Residual Stress Measurement Using Hole Drilling and Integrated Digital Image Correlation Techniques

The effectiveness of optical (mostly interferometric) methods for the measurement of residual stresses is largely demonstrated in literature. Nevertheless, these techniques are still confined to optical laboratories due to their high sensitivity to vibrations which makes it very difficult to perform the measurement in an industrial environment. Digital Image Correlation (DIC) has recently been proposed as a possible solution to this problem: this non-interferometric technique is much less affected by vibrations, but its sensitivity is relatively low, thus negatively affecting the accuracy of results. This work proposes to use a variant of Digital Image Correlation, known as Integrated DIC (iDIC), in combination with the hole drilling technique. Since iDIC directly incorporates in its formulation the displacement field related to hole drilling, it overcomes most of the problems of standard DIC; in this way it is possible to obtain accurate results without using interferometric techniques.