Mechanical Engineering Commons^™

Experimental Analysis Of Protective Headgear Used In Defensive Softball Play, John Scott Strickland

UNF Graduate Theses and Dissertations

Every year in the United States, an estimated 1.6 to 3.8 million people sustain sports-related traumatic brain injuries (TBIs), with an appreciable number of these injuries coming from the sport of softball. Several studies have analyzed the impact performance of catcher’s masks within the context of baseball; however, virtually no studies have been performed on fielder’s masks within the context of softball. Thus, the main objective of the present work was to evaluate the protective capabilities of softball fielder’s masks. To better understand the injury mechanisms and frequency associated with softball head/facial injuries, epidemiological data from a national database was …

A Process, Structure, And Property Study Of Gallium-Based Room Temperature Metallic Alloys, Courtney Lyn Titus

UNF Graduate Theses and Dissertations

Amalgamations are a promising replacement for electronic solders, thermal interface materials, and other conductive joining materials. Amalgams are mechanically alloyed materials of a liquid constituent with a solid powder. Unlike traditional solders, these materials are processed at room temperature or slightly above, and can often operate at temperatures near, or beyond, their processing temperatures. Existing bonding processes require an excessive amount of heat, which may cause thermal stress to the electronic components and delaminate the attachment. Amalgams have promising characteristics for thermal interface materials (TIMs) due to being fully metallic, relatively easy of handling, and possessing metallic strength similar to …

Landing-Gear Impact Response: A Non-Linear Finite Element Approach, Tuan H. Tran

UNF Graduate Theses and Dissertations

The primary objective of this research is to formulate a methodology of assessing the maximum impact loading condition that will incur onto an aircraft’s landing gear system via Finite Element Analysis (FEA) and appropriately determining its corresponding structural and impact responses to minimize potential design failures during hard landing (abnormal impact) and shock absorption testing. Both static and dynamic loading condition were closely analyzed, compared, and derived through the Federal Aviation Administration’s (FAA) airworthiness regulations and empirical testing data.

In this research, a nonlinear transient dynamic analysis is developed and established via NASTRAN advanced nonlinear finite element model (FEM) to …

Reduction Of Nox Emissions In A Single Cylinder Diesel Engine Using Sncr With In-Cylinder Injection Of Aqueous Urea, Anthony Timpanaro

UNF Graduate Theses and Dissertations

The subject of this study is the effect of in-cylinder selective non-catalytic reduction (SNCR) of NO_x emissions in diesel exhaust gas by means of direct injection of aqueous urea ((NH₂)₂CO) into the combustion chamber. A single cylinder diesel test engine was modified to accept an electronically controlled secondary common rail injection system to deliver the aqueous urea directly into the cylinder during engine operation.

Direct in-cylinder injection was chosen in order to ensure precise delivery of the reducing agent without the risk of any premature reactions taking place. Unlike direct in-cylinder injection of neat water, …