Title page for ETD etd-041210-195754

Document Type dissertation

Author Name Spence, Timothy

URN etd-041210-195754

Title The Effect of Machining Residual Stresses on the Dimensional Stability of Aluminum Alloys used in Optical Systems

Degree PhD

Department Materials Science & Engineering

Advisors
Dr. Makhlouf M. Makhlouf, Advisor
Dr. Richard Sisson, Jr., Department Head
Dr. Jianyu Liang, Committee Member
Dr. Diran Apelian, Committee Member
Dr. John Dion, Committee Member

Keywords
Dimensional Stability
Residual Stress

Date of Presentation/Defense 2010-04-14

Availability unrestricted

Abstract
Dimensional stability of materials is of critical importance in the fabrication of precision components used for applications such as optical systems. One source of dimensional instability is residual stress produced on the surfaces of parts due to machining operations. A creep model is proposed in this research that describes how these stressed layers affect the overall geometry of a component as they creep over time and temperature. Depth corrected XRD stress measurements and a bimetallic strip model were utilized to quantify the residual stress layer of two machining operations. The creep model parameters were determined by monitoring curvature over time and temperature. This model can be used for two purposes, the prediction of long term storage effects on part geometry for purposes of reliability assessment, and the design of short term, moderate temperature stress relief treatments. Two alloys were investigated, aluminum 6061-T6, and aluminum 4032-0. A methodology for applying the observed creep strain to complex parts using a finite element analysis is proposed.

Files
SpenceT.pdf

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Document Type	dissertation
Author Name	Spence, Timothy
URN	etd-041210-195754
Title	The Effect of Machining Residual Stresses on the Dimensional Stability of Aluminum Alloys used in Optical Systems
Degree	PhD
Department	Materials Science & Engineering
Advisors	Dr. Makhlouf M. Makhlouf, Advisor Dr. Richard Sisson, Jr., Department Head Dr. Jianyu Liang, Committee Member Dr. Diran Apelian, Committee Member Dr. John Dion, Committee Member
Keywords	Dimensional Stability Residual Stress
Date of Presentation/Defense	2010-04-14
Availability	unrestricted
Abstract Dimensional stability of materials is of critical importance in the fabrication of precision components used for applications such as optical systems. One source of dimensional instability is residual stress produced on the surfaces of parts due to machining operations. A creep model is proposed in this research that describes how these stressed layers affect the overall geometry of a component as they creep over time and temperature. Depth corrected XRD stress measurements and a bimetallic strip model were utilized to quantify the residual stress layer of two machining operations. The creep model parameters were determined by monitoring curvature over time and temperature. This model can be used for two purposes, the prediction of long term storage effects on part geometry for purposes of reliability assessment, and the design of short term, moderate temperature stress relief treatments. Two alloys were investigated, aluminum 6061-T6, and aluminum 4032-0. A methodology for applying the observed creep strain to complex parts using a finite element analysis is proposed.
Files	SpenceT.pdf