Residual stress measurement combining blind-hole drilling and digital image correlation approach

Abstract

In this study, digital image correlation (DIC) combined with the hole-drilling method is used to measure residual stress in full-scale steel components. According to the displacements before and after drilling, the theoretical expressions of residual stress are derived. The finite element (FE) method is used to solve for the estimated coefficients, which provides the basis for the experiment. An H-shaped steel beam specimen is used in the benchmark experiment to verify the feasibility and reliability of the DIC-hole drilling method. Combining DIC with hole-drilling technology, the speckle image information and displacement fields of the specimen before and after hole-drilling are extracted. The residual stress is then calculated and compared with the results of theoretical calculations, and the causes of the differences are analysed. In order to strengthened the validation of the method, hole-drilling method is used here to make comparisons with DIC-hole drilling method. The results indicate that the DIC-hole drilling is a feasible and sufficiently accurate method for measuring the residual stress in full-scale steel components. The displacement field in the regions centred at a distance of 2–2.5 times the radius from the hole is proposed for the accurate measurement of the residual stress. The accuracy of the DIC-hole drilling method is sufficient for the measurement of high values of residual stress. When the measured residual stress σx > 100 MPa, the difference is about 10%.