacement problems in thin, elastic plates and shells of arbitrary shape and boundary conditions subject to externally applied concentrated or distributed loading. The initially flat plate or curved shell is idealized as an assemblage of flat, triangular plate, finite elements representing both membrane and flexural properties. The 'geometrical' stiffness of the resulting eighteen degree-of-freedom triangular element is derived from a purely geometrical standpoint. This stiffness in conjunction with the standard small displacement 'elastic' stiffness is used in the linear-incremental approach to obtain numerical solutions to the large displacement problem. Only …

Method For Optimizing Multi-Layer Insulation, William Donald Morath

Masters Theses

"The use of multi-layer insulation can result in reduced material cost, weight, or volume. A method for selecting layer materials is described. Each layer material is selected to operate at its upper temperature limit and to contribute to the overall performance of the wall. The analyses required for optimizing flat and cylindrical walls are developed. Use of the digital computer makes it feasable [sic] to select layer materials from a large group of candidates. Fortran IV programs for optimizing flat and cylindrical walls are presented, and their use is demonstrated by the solution of example problems. Methods for improving the …

Design Of R-C-C-R Spatial Mechanism, Kao-Chien Hsei

Masters Theses

"An analysis to design a particular R-C-C-R spatial mechanism was developed using tensor notations and operations. This specific R-C-C-R spatial mechanism can be used to couple two shafts intersected at a skew angle with constant rotating speed ratio. This skew angle, or bending angle of the two shaft, may vary from 30 up to 180 degrees. The governing equations of relative positions of the mechanism were formulated as a function of two variables: the bending angle of the shafts and the rotating angle of the input link. To exemplify the various design conditions, the design parameter versus the bending angle …

The Design Of A Direct Current Generator Field Controller, Melvyn Elwin Downs

Masters Theses

"A controller was built utilizing transistors and silicon controlled rectifiers to allow torque control of the General Electric dynamometer, type TLC-50. The current gain of the controller was approximately 10⁶ such that the field current could be controlled by an input current of zero to approximately two microaaperes. The transfer function for the controller-dynamometer system was experimentally determined. The results indicate that the gain of the open loop torque control system is constant for frequencies up to 1.1 radians per second. Satisfactory values of gain for proportional and proportional plus integral control, were experimentally determined by operating the closed loop …

A Theoretical Analysis Of The Free Vibrations Of A Clamped Circular Plate With Damping, Bhalchandra Krishnaji Vaidya

Masters Theses

"A theoretical analysis of the free vibrations of a clamped circular plate was undertaken. The effects of transverse shear were considered for application to relatively thick plates in which there exist sharp transients and frequencies corresponding to higher modes. The method adopted by R. D. Mindlin was used to develope [sic] the differential equation of motion for the plate. The damping effect due to the resistance of the medium in which the plate vibrates was also considered. This damping was assumed to be due to the generation of pressure waves caused by the displacement of the plate...Since the solution requires …

The Use Of Turbulence Energy Equation In Boundary Layer Study, Ro-Chi Tai

Masters Theses

"A turbulent boundary layer problem has been studied analytically and compared with an available experiment in the literature. Correlations of the experimental data were made to investigate the validity of the commonly used empirical relations on turbulent shear stresses. It was found that the model which related the local turbulent shear stress linearly with the local turbulent kinetic energy, as used by Bradshow et. al., appeared to be most reasonable. combining this model with the expression of turbulent viscosity given by Boussinesq, it was then possible to introduce the turbulence-energy equation in addition to the governing equations of continuity and …

Experimental Determination Of Dynamic Properties Of Aluminum Including Poisson's Ratio, Terry Lee Holman

Masters Theses

"Two rods of 7075-T651 aluminum are longitudinally impacted to investigate the material's dynamic properties. The test rod, initially at rest, is instrumented with strain gages to record the strain-time history after the impact rod, accelerated to uniform velocity by an air gun launcher, strikes the test rod. A camera records the strain-time pattern displayed on an oscilloscope. The experiment indicates a consistent rise time of approximately 9 µsec. Simple one-dimensional theory correlates well with the experimental data. Compensation is included for the transverse sensitivity of the gages used. The dynamic values for both the modulus of elasticity and Poisson's ratio …

A Comparison Of Lumped Parameter Models Commonly Used To Describe One-Dimensional Vibration Problems, Suresh Kumar Tolani

Masters Theses

"Three lumped parameter model representations of the one-dimensional uniform continuous system in a vibration state are examined. The exact (continuous) solutions were used as a reference to evaluate the accuracy of the results obtained via these discrete element models. The model comparisons, carried out for both the principal modes and the systems under forced excitations, are based on the maximum strain energy. The effect of varying the number of segments in the model representation showed improvement in approximating the exact strain energy solution as the number of segments was increased. In general, the results of the model comparisons based on …

The Analysis Of R-S-S-R Spatial Four-Bar Mechanism, David Perng Chyi

Masters Theses

"Although many methods are known for the kinematic analysis of spatial mechanisms, such as descriptive geometry, vector analysis, dual number theory, matrices, screw calculus, and various other methods, a better way to analyze the specific R-S-S-R four-bar mechanism is to use tensor methods in order to eliminate the apparently formidable and tedious tasks of mathematically formulating problems and obtaining solutions. The analysis described in this paper is developed basically by using tensor notations and operations, and the calculations take advantage of the capabilities of modern digital computers. A FORTRAN program for the IBM 360 Data Processing System which will analyze …

Dynamic Response Of A Gyrocompass, Subhash Govind Kelkar

Masters Theses

"A gyrocompass with three degrees of freedom is studied and an attempt made to solve the exact equations of motion numerically. The equations are obtained by using the Lagrange formulation of the problem. The kinetic energy and the potential energy of the system are determined from the energies of the various components. These are then substituted into Lagrange's equation to obtain the three equations of motion for the three angular coordinates. As few restrictive assumptions as possible are made during this development. From these exact equations of motion an approximate analytical solution is obtained by making several assumptions and then …

Analysis Of A Water Level Control, Bhupendra Girdharlal Shah

Masters Theses

"This thesis presents the analysis of a controller for a liquid level control system. The controller was built using an analog computer providing the ability to easily construct up to three modes of control. The controllers analyzed were: 1.) Proportional, 2.) Proportional plus reset, and 3.) Proportional plus reset plus preact. The system was tuned experimentally to provide satisfactory operation and root loci were also plotted to show the system stability for the three modes"--Abstract, page ii.

Film Boiling From Inclined Flat Surfaces, Charles Ernest Price

Masters Theses

"The object of this investigation was to determine the effect of inclination on the heat transfer for saturated film pool boiling from a flat plate heater. Nitrogen at atmospheric pressure was used as the test fluid. The test plate was oriented at various angles from the horizontal position and the convective film coefficient was determined for each angle. Tests were conducted for heater angles of 0°, 30°, 60°, and 90°. The heater strip was placed in a container of the liquid and was heated electrically. Heat transfer results were obtained for plate temperatures ranging from 100 to 800°F. As the …

A Computerized Method For Finding The Dynamic Response Of Multi-Mass Systems With Damping To Arbitrary Inputs, Bakulesh Balbhadra Patel

Masters Theses

"A practical procedure for the systematic application of Foss's method to the solution of multi-degree-of-freedom damped systems is presented. It is relatively easy to determine the response of classically damped systems to various inputs. For non-classically damped systems the method proposed by K. A. Foss has been employed. This method gives an exact and complete solution for the response of linear multi-mass damped systems subjected to arbitrary inputs. Since the method requires lengthy and complex computations, the use of a digital computer is essential. In order to obtain the complete response of a multi-mass damped system to both sinusoidal and …

Apparatus And Techniques For The Plane Wave Analysis Of Acoustic Filters, Victor Hugo Simon

Masters Theses

"This thesis describes a method for determining the reflection and transmission characteristics of acoustic filters under static (i.e. no flow) conditions. These characteristics are obtained by the combination of linear plane wave acoustic theory with a sequential experimental procedure. The experimental data necessary for the calculation of the reflection characteristics were obtained from measurements made on the inlet side of the filter with a standing wave tube apparatus. In order to calculate the transmission characteristics of the filter, the standing wave measurements were augmented with measurements taken on both the inlet and outlet side of the filter. This was accomplished …