Date of Award

12-2012

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Legacy Department

Automotive Engineering

Advisor

Mears, Michael L

Committee Member

Grujicic , Mica

Committee Member

Collins , Randy

Committee Member

Abu-Farha , Fadi

Abstract

This work studies the influence of an applied electrical current on magnesium sheet metal and introduces models which are successful in predicting the deformation behavior (i.e. material flow stress, local material strain, and thermal response). Also, this work examined the theory of electroplasticity by studying prior proposed theories and by quantifying the prior theories potential for improved dislocation mobility. From this analysis, a single dominant mechanism is determined and the theory of electroplasticity is explained using this single mechanism. The theory discussed in this work is supported by experimental testing and microstructure analysis.
In addition to studying the exact electroplastic mechanism, the electrical energy added to the system results in a decrease in the material flow stress. The decrease in flow stress is due to the direct electrical effect (i.e. electroplasticity), bulk thermal softening from the temperature rise, and thermal expansion effects. Each of these effects are predicted by models and quantified in this work.
Aside from the theory and modeling aspects of this work, the applicability of Electrically-Assisted Forming (EAF) to unique processing techniques is performed. Specifically, control strategies of constant force forming, constant stress forming, and constant current density forming were envisioned and demonstrated. Thus, new class of control approaches is developed for EAF. Also, the applicability of the introduced EAF models are analyzed for use in model predictive control strategies.

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