The method of tandem speckle photography has been successfully applied to the measurement of vibratory strain on an actual turbine blade. Several procedural changes have been implemented in the mechanics of the experimental process to both improve and simplify the technique: 1) Increasing to four toe number of specklegram pairs to reduce the effect of data errors by overdetermination; 2) Increasing the spacing between specklegram pairs; 3) Locating the point of zero speckle motion between the pair of tandem specklegrams; and 4) Improing equipment stability and measurement of the sensitivity vectors. In addition, the data reduction program nas been modified to calculate standard errors for the strain parameters. Finally, a computeraided TV analysis of toe nalo fringes, as recorded photographically, has been employed. Tne influence of the above changes on performing strain measurements, via the tandem speckle photographic process, will be reported, along with comparisons between the results obtained with computeraided TV analysis acid manual evaluation of the halo fringe data.

Date Published: 20 May 1980
PDF: 7 pages
Proc. SPIE 0210, 2nd European Congress on Optics Applied to Metrology, (20 May 1980); doi: 10.1117/12.958312

Published in SPIE Proceedings Vol. 0210:
2nd European Congress on Optics Applied to Metrology
Michel H. Grosmann; Patrick Meyrueis, Editor(s)