Assessing the Accuracy of Residual Stress Measurement Results on a 2024-T351 Aluminum Alloy Ring-And-Plug Specimen using X-Ray Diffraction and Incremental Hole Drilling Methods

Abstract Background Establishing the accuracy of residual stress measurements in aluminum alloys, such as 2024-T351, remains a topic of significant interest in the aerospace structures community. Achieving this requires a comprehensive understanding of the potential sources of error associated with each residual stress measurement methodology. Objective The primary objective of this study is to identify and characterize potential sources of experimental error in residual stress measurements performed on a 2024-T351 aluminum alloy ring-and-plug specimen. Methods A ring-and-plug specimen was manufactured for its predictable stress state. A series of x-ray diffraction (XRD) and incremental hole drilling (HD) measurements were then performed. Multiple sources of potential error were investigated, including sample geometry, crystallographic texture, and grain size. Results A high variability in HD and XRD point-to-point measurements was observed, attributed to the large grain size. This variability drives the need for a robust sampling strategy that minimizes uncertainty. Conclusions The comparison of XRD and HD measurements on the 2024-T351 ring-and-plug specimen revealed distinct error sources inherent to each technique. Therefore, multiple measurements and potentially a combination of different measurement techniques are required on material systems with grain sizes that are large relative to the measurement techniques representative volume element (RVE) to ensure accurate residual stress results.