Date of Award

Fall 2016

Project Type

Thesis

Program or Major

Mechanical Engineering

Degree Name

Master of Science

First Advisor

Brad L Kinsey

Second Advisor

Yannis P Korkolis

Third Advisor

Marko Knezevic

Abstract

An experimental technique called Continuous-Bending-under-Tension (CBT) can produce elongations over two times that of a standard tensile test by preventing the necking instability from occurring. This is achieved by superposing plastic bending on tension along the gauge length of the material using three rollers. The specimen is kept under tension as the rollers apply three-point bending while cyclically traversing the gauge length. This subjects the specimen to plastic deformation only in the region that is visited by the rollers. Details on the design of various subsystems of this unique CBT machine are presented. The results for a variety of CBT experiments in the rolling direct (RD) and transverse direction (TD) were conducted to explore the CBT parameter space. Two additional types of experiments were conducted using the CBT machine. In one, interrupted CBT experiments were conducted to study the development of the grain structure within the gauge region during the CBT process. In the other, friction tests were used to determine the coefficient of friction between AA6022-T4 and the steel rollers during the CBT process. The latter is proposed as a general method to measure the friction coefficient between a sheet and a die. The manufacturing industry will benefit from a stronger fundamental understanding of the mechanisms that improve the potential elongation for the CBT process.

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