Residual Stress Measurement Using Incremental Hole-Drilling and Digital Image Correlation with Scheimpflug Optics

The present study investigates residual stress measurement using the incremental hole-drilling method combined with optical deformation measurement by digital image correlation. Experiments were performed on a steel specimen with a non-uniform stress distribution introduced by four-point bending, enabling direct comparison between the applied stresses and the evaluated stresses. A key feature of the experimental setup was the use of a Scheimpflug lens, which allowed the drilling unit to remain in place throughout the test. This eliminated the need to alternate between the drilling device and the imaging system and, consequently, removed the requirement for highly precise repositioning. In addition, the optical system mounting was designed to capture the drilled hole from multiple viewing directions. This approach provided several essentially independent measurements of deformation around the hole within a single drilling experiment, thereby increasing the robustness and reliability of the stress evaluation.