Residual Stress Measurement by ESPI Hole-Drilling

ESPI (Electronic Speckle Pattern Interferometry) is an optical method, used here to analyze the stress relief brought about by drilling a hole incrementally. Measurement times are substantially reduced compared to the standard hole-drilling method since no strain-gages have to be applied. Since repeat measurements can be made easily and quickly, measurement quality and stress distribution across the sample surface can be assessed well. This presentation focuses on practical measurement examples from different materials after shot-peening and under bending load. Factors affecting the measurement results are discussed.