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
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.
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