Degree Type

Dissertation

Date of Award

2013

Degree Name

Doctor of Philosophy

Department

Mechanical Engineering

First Advisor

Gap-Yong Kim

Abstract

Magnetostrictive Terfenol-D was examined as a prime-mover for bulk motion in a microforming system. Careful design and analysis led to the creation of a Terfenol-D transducer capable of 3.8 kN of blocked force and 212 µm of displacement. A linear model of the Terfenol-D transducer to simulate its output as a function of displacement under saturation magnetic field was created that matched both force and displacement within 10%. Thermal drift occurred at a rate of 2 µm/ºC. A flextensional lever system was designed to amplify the displacement of the Terfenol-D transducer to levels sufficient for microforming. Sub-micron displacement resolution was observed, with no perceivable effects from friction or backlash. The full system provided 365 N of blocked force and 1.6 mm of displacement. A linear model of the full system was also created that used the linear model of the transducer's output which matched experimental results for displacement with a 2% error and force with an 11% error, which was found to be useful for selection of design parameters.

In ultrasonic-assisted punching, a circular punch of 3.2 mm diameter that vibrates transversely at 9.6 kHz was used to punch samples of 1100-O at several punching speeds and vibration intensities. Higher speed punching tests showed up to a 30% reduction in punching force accompanied by an apparent elimination of adiabatic strain rate effects. Lower speed punching showed a smaller degree of softening, but an increased burnished-to-fractured area ratio.

A study on the effects of vibration waveform on a polymer vibration welding process on 0.25 and 0.5 mm ABS sheet was conducted using sine, square, and triangle waves at differing penetration depths. A preliminary study was first used to determine control levels of basic welding parameters that compared the effects of clamping load and penetration depth on the two sheet thicknesses. It was found that square waves provided slightly higher penetration rates than sine waves, and triangle waves significantly lower penetration rates than sine waves. Penetration rates and achievable penetration depths varied with sheet thickness. A minimum penetration rate threshold was found below which it was not possible to achieve adequate penetration; beyond this lower penetration rates generally resulted in higher strength.

DOI

https://doi.org/10.31274/etd-180810-3579

Copyright Owner

Adam Timothy Witthauer

Language

en

File Format

application/pdf

File Size

110 pages

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