Doctor of Philosophy, The Ohio State University, 2016, Mechanical Engineering

Analytical solutions to fluid-structure interaction (FSI) problems provide a powerful design tool that has many applications within the automotive industry. The interaction of body panels with various fluid flows is of interest. Automotive panels that are made too thin become susceptible to a phenomenon known as oil-canning. The deformation can be temporary, or if the loading is large enough the panel can snap through, possibly resulting in permanent deformation. One common occurrence of oil-canning is when going through the dryer section of an automatic car wash. For small deformations the panel can shift between various unstable elastic configurations resulting in loud popping noises within the passenger compartment. Large deformations can result in permanent deformation and pitting of the roof panel. Automotive underbody panels are susceptible to water shock loadings that can be generated when driving over a puddle at high speeds. Panels that are made too thin can be permanently deformed or even fail in some cases when the water shock loading is strong enough. Accurate simulations of these scenarios are of interest since thinning body panels provides an easy way to realize significant weight reduction and increase fuel economy. An experimental program is introduced where full size automotive roof panels are subjected to air blast loading. The panels are stamped from thin alloy sheet steel. Roof panels are loaded into a custom test rig and clamped along the weld flanges. The air blast is generated using a commercial air compressor and a 35.1 mm pipe. Force imparted on the panel by the air jet is measured by three load cells and full-field displacement data is captured using three-dimensional digital image correlation (DIC). The flow field is characterized using piezo-resistive pressure transducers placed in a sensor bar apparatus that can be swept across the flow field to generate pressure maps. The pressure transducers are also mounted (open full item for complete abstract)

Committee: Amos Gilat (Advisor); Briam Harper (Committee Member); Chia-Hsiang Menq (Committee Member); Mo-How Shen (Committee Member) Subjects: Mechanical Engineering

Master of Science, The Ohio State University, 2010, Mechanical Engineering

Plastic deformation of 0.25” thick Ti-6Al-4V plate is investigated. Compression, tension and shear tests are carried out from quasi-static strain rates (10-4 s-1, 10-2 s-1) to high strain rates (up to 5x103 s-1) to study the strain rate sensitivity of the material. Tension and compression tests are carried out on specimens machined in different directions of the plate (at 0°, ±45°, 90° to the rolling direction of the plate in tension and at 0°, ±45°, 90° to the rolling direction and through the thickness of the plate for compression tests) to study the anisotropy effects. High temperature compression tests are carried out at 200° C, 400° C and 600° C to study the temperature effects on the plate. The setups required to perform all these tests and the theories behind the high strain rate tests are explained. The results show the strain rate sensitivity, anisotropy and the temperature effects on the Ti-6Al-4V plate. Johnson – Cook material constants are found out from the experimental data and simulations are run to fit the Johnson Cook model to simulate various tests.

Committee: Amos Gilat (Advisor); Brian Harper (Committee Member) Subjects: Mechanical Engineering; Mechanics