Search Results for optical-metrology

Abstract

Accurate measurement of residual stress is crucial for assessing structural integrity and predicting fatigue life. Although significant work has been documented on applying two-dimensional (2D) and three-dimensional (3D) digital image correlation (DIC) independently to the hole drilling process, a direct comparison of their accuracy and performance under the same conditions (most importantly, with plastic deformation) has not yet been published. This work conducted the first explicit comparison between 2D and 3D-DIC combined with the hole drilling method for residual stress measurement using finite element (FE) analysis as a validation standard. Residual stresses were induced through plastic bending of a square beam made of aluminum alloy 7075-T651. The findings indicate that the 3D-DIC is more accurate (93%) compared to the 2D-DIC (88%), objectively tested against FE solutions, even on a flat surface, which is theoretically ideal for 2D-DIC.This difference in accuracy is attributed to the higher sensitivity of the 2D-DIC to out-of-plane deformation and camera misalignment. These results support the effectiveness of 3D-DIC in measuring residual stress and explain that there is a trade-off between the practical accuracy of 2D and 3D versions of the hole-drilling technique.