Mechanical and Aerospace Engineering electronic theses and dissertations (MU)
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The items in this collection are the theses and dissertations written by students of the Department of Mechanical and Aerospace Engineering. Some items may be viewed only by members of the University of Missouri System and/or University of Missouri-Columbia. Click on one of the browse buttons above for a complete listing of the works.
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Item Pressure and velocity fields in the Sondhauss tube(University of Missouri--Columbia, 1969) Mentesana, Charles Phillip"Scope of the Present: Investigation The pressure and velocity fields along the length of the oscillator are investigated experimentally for different heater power inputs. Pressure and velocity magnitudes are measured. Frequency of, and phase relation ships between, pressure and velocity at points along the length of the oscillator are presented. An investigation of the velocity profile, produced by the interaction of the oscillating gas with the atmosÂphere, at the exit of the oscillator is made. Finally, a correlation between the accumulation of dust in discrete piles on the bottom inside surface of the tube and the predicted air particle displacement is made. All measurements of dust particle displacement, velocity, pressure, frequency and phase relationships will be compared to the quarter-standing wave occurring in a resonant organ pipe."--Page 9.Item Multiaxial creep models for 304 stainless steel(University of Missouri--Columbia, 1985) Xiao, Dayan; Cho, Uee WanTwo viscoplastic constitutive equations were developed to describe creep strain of 304 stainless steel at 593 [degrees] C (1100 [degrees] F) under variable stresses of pure tension, pure torsion and combined tension and torsion. One was based on isotropic strain hardening concept and the other employed a state variable (kinematic strain hardening). The creep equations and the constants were determined from constant stress creep test data. The stress dependence of time dependent creep component was best described by a hyperbolic sine function of the maximum shear stress above a transition point and a linear relation below it. Comparing theoretical calculations with experimental data, the constitutive equations gave reasonable predictions of the material responses.Item Simulation of electronic circuit board assembly(University of Missouri--Columbia, 1987) Wanbaugh, L. D.; Blundell, J. K.This thesis describes the development of a generic simulation system for the Simulation of Manufacturing (SIMAN) simulation language. This project included the use of a line balance optimization scheme and a program, written in BASIC, that will write the SIMAN experiment file for the user's specific application. This experiment file is then combined with a universal model file to produce a simulation file. The simulation can process a system that has fifty separate operations, five different products and ten stations. While generic in nature, the simulation scheme was prepared with printed circuit board assembly in mind. Included are sample runs demonstrating the application of the simulation system.Item Fatigue growth of surface flaws in finite plates(University of Missouri--Columbia, 1981) Tortoriello, Vicente; Jolles, Mitchell"The most commonly observed structural defect is the surface crack. The primary difficulty in analyzing the growth of surface cracks is the stress intensity factor which varies from point to point along the crack due to crack front curvature and the complex local geometry. The study of surface cracks started in 1950, where Green and Sneddon [1] characterized the distribution of stress in the neighborhood of a flat elliptical crack in an elastic solid. The first surface crack experiments to be reported were conducted independently at the Naval Research Laboratory [2], and at Douglas Aircraft Company [3] in 1960. In 1962 a technique for making shallow cracks in sheet metals was performed by Yen and Pendleberry [4]. The analysis of surface crack data according to fracture mechanics principles was made possible by Irwin [5] in the same year. Paris and Sih [6] in 1964, attempted to improve the applicability of Irwin's estimate of the stress intensity factor for plates of finite thickness by means of analogies to existing two dimensional solutions. Randall [7] in 1966 studied the effect of crack size and shape on apparent plane strain fracture toughness values. He also used crack opening displacement measurements as qualitative indicators of crack tip deformation phenomena. F. W. Smith [8] in this year investigated the problem of a semicircular surface crack by the finite difference numerical method. Ayres [9] applied a finite difference elastoplastic solution to one semi-elliptical surface crack geometry in 1968. Hall [10] in 1970 compared apparent fracture toughness values from surface crack specimens, with those obtained from other specimen types. Miyamoto, Miyoshi, Levy and Marcal [11] presented a finite element analysis for specific geometries. Marrs and Smith [12] presented a method of determining stress intensity factors in epoxy models by three dimensional photoelasticity in 1971. Corn [13] studied cracking techniques for obtaining partial thickness cracks of pre-selected depths and shapes in the same year. In 1972 Cruse [14] analyzed a semi-circular surface crack using boundary integral equations. F. W. Smith [15] performed the elastic analysis of the part circular surface flaw problem by the alternating method. J. C. Newman [16] in 1973 derived an equation which related the linear elastic stress intensity factor, the applied stress, and two dimensional parameters; an empirical equation for the elastic magnification factors of the stress intensity factor for a surface crack in finite thickness plates was also developed. Buck, C. L. Ho and H. L. Marcus [17] described experimental results of crack propagation in part through crack specimens in which they found that changes in the loading spectrum causes time dependent relaxation and retardation effects which are not only reflected in the crack growth rate but also in the crack closure behavior. F. W. Smith and Sorensen [18] studied the mixed mode stress intensity factors for semi-elliptical surface cracks in 1974. At the end of 1975 Kobayashi, Polvanic, Emery and Love [19] studied surface flaws in plates under bending loads. Kathiresan [20] performed thesis research in the area of three dimensional linear elastic fracture mechanics analyses by a displacement hybrid finite element model in 1976. In the same year J. C. Newman [21] performed an analysis to predict failure of specimens with either surface cracks or corner cracks at holes. In 1977, Raju, and J. C. Newman [22] improved the stress intensity factor solution for semi-elliptical surface cracks in a finite thickness plate. They also developed a three dimensional finite element analysis of finite thickness fracture specimens. During 1979 [23] they continued to study the stress intensity factors for a wide range of semi-elliptical surface cracks in finite thickness plates. To verify the accuracy of the three dimensional finite element model employed, convergence was studied by varying the number of degrees of freedom. Stress intensity factors for shallow and deep semi-elliptical surface cracks in plates subject to tension loads were presented. They later developed an equation to express the stress intensity factors for surface cracks which was presented for finite thickness plates in tension and bending [24]. T. A. Cruse, A. E. Gemma, R. T. Lacroix and T. G. Meyer [25] presented in this year an overview of surface crack life prediction. R. M. Engle, Jr. [26] presented a survey of various analytical solutions currently used in part-through crack life prediction taking into account effects of flaw shapes. J. L. Rudd [27] presented predictions for surface flaw growth using compact tension specimen crack growth rate data. W. S. Johnson [28] developed a technique to predict constant amplitude crack growth of surface flaws. J. B. Chang [29] used a computer routine, EFFGRO, to calculate crack growth predictions of surface flaws. J. L. Rudd, T. M. Hsu and H. A. Wood [30], worked in the most common types of flaws in aircraft structure, taking into account residual stresses and initial flaw geometries. J. H. Underwood and J. F. Throop [31] presented a method for describing quantitatively the effect of residual stresses in cylinders with shallow flaws. Although much attention has been focused on this important problem, the recent results cited above indicate the need for further understanding of surface flaw behavior and improvement in predictive methodology. In Chapter 2 geometry, material properties, and stress field are taken into account to derive an equation which relates changes in crack depth, and crack length at the free surface. Surface crack growth behavior is studied in Chapter 3, where the particular geometry of growth is analyzed for shallow and deep cracks. The effect of material properties is also considered in this chapter. Material, test procedure, and data reduction techniques are described in Chapter 4. Chapter 5 presents the analyses of geometry configuration and life prediction and a comparison with the experimental results. Chapter 6 introduces an analysis of surface crack behavior under bending stresses."--Introduction.Item An interactive computer graphics package for the design of a robotic work cell(University of Missouri--Columbia, 1985) Suryanarayanan, Shankar; Sandgren, EricManufacturing systems are becoming increasingly complex and costly to implement. The simulation process must be utilized to test and analyze the many alternatives for robot cells as well as the overall factory. Currently the design of a Robotic Work Cell is mostly limited to either on-line procedures which cause costly interruptions in production or to the use of spare robots which requires additional investment in equipment. Using the techniques of Computer Aided Design a software package has been created to aid in the off-line design of a Robotic Work Cell. The use of this package will result in a verified robot path and shop floor layout prior to the decision to invest. The user can define objects of limited shapes and use them to define the workstation. The program checks for collision between the links of the robot and the objects in the workstation as the robot is in motion along the path generated by the user.