Remarks on Residual Stress Measurement by Hole-Drilling and Electronic Speckle Pattern Interferometry

Table 1

Values of the measured average stress obtained by keeping constant 𝑅_int = 1.59 mm and by changing 𝑅_ext. The expected theoretical value was 𝜎_𝑥𝑥 = 138 MPa. Also standard deviations are reported as a result of three different drilled holes.

	𝑅ext = 2.07 mm	𝑅ext = 2.23 mm	𝑅ext = 2.38 mm	𝑅ext = 2.62 mm
𝜎𝑥𝑥 [MPa]	135.3	136.7	137.3	137.3
Δ𝜎𝑥𝑥 (%)	1.9	0.9	0.5	0.4