Theses and Dissertations

Issuing Body

Mississippi State University

Advisor

Bhatia, Manav

Committee Member

Lacy, Thomas E.

Committee Member

Horstemeyer, Mark F.

Committee Member

Moser, Robert D.

Committee Member

Newman, James C. Jr.

Other Advisors or Committee Members

El Kadiri, Haitham; Priddy, Matthew W.

Date of Degree

5-3-2019

Document Type

Dissertation - Open Access

Major

Aerospace Engineering

Degree Name

Doctor of Philosophy

College

James Worth Bagley College of Engineering

Department

Department of Aerospace Engineering

Abstract

A physically motivated Internal State Variable (ISV) constitutive model is extended to account for shear influenced void evolution for predicting damage behavior in ductile solids. The revised ISV model is calibrated for an aluminum 7085-T711 alloy using a series of microstructure and mechanical property quantification experiments. The calibrated ISV model for the aluminum alloy is implemented in an implicit finite-element code (Abaqus) to simulate the deformation of notch Bridgman tension specimens at a variety of stress states and temperatures. The model revisions and calibrated aluminum ISV model are validated through successful prediction of mechanical and microstructure evolution for structures subjected to a variety of complex stress state conditions. The extended ISV model framework is used to study shear influenced plasticity and damage mechanisms resulting from ballistic impact of metals. A Rolled Homogeneous Armor (RHA) steel alloy is selected for the impact model due to wide availability of documented penetration characteristics and ballistic performance data of RHA steel. Finite Element Analysis (FEA) simulations of ballistic impact of rolled homogeneous armor (RHA) steel projectiles against RHA steel plates are performed using a calibrated ISV constitutive model for RHA steel. An FEA simulation based parametric study is performed to assess the effect of a variety of microstructure and mechanical properties on the ballistic performance of RHA steel targets. FEA simulations are used to predict a transition in ballistic perforation mechanisms for high hardness steel alloys by accounting for variations in microstructure properties qualitatively documented in the literature.

URI

https://hdl.handle.net/11668/20932

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