Engineering Commons^™

Molten Aluminum Capillary Hole-Filling, Cheng-Nien Yu

Theses and Dissertations--Mechanical Engineering

The presence of micrometeoroids and space debris in open space raises the question of a mitigation of the damage caused by a possible impact on the man-made structures such as space shuttles, satellites, and the International Space Station. A method achieving metallic sealed hole would be of an interest for development. This dissertation studies a surface tension driven capillary filling/sealing phenomenon in a controlled atmosphere brazing process of aluminum. The filled vs. non-filled results are predictable using minimization of energy, which shows that the outcomes depend heavily on prescribed configurations of the hole. Equilibrium models show excellent agreement with experimental …

The Influence Of Cryogenic Machining On Surface Integrity And Functional Performance Of Titanium Alloys For Biomedical And Aerospace Applications, Ying Sun

Theses and Dissertations--Mechanical Engineering

The excellent properties of titanium alloys such as high strength, as well as good corrosion and fatigue resistance are desirable for the biomedical and aerospace industry. However, the same properties that make titanium alloys desirable in high-performance applications also make these space-age materials “difficult-to-machine” materials, as the titanium alloys exhibit high cutting temperatures because of their high strength and low thermal conductivity.

Cryogenic machining is a severe plastic deformation (SPD) processes which uses liquid nitrogen as the coolant to take away the heat generated during machining in a relatively short time. Cryogenic machining can significantly reduce the cutting temperatures at …

Stress Generation In Ni50.3Ti29.7Hf20 Shape Memory Alloys, Utsav Shah

Theses and Dissertations--Mechanical Engineering

Shape memory alloys such as NiTiHf and NiTi have the ability to generate large recovery stresses when they are constrained after pre-straining and then heated above their Austenite Finish Temperature (A_f). In this work Ni_49.9Ti_50.1 (at.%), the most well-known SMA with impressive shape memory properties but limited temperature range and Ni_50.3Ti_29.7Hf₂₀, a promising high temperature shape memory alloy, were characterized to reveal their stress generation capabilities. The effects of pre-straining on stress generation were investigated via martensite reorientation method of NiTi and NiTiHf alloys by loading the samples till …

Influence Of Size Effects On Surface Generation During Finish Machining And Surface Integrity In Ti-6al-4v, Ian S. Brown

Theses and Dissertations--Mechanical Engineering

Finish machining is an essential manufacturing process that is used to enhance the mechanical characteristics of critical components. The deformation that occurs at the tool and workpiece interface in finish machining significantly affects a host of component properties, commonly referred to as “surface integrity” properties. Surface roughness is a machining deformation-affected characteristic that is of high relevance in contemporary manufacturing. However, over recent decades it has been made clear that the material properties of the deformed surface layers are relevant to component performance as well. Predicting the overall surface quality of a machined component is of great relevance to the …

Numerical Analyses And Integration Of Split Lot Sizing Using Lean Benchmark Model For Small Lot Manufacturing In High Mix Low Volume Production, Omkar Bhosale

Theses and Dissertations--Manufacturing Systems Engineering

As the global demand for automobiles has increased rapidly over the last fifty years, customers have become more particular about the characteristics of the autos they want. This change in demand, in part has pushed manufacturing to become more flexible and created a demand for alternative, more efficient processes like the High Mix Low Volume (HMLV) production of vehicles. During HMLV, manufacturers create production lot sizes and schedule to synchronize the production processes to meet customer demand on time. The demand for the automobile parts may not be uniform or parts may not be consumed by the customer immediately, Due …