Engineering Commons^™

Global Skin Friction Diagnostics In Complex Separated Flows, Sudesh A. Woodiga

Masters Theses

This work describes the application of a global luminescent oil film skin friction meter to quantitative global skin friction diagnostics in complex separated flows. The development of this technique is based on the relationship between the oil film thickness and luminescent intensity of an oil film mixed with a luminescent dye. The projected thin oil film equation is given to relate the normalized luminescent intensity with skin friction. The basis for this technique is the variational solution for the thin oil film equation on the image plane. The variational formulation with a smoothness constraint on skin friction is proposed to …

Generation And Analysis Of Fcg Data Using A Single Specimen And Kmax - ∆K Testing Matrix, Sree Phani Chandar Reddy

Masters Theses

A custom method to generate fatigue crack growth (FCG) data requires testing of multiple specimens at different load ratios. In addition, it includes the application of a load shedding procedure from pre-cracking level to threshold.

In this thesis, a novel method of testing has been investigated that utilizes a single specimen and a testing matrix in terms of K_maxand ∆K values corresponding to predetermined R-ratios for which FCG data, da/dN, are recorded. Automatic K-controlled tests on 2324-T39 Al alloy were conducted using the ∆K increasing and ∆K decreasing procedures while K_maxwas kept constant. Results show that …

Ductile-Regime Machining Of Silicon Carbide And Quartz, Deepak Ravindra

Masters Theses

Silicon carbide (SiC) and quartz are one of the advanced engineered ceramic materials designed to operate in extreme environments. One of the main reasons for the choice of these materials is due to its excellent electrical, mechanical and optical properties that benefit the semiconductor, MEMS and optoelectronic industry respectively. Manufacturing these materials is extremely challenging due to its high hardness, brittle characteristics and poor machinability. Severe fracture can result when trying to machine SiC and quartz due to its low fracture toughness. However, from past and current research efforts, it has been proven that ductile regime machining of brittle materials …

Prediction Of Fatigue Crack Growth Retardation Due To A Tensile Overload Using Two-Parameter (∆K, Kmax) Approach, Wataru Tsutsui

Masters Theses

A theoretical crack growth study on powder metallurgy aluminum alloys AA5091 and AA8022 was conducted. Specifically, the research focused on the crack growth retardation due to the application of a tensile overload. The tensile overload creates a plastic zone ahead of the propagating crack tip that induces the compressive residual stress after unloading. Such compressive residual stress pushes the crack tip faces against each other, which results in crack growth retardation.

In the study, simulation started from the calculation of the compressive residual stress. The details of the calculation steps are explained in the thesis. Eventually, the stress intensity factor …

Investigative Study On An Energy Theorem For Developing Testing Functions For Numerical Simulations Of Multibody Dynamic Systems, Kulasegaram Gugaratshan

Masters Theses

Multibody dynamic systems designers utilize computer software extensively to simulate the motion of mechanical systems. The governing differential equations of motion are formulated and solved numerically. The accuracy of the numerical solutions is always a concern to the analyst. There have been many investigations done around the world to check the accuracy of these simulations, and based on these investigations, many methods have been developed. These methods are usually based on energy balance equations and can be used to test the validity or the correctness of the numerical solutions. This thesis analyzes and compares these methods based on their formulation …

Iterative Design Of The Aeroship Through Flight Testing, Michael R. Schulte

Masters Theses

This research covers the design, construction, and testing of a hybrid flight platform called the Aeroship. The Aeroship is a combination of current aerodyne and aerostat technology that have been merged at an optimal ratio. In order to create an efficient design, flight testing was employed as a catalyst for design changes. The final design was then flight tested for performance validation using videogrammetry.

Improving Query Efficiency Of Multiresolution Data Aggregation For Analytical Exploration Of Large Relational Dataset, Yu-Ting Huang

Masters Theses

Tree structures are developed to organize the data more efficiently by using fewer resources for searching records. This thesis investigates the tree's actual structure on the hard disk to see the influence of different kinds of structures on the tree building time and query execution time. In order to improve efficiency, one multi-file structure and two reorganization structures, BFS and DFS, are examined to achieve this goal. The results indicate that two reorganization structures on KDB-tree structure can significantly improve the query execution time in large data sets and multi-file structure can slightly improve the TPIE lover level building time.

Incorporation Of Space Syntax Theory In Determining Safe And Efficient Construction Site Layout, Minsuck Cho

Masters Theses

Facility layout is an important to determine a proper arrangement of temporary facilities in a construction site. It significantly impacts productivity and safety of construction. The objectives of layout planning are to minimize travel distance and time, to decrease the facility transportation and setup costs, and to improve site safety. Despite the importance of facility layout, it is often overlooked in the planning phase. Several models have been developed taking some of these factors into consideration; however, construction managers and site planners often regard cost as the most important factor in layout planning and pay less attention to safety and …