Engineering Mechanics Commons^™

The Eccentric Disc Pitter Planter-A Soil Conservation Tillage Tool For Mechanized Farming., J Dumelow

Tanzania Journal of Engineering and Technology (TJET)

A planting technique which could enhance agricultural production is presented. The Edip planting technique which is discussed has low capital and operating costs. It also has reasonable and reliable yields as well as providing effective moisture and soil conservation.

Hydraulic Rams For Rural Water Supply Schemes In Selected Areas In Tanzania, T Mbwette

Tanzania Journal of Engineering and Technology (TJET)

This paper presents one of the many efforts made by the Faculty of Engineering and the Institute of Production Innovation of the University of Dar es Salaam towards the realization of the International Water Supply and Sanitation Decade. Special reference is made to the use of hydraulic rams along with some simple water treatment methods. Besides the account of theoretical and practical work done to-date in the field of water supply, a further evaluation of the theoretical model presented is recommended so as to enable a judgement of the present hydraulic ram designs to be done. Tests on a typical …

Shape Optimization For Elastic Hollow Bars In Torsion, Jahau Lewis Chen

Mechanical & Aerospace Engineering Theses & Dissertations

The problem of finding optimal cross-sectional shapes of elastic hollow bars in torsion is formulated and solved numerically. A variational formulation for the state equation is presented, and the material derivative of continuum mechanics is used for the shape design sensitivity analysis. Performance criteria include the bending stiffness, the torsional rigidity, and the weight of the bar. The existence of a keyway, an example of geometric irregularity, can be considered as well. The material can be either isotropic or anisotropic. The finite element method is used for the numerical solution of the variational state equation and is integrated into an …

Finite Element Thermal-Structural Analysis Of Cable-Stiffened Space Structures, Ajay Kumar Pandey

Mechanical & Aerospace Engineering Theses & Dissertations

Finite element thermal-structural analyses of cable-stiffened space structures are presented. A computational scheme for calculation of prestresses in the cable-stiffened structures is also described. The determination of thermal loads on orbiting space structures due to environmental heating is described briefly. Three finite element structural analysis techniques are presented for the analysis of prestressed structures. Linear, stress stiffening and large displacement analysis techniques are investigated.

The three techniques are employed for structural analysis of prestressed cable structures at different prestress levels. The three analyses produce similar results at small prestress. but at higher prestress differences between the results become significant. For …

Design Of A Combustion System Simulating Waste Heat Recovery From Diesel Engine Exhaust Gases, Nikolaos Papadopoulos

Mechanical & Aerospace Engineering Theses & Dissertations

A forced-draft laboratory combustion system simulating diesel engine exhaust gas volume flow rate and temperature conditions for waste energy recovery is analyzed and discussed. The system consists of a fan which supplies the air. The slightly compressed air is then ducted through a combustor where it is heated, and then to an air-quencher where it is cooled to a desired temperature. Finally, the air is sent through a heat exchanger, after a diffuser process, for waste heat recovery.

A gas dynamic analysis has been performed for each component part as well as a parametric study via a computer program in …

The Use Of Complex Versus Normal Modes In Structural Model Improvement, Chih Lin

Mechanical & Aerospace Engineering Theses & Dissertations

In the past, normal modes approximation to complex modes was employed by most researchers or users in the process of identification or modification of structural systems. This is true, of course for simple structures with no or proportional damping. For complex structures with nonproportional damping, even level of which is small, it will be shown that applying this approximation is inadequate. Use of complex modes instead of approximated normal modes is justified.

An algorithm is presented that computes a set of normal modes from the corresponding measured complex modes. The computed normal modes are then used in the Berman's technique …

Large Amplitude Free Flexural Vibrations Of Laminated Composite Plates Of Arbitrary Shape, Mo-How Shen

Mechanical & Aerospace Engineering Theses & Dissertations

A finite element formulation is presented for analyzing large amplitude free flexural vibrations of symmetrically laminated composite plates of arbitrary shape. Linear and nonlinear fundamental frequencies are determined from the analysis. The laminates are made of multiple generally or specially orthotropic layers and symmetrically disposed about the middle surface, hence there is no coupling between bending and extension. Linearized stiffness equations of motion governing large amplitude oscillations of laminates, linear element stiffness matrix, quasi-linear geometrical element stiffness matrix, and solution procedures are presented. The linearized geometrical stiffness matrix for a 18 degrees-of-freedom high precision triangular anisotropic plate element is evaluated …

Application Of Least-Squares Method To The Determination Of Orthotropic Elastic And Photoelastic Constants, R. G. Chermahini

Mechanical & Aerospace Engineering Theses & Dissertations

A least-squares technique is developed in matrix form to determine orthotropic elastic and photoelastic constants. Orthotropic elastic constants are determined by mounting strain gages on a half-plane specimen which is subjected to a compressive concentrated force. Strain values corresponding to a 1000 lb load and coordinates of the points where the gages are located are used as input data to the governing equation of orthotropic elasticity for the model under consideration. Orthotropic photoelastic constants are determined using a transparent composite half-plane model which is subjected to a concentrated load. Photoelastic constants are determined using the coordinates of selected point on …

Development Of A Friction Element For Metal Forming Analysis, W. D. Webster, Robert L. Davis

Mechanical and Aerospace Engineering Faculty Research & Creative Works

A three-dimensional finite element friction element has been developed. The friction element has been used in the analysis of round-to-square forward extrusion.Comparison with some limited experimental data is presented. © 1982 by ASME.

A Mathematical Model Used In Conjunction With A Finite Element Analysis To Aid In The Design And Analysis Of Bourdon Tubes, R. C. Weber, Robert L. Davis

Mechanical and Aerospace Engineering Faculty Research & Creative Works

A mathematical model that describes a variety of Bourdon tube geometries has been used for the three-dimensional analysis of Bourdon tubes. The variation of the stresses and tip deflections with respect to the variables used in the mathematical model are then presented as an aid in the design and analysis of the Bourdon tube. The finite element program represents a user-orientated package for calculation of tip deflections and stresses. Stresses and deflections are compared to both strain gage data and instrumented tip deflections as well as published data to establish the credibility of both the model and computer program. © …

Photoelastic Investigation Of Load Transfer In Eccentrically Loaded Single Lap Joints, Stephen Antrim Hann

Mechanical & Aerospace Engineering Theses & Dissertations

Photoelastic models of three eccentrically loaded single lap joints were analyzed. The adherends of each joint were identical and the bondlines differed in thickness and material properties. The adherends were analyzed for both cylindrical plate behavior and geometrical nonlinearity and the load transfer efficiency was examined. For all three models it was found that over 98% of the shank behaves as a cylindrical plate and that a geometrically nonlinear analysis yields bending stresses substantially lower than a linear analysis and that a relatively thick, low modulus bondline can increase load transfer efficiency.

Low Speed Handling Characteristics Of A Supersonic Transport By Eigenstructure Assignment, Michael Peter Lazar

Mechanical & Aerospace Engineering Theses & Dissertations

A synthesis procedure, based upon optimal regulator theory and eigenvalue/eigenvector assignment technique, was used in the design of a low-speed lateral control system for the SCAT-15F supersonic transport. Emphasis was placed on reducing the lateral acceleration at the pilot's station. Control laws were designed to make the aircraft handling characteristics acceptable with the exception of the lateral acceleration. It was found that a compromise between the roll performance requirements and the peak lateral acceleration requirement is needed for a successful SCAT-15F design.

Goertler Instability In Compressible Boundary Layers Along Curved Surfaces With Suction And Cooling, Alok K. Verma

Mechanical & Aerospace Engineering Theses & Dissertations

The Goertler instability of the laminar compressible boundary layer flows along concave surfaces is investigated. The linearized disturbance equations for the three-dimensional, counter-rotating streamwise vortices in two dimensional boundary layers are presented in an orthogonal curvilinear coordinates. The basic approximation of the disturbance equations, that includes the effect of the growth of the boundary layer, is considered and solved numerically. The effect of compressibility on critical stability limits, growth rates, and amplitude ratios of the vortices is evaluated for a range of Mach numbers for Oto 5. The effect of wall cooling and suction of the boundary layer on the …

An Apparatus For Measuring The Thermal Conductivity Of Cast Insulation Materials, Christine A. Wilkins, Robert L. Ash

Mechanical & Aerospace Engineering Faculty Publications

A steady-state apparatus has been developed for measuring the thermal conductivity of cast materials. The design has employed a novel thermal symmetry arrangement which can permit total electrical isolation of the test material from its surroundings. © 1980 American Institute of Physics

The Significance Of Peel Stresses In Cyclic Debonding, Richard A. Everett Jr.

Mechanical & Aerospace Engineering Theses & Dissertations

One of the possible failure modes in adhesively bonded joints is cyclic debonding -- progressive separation of the adherends by cyclic failure of the adhesive bond. In this study cyclic debonding in an adhesively bonded crack-lap shear specimen has been investigated by means of a linear elastic finite-element analysis and a series of constant­ amplitude axial fatigue tests. The primary purpose of this study was to test the hypothesis that cyclic debonding is due largely to tensile peel stresses in the adhesive.

The results of this study have indicated that not all of the tensile peel stresses in the adhesive …

The Efficiency Of A Two-Edged Tool And Its Improvement, J. R. Masuha

Tanzania Journal of Engineering and Technology (TJET)

Abstract

Steel Making In Port Talbot Works Of British Steel Corporation, S. P. Mosha

Tanzania Journal of Engineering and Technology (TJET)

Abstract

Split-Set Rock Bolt Analysis, Robert L. Davis

Mechanical and Aerospace Engineering Faculty Research & Creative Works

A system of twelve equations have been developed for the elastic-plastic analysis of split-set roof bolts and these equations have been programmed for solution on the IBM 370/168 computer. Typical solutions have been presented in graphical form for comparison with experimental data. The results compare favorably for most of the split-sets providing the system parameters are properly specified. It appears that this analytical solution will be valuable to mining engineers since the solutions have been put in graphical form. Plots of the effects of the various parameters (material strength, material strain-hardening, friction, thickness, radius, angle of contact) on the holding …

Studies Of Fracture And Deformed Surfaces Of High Strength Aluminum Alloys By X-Ray Diffraction, Tamma K. Kumar

Mechanical & Aerospace Engineering Theses & Dissertations

X-ray observations of fatigue fracture and deformed surfaces of 7075-T6 aluminum were conducted in this study. The (111) and (222) diffraction peaks were obtained from the fractured and deformed surfaces. It was observed that in comparison with the base metal, the fracture exhibited line broadening similar to that due to cold working. The broadening is indicative of plastic deformation in the vicinity of the advancing crack tip during the fracture process. Also the different regions of fracture exhibited varying degrees of line broadening. With respect to the fatigue crack, the slow crack growth region showed a greater broadening, and, hence, …

Temperature And Time Dependent Viscosity Of An Elastomer Modified Epoxy Resin, Woodrow Williard Wagner Jr.

Mechanical & Aerospace Engineering Theses & Dissertations

Temperature effects on the viiscosity of an epoxy resin (diglycidyl ether of bisphenol A - DGEBA), an elastomer (carboxy terminated butadiene acrylonitrile - CTBN), and two blends containing nominally 10 percent elastomer were examined from strain rates of 0.1 sec^-1 to 10,000 sec-¹ over a temperature range from 300K to 450K. All results indicated the greatest drop in viscosity occurred for each of the materials over the temperature range of 300K to 350K. In addition, the materials exhibited Newtonian responses over the entire strain rate range, Adding small amounts of elastomer to the I epoxy only moderately effected …

Development Of A Quadratic Finite Element Solution Of The Convective-Transport Equation., David A. Dillard

Masters Theses

"A quadratic finite element has been developed for the solution of the general three-dimensional convective-transport equation. Inherent instabilities in the numerical solution arise when the convective terms in the governing equation become significant. An application of upwinding techniques to the 20 degree of freedom serendipity element failed to produce acceptable results. Upwinding was applied to the 27 degree of freedom Lagrangian element with good results. Results of the latter element are given for several problems, including a model of a round to round metal forming process"--Abstract p. iii

Investigations Of Inertia Effects On An Infinite Solid Cylinder Due To Thermal Shock, Roland Vanderbilt Williams

Retrospective Theses and Dissertations

In this paper the effects of inertia are explored for the case of a thermal excitation applied on the surface of an infinitely long, solid circular cylinder. The linear uncoupled field equations for a homogeneous, isotropic, thermoelastic medium are used to derive the desired field equations of stress and displacement. The solution procedure included, first, the determination of the thermal boundary value problem from the energy equation which is identically satisfied for the uncoupled condition. Secondly, substitution of the strain-displacement relationships and the previously obtained thermal relation into the equilibrium equation containing inertial effects. The equilibrium equation is the only …

Effect Of Compliant Wall Motion On Turbulent Boundary Layers, Dennis M. Bushness, Jerry N. Hefner, Robert L. Ash

Mechanical & Aerospace Engineering Faculty Publications

A critical analysis of available compliant wall data which indicated drag reduction under turbulent boundary layers is presented. Detailed structural dynamic calculations suggest that the surfaces responded in a resonant, rather than a compliant, manner. Alternate explanations are given for drag reductions observed in two classes of experiments: (1) flexible pipe flows and (2) water-backed membranes in air. Analysis indicates that the wall motion for the remaining data is typified by short wavelengths in agreement with the requirements of a possible compliant wall drag reduction mechanism recently suggested by Langley. Copyright © 1977 American Institute of Physics.

Installation Induced Stresses For Grouted Roof Bolts, R. N. Nitzsche, Charles J. Haas

Mechanical and Aerospace Engineering Faculty Research & Creative Works

The judicious use of roof bolts in stabilizing underground openings necessitates the ability to determine the state of stress in and around such bolts. A method of modeling a system of roof bolts is presented. This method is then applied in the determination of the state of stress due to bolt tightening. Two specific roof bolt configurations are considered: a fully grouted post-tensioned bolt and a post-tensioned bolt with grouted-end anchorage. The analysis showed that the grout annulus transferred nearly all of the bolt load 3nto the rock within a distance of 12 hole diameters from the point of bolt …

Industrial Projects Recommended By The Faculty Of Engineering Udsm, W Kreuser

Tanzania Journal of Engineering and Technology (TJET)

During the assessment of the manuscript, it was observed that the paper does not include an abstract. The document proceeds directry to the main content without providing a separate abstract that summarize the study's objectives, methodology, key findings and conclusions

Plough Parts Production At Ubungo Farm Implements, F Kavishe

Tanzania Journal of Engineering and Technology (TJET)

During the assessment of the manuscript, it was observed that the paper does not include an abstract. The document proceeds directry to the main content without providing a separate abstract that summarize the study's objectives, methodology, key findings and conclusions

Deformation Of A System Of Clamped Thin Circular Plates With Liquid Filled Interspace., Archie Forrest Gatrost

Masters Theses

"In this work the behavior of a system of thin, circular clamped plates with liquid-filled interspace in a variable pressure environment was investigated. Six plates separated by liquid-filled chambers were arranged in alternate layers in a clamping device and a pressure was applied on one side of the six plate system. The deformation of each plate and the pressure distribution from the high pressure to low i i pressure side was measured. The plate deformation was measured by a strain gage attached at the apex of each plate and the chamber pressure by a strain gage pressure transducer.

The results …

Stability Of Filled Cylindrical Shell Columns, Yu Wen Tsao

Masters Theses

"This experimental investigation was conducted to study the stability of filled cylindrical shell columns. Two kinds of filler materials, flower clay (florist clay) and silica sand, were investigated. The cylindrical shells were made of 2024-T3 Reynolds aluminum tubing. Uniaxial compressive loading was applied directly to the filler materials through two loading rams, one at each end of the cylinder, (no loading was applied directly to the shell). Tests for investigating the load transmitting characteristics of the filler materials were performed, and the states of the stresses existing in the cylindrical shells were then obtained.

The buckling formula for thin-walled cylindrical …

Investigation Of An Energy Absorbing Device For Passenger Safety, Prakash Krishnaswamy

Masters Theses

"Energy absorption by driving an oversized plunger through a longitudinally slit shell has been studied. The characteristics obtained by conducting several runs indicate that such a system could be used for energy absorption and for limiting the force required to drive the plunger through the shell. The characteristics can be readily altered by changing the dimensions of the tube. Details of the experimental set-up have been given.

Such an absorber has been adapted for mitigating injury sustained by the occupants in the interior of a colliding vehicle. Full advantage has been taken of the "Ride down" potential available to the …

Finite-Element Analysis Of Pressure Vessels, Robert L. Davis, H. Dean Keith

Mechanical and Aerospace Engineering Faculty Research & Creative Works

The finite-element technique has been applied in the analysis of a variety of pressure vessel problems. The example problems described in this paper suggest that the finite element method is perhaps the most suitable means currently available for obtaining quick and accurate solutions for real-life pressure vessel problems. Finite-element programs can be used by the practicing engineer. Companion programs are available that can be used to check the input data and graphically display both the input and output data. © 1972 by ASME.