Noise Sensitivity of Optical Techniques using the Hole Drilling Approach for Residual Stress Measurement

The hole drilling technique is a well known experimental method for residual stress investigation. This technique is usually used in combination with electrical strain gages but this choice may not prove the best one as alternative approaches are possible. In particular, some optical measurement techniques (grating interferometry, speckle interferometry, holographic interferometry, shearography) can be advantageously used. Since all these optical techniques provide full field information, it becomes important to make proper use of these data to increase the robustness and reliability of the analysis. In this work, various well known approaches to this problem have been investigated, first by performing a sensitivity analysis, then by using a simulated (known) displacement field and analyzing the performance of the various techniques in the presence of noise.