Residual stress measurement on the butt-welded area by electronic speckle pattern interferometry

Abstract

a b s t r a c tBackground: Residual stress always exists on any kind of welded area. This residual stress

Optimization of Resistance Spot Welding (RSW) Parameters by using Taguchi Method

“…If the welding power is so high, the welding transformers can be damaged and the welding circuit switched off [5]. According to Kim et al [6], the residual stresses remaining in the welded component will also increase if the welding current and the tensile load are increased.…”

Subwavelength Resonant Gratings for Micrometric Strain Sensors

“…The search of other technologies using optical phenomena is currently a hot research topic, some of them are even commercially available. For instance, photoelasticity [3] in which watery colored lines denote lines of constant strain, the number of fringes determine the strain, the sensitivity depend on the coating material, from 1% to 4% (PhotoStress® Instruments, Tech Note TN-704-2); Moiré interferometry [4], combining with hole drilling methods is possible to reduce the effect of vibrations, still the interrogation system is rather complicated and hole drilling is a destructive method; Holography [5] based on digital recording and reconstructing the wavefronts from two exposures, is capable of reproduce very accurately 2D strain maps but the sensitivity is not reported; Speckle interferometry [6] offers an improved speed of evaluation and is a not destructive method. A heterodyning [7] has been investigated for measuring the in-plane displacement of a rough object, a displacement up to 220 μm and displacement variation down to the nanometer range is demonstrated, also a sensitivity of 0.8°/nm.…”