Theses and Dissertations

Ali Najafi

Issuing Body

Mississippi State University

Advisor

Rais-Rohani, Masoud

Committee Member

Bammann, Douglas

Committee Member

Horstemeyer, Mark

Committee Member

Marin, Esteban

Committee Member

Haupt, Tomasz

Other Advisors or Committee Members

Oppenheimer, Seth

Date of Degree

8-6-2011

Document Type

Dissertation - Open Access

Major

Computational Engineering (Program)

Degree Name

Doctor of Philosophy

College

James Worth Bagley College of Engineering

Department

Department of Aerospace Engineering

Abstract

Coupling of material, process, and performance models is an important step towards a fully integrated material-process-performance design of structural components. In this research, alternative approaches for introducing the effects of manufacturing and material microstructure in plasticity constitutive models are studied, and a cyberinfrastructure framework is developed for coupled process-performance simulation and optimization of energy absorbing components made of magnesium alloys. The resulting mixed boundary/initial value problem is solved using nonlinear finite element analysis whereas the optimization problem is decomposed into a hierarchical multilevel system and solved using the analytical target cascading methodology. The developed framework is demonstrated on process-performance optimization of a sheetormed, energy-absorbing component using both classical and microstructure-based plasticity models. Sheetorming responses such as springback, thinning, and rupture are modeled and used as manufacturing process attributes whereas weight, mean crush force, and maximum crush force are used as performance attributes. The simulation and optimization results show that the manufacturing effects can have a considerable impact on design of energy absorbing components as well as the optimum values of process and product design variables.

URI

https://hdl.handle.net/11668/20265

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