Residual-Stress Analysis by Local Laser Heating and Speckle-Correlation Interferometry

Wedge prism for direction resolved speckle correlation interferometry

“…Further details on the mechanical test frame, the temperature sensitive paint, and the interferometer set up are available elsewhere. 6,8 Since the room temperature was 22.4 °C, the particular paint allows 570.6 °C temperature increase in the ramp heating cycle(5 s maximum 60 W at 2.5 s ). However, the laser spot size was larger than 2 mm diameter paint spot, so the entire laser power of 60 W was not actually used.…”

“…In fact, in the stress measurement problems, we have found that fringe counting along a line yields enough quantitative data. 6,8,10 In this paper, we present the design aspects of such a prism with some experimental results. Besides the current need of the sign determination, the approach should also be useful in spatial phase shifting interferometry.…”

“…Thus, if possible, precisely known phase of the carrier should be helpful in those applications as well. In our particular application of the residual stress measurements, assuming the analysis is performed by the fringe counting along a particular direction 6,8,10 without temporal or spatial phase shifting interferometry, the precisely known carrier information becomes very important.…”

“…In our particular interest, we have successfully demonstrated that local spot heating and subsequent surface strain measurements by speckle correlation interferometry can provide quantitative information about the object stress. [6][7][8][9][10][11] Recently Zhang 12 applied speckle correlation interferometry to determine surface strains induced by blind-hole-drilling procedure of the residual stress evaluation. All these experiments have been in laboratory conditions with samples under known stress situations.…”

Residual stress measurement using a radial in-plane speckle interferometer and laser annealing: preliminary results

“…The application of local heating for releasing the residual stress combined with DSPI for measuring the in-plane displacement component was recently presented by Perchersky et al 13,14 Using preloaded test specimens under uniaxial tension and a simple theoretical model to explain the annealing process, through a series of experiments these authors demonstrated the validity of this approach for releasing residual stresses. As the loading direction was known, a standard dual-beam interferometer with a sensitivity along that direction was used in these works.…”