Mechanical Engineering Commons^™

Finite Element Analysis Of The Femoral Head, Ghandikota Ramamurthy

Theses

Femoral component loosening and Prosthetic stem fractures have renewed interest in conservative alternatives to conventional total hip replacements. One such alternative is the concept of surface replacement. The objective in this study is a finite element analysis of a femoral surface replacement cup with Particular attention given to the interfacial stresses. An axisymmetric model with a grid of two-dimensional isoparametric elements is generated. This study utilizes an adaptive model so as to include the effect of bone remodeling in response to stress. The stiffness is considered to be linearly proportional to the stress in the femoral head and neck. Isotropic …

One-Dimensional Compressible Flow Analysis : Isentropic And Normal Shock, Su-Bo Wong

Theses

A computer program to compute and analyse one-dimensional isentropic compressible flow through variable cross-sectional area with or without a normal shock is developed. The program is written in the "FORTRAN LANGUAGE".

In this work, the area change is the predominant cause of change of flow condition. One of the advantage of this program is set on general uses for isentropic flow. In common practice, the values of the isentropic flow property ratios were tabulated or graphically presented as function of the Mach number with a specified specific heat ratio, K (normally K=1.40 was presented). With todays technology, the most versatile …

Computer Simulation Of Cavity Filling During Injection Molding Process, Sumit Banerjee

Theses

A numerical technique is proposed for the simulation of cavity filling process during injection molding of glass-bead filled polypropylene. The mold cavity is of cylindrical shape. Marker And Cell (MAC) method is utilized for solving the transient flow phenomena, after a mathematical simulation of the flow model is carried out by using the relevant continuity and-momentum equations governing the system. The complexity of the equations involved, results in the simplifying assumption of incompressible and isothermal flow process. A computer program is written on the basis of finite-difference equations developed during the application of MAC method under the prevailing conditions.

The …

On The Space Shuttle Wing Thermal-Structural Analysis, Kumar Krishna Tamma

Mechanical & Aerospace Engineering Theses & Dissertations

A finite element approach for efficient thermal-structural analysis of structures with thermal protection systems (TPS) is described. The approach is applied to Space Shuttle wing structure configurations subjected to reentry heating. New two and three-dimensional finite elements are developed to model heat transfer in the TPS and supporting structure. A typical TPS/Structural element predicts transient nonlinear temperature variations through the TPS thickness and detailed structural temperatures at the TPS/Structure interface. The accuracy of the TPS/Structure approach in two and three-dimensions is evaluated by comparisons with the conventional approach for various configurations of the wing structure. The results indicate that the …

Liquid Transmission Line Pulser Circuit For Laser Excitation, Carl Stultz

Dissertations and Theses

The subject of this thesis is the study of liquid dielectric transmission lines and their potential application as an excitation source in high speed, high-repetition rate laser designs. The design problems associated with the construction of high repetition rate (khz), short wavelength lasers have been reviewed and the major shortcomings of conventional electrical driving circuits identified. The identification of these shortcomings and a review of the available literature on electrical circuits for various types of lasers suggested that liquid dielectrics and transmission lines could potentially have significant advantages over more conventional circuitry used in high repetition rate, short wavelength lasers. …

Investigation Of Important Surface Characteristics Of A Finned Tube Heat Exchanger, Bobby Dale Stafford

Masters Theses

"Surface characteristics of a finned tube heat exchanger were examined to help predict the contact geometry between metal surfaces. These characteristics were the surface roughness and waviness and the material hardness. A scanning electron microscope was used to observe the surface topography of the fins as well as examining the contact between the aluminum fin and the copper tube.

Comparisons of the surface roughness were then made between heat exchangers having different fin numbers (20, 14, and 6) with the result that as the fin number decreased, the roughness also decreased. For a given fin number, it was discovered that …

A Technique For Obtaining Very Efficient Dynamical Equations For On-Line Computation Of Joint Forces Of Robotic Mechanisms, Dennis A. Dohogne

Masters Theses

"In order to increase the operational speed and positional accuracy of robotic mechanisms, on-line force control has been proposed. Because of the complexity of exact dynamical formulations, real-time computation of joint forces may be too slow.

Since force control is accomplished with a dedicated computer, unique, dedicated sets of force equations are justified. An efficient force computation technique based on the algebraic expansion and recombination of exact dynamics formulations is presented. Developments of the robotics matrix notation and of a Lagrangian dynamics formulation are also presented. A generalized three link manipulator model is used to compare the computational complexities of …

Stability Analysis Of Closed Surge Tanks By Phase-Plane Method, Mostafa A. Sabbah

Civil & Environmental Engineering Theses & Dissertations

The governing equations describing water level oscillations in a closed surge tank with compressed air at the top of the tank are a set of nonlinear ordinary differential equations if the hydraulic system is analyzed as a lumped system. These oscillations are stable or unstable depending on the parameters of the plant and the type and magnitude of the disturbance.

The present available stability criterion has been developed by linearizing the governing equations and is, therefore, valid only for small disturbances.

In the research reported herein, the governing equations are normalized to reduce the number of parameters from nine to …

Relationships Between Selected Features Of Helical Or Spur Gears And Size Distortions Due To Heat Treatment, Abolghassem Tolu Honary

Dissertations and Theses @ UNI

The purpose of this study was to determine the relationships between selected gear features and distortions due to heat treatment. An extensive review of the literature indicated that studies on gear distortions were mainly metallurgically oriented, and the relationships between gear geometrical features and dimensional distortions due to heat treatment had not been investigated.

This investigation obtained data from actual gear size adjustments that had been collected from many years of experimentations at the John Deere Component Works (JDCW), Waterloo, Iowa. Gear data were converted to uniform files and were classified, retrieved, and analyzed by computerized systems. Two groups of …