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Advisor(s)
Abstract(s)
The goal of this work is the development of different experimental techniques to measure residual stresses, as alternative to the hole-drilling method with strain gages. The proposed experimental techniques are based on the use of Moiré Interferometry and in-plane Electronic Speckle Pattern Interferometry (ESPI). Both are field techniques allowing the assessment of in-plane displacements without contact and high resolution. Grating replication techniques were developed to record high quality diffraction gratings onto the specimen’s surfaces. An optical set-up of laser interferometry was, developed to generate the master grating (virtual). An in-plane ESPI set-up was also designed and implemented to measure displacements in one direction. The stress relaxation was promoted by the blind hole drilling and the obtained fringe patterns (Moiré and speckle) were video recorded. Image processing techniques were applied to assess the in-plane strain field. A finite elements code (ANSYS®) was used to simulate the stresses relaxation process whose values were compared with the experimental data and to calculate the hole-drilling calibration constants.
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Citation
Ribeiro, J.E.; Monteiro, J.; Vaz, M.A.P.; Lopes, H.; Piloto (2006). Residual stress assessment using optical techniques. In 5th International Conference on Mechanics and Materials in Design. Porto. ISBN 972-8826-11-7