Masters Theses

Date of Award

12-2025

Degree Type

Thesis

Degree Name

Master of Science

Major

Civil Engineering

Major Professor

Dr. Dayakar Penumadu

Committee Members

Dr. Jeffrey Bunn, Dr. Mark Denavit

Abstract

Residual stresses within alloys can result from a multitude of complex processes associated with additive and subtractive manufacturing, extrusion, casting, machining, and welding due to thermo-mechanical loading. Residual stress within a structural element can lead to early yielding and premature failure of the part. Cyclical and long-term use of structural elements can lead to the development of residual stress. The importance and presence of residual stress extend into structural, aerospace, materials engineering, and other sectors where the resulting failure is catastrophic. The ability to accurately measure residual stresses within a structural component is essential to the lifetime of the part. Many methods currently exist for measuring residual stress, including diffraction-based techniques, compliance, curvature, and blind hole drilling.

Blind hole drilling is an advantageous measurement technique because it is semi-destructive and can be implemented in an engineering setting. Blind hole drilling is conventionally completed with typical strain gauge rosettes, as outlined in ASTM E837. A major drawback of standard strain gauge rosettes is the lack of measurement area available. Strain gauge rosettes also require precise and time-consuming preparation, require precise orientation on the part, and are single use. The application of 3D DIC (three-dimensional digital image correlation) to the blind hole drilling method provides a larger measurement area and simplifies sample preparation. In this study, 3D DIC is applied to the blind hole drilling method of measuring residual stress. The traditional method of residual stress calculation for incremental hole drilling, the integral method, is applied to 3D DIC. The 3D DIC integral method results are compared to a newly proposed method which uses radial displacements and calibration coefficients derived from finite element models to increase the accuracy of residual stress measurement.

Mesoscopic (Type II) and microscopic (Type I) residual stresses are typically of academic interest, while Type I bulk residual stresses are of highest importance for engineering applications. Type I residual stresses are addressed in this study by improving on the ASTM hole drilling procedure with the application of 3D DIC. The integrated 3D DIC application to the incremental hole drilling procedure is verified by traditional strain gauge rosette measurements and with known applied stress in 4-point bending. A full residual stress analysis of a shrink fit ring and plug sample is evaluated in this study with measurement by hole drilling with standard strain gauge rosette and 3D DIC, x-ray diffraction, neutron diffraction, and preliminary Bragg edge imaging results.

Download
Files over 3MB may be slow to open. For best results, right-click and select "save as..."

Share

COinS