Accession Number:

ADA048640

Title:

Quantitative Strain and Stress Determination from Holographic Interferograms.

Descriptive Note:

Final technical rept. 31 Jan-Sep 77,

Corporate Author:

BROWN BOVERI RESEARCH CENTER BADEN (SWITZERLAND)

Report Date:

1977-09-01

Pagination or Media Count:

50.0

Abstract:

The basic problems of quantitative determination of mechanical strain through holographic interferometry are discussed. A solution based on the calculation of local derivatives of the holographically recorded surface displacements is described. This method uses essentially heterodyne holographic interferometry for the quantitative determination of the surface displacement from the fringe pattern in the image plane. With this technique the interference phase can be measured with an accuracy and reproducibility of or - 0.3 deg at any point in the fringe pattern, corresponding to an interpolation of better than .001 of one fringe. Numerical examples are given for the sensitivity and accuracy of surface strain measurements and the determination of bending and torsion. Experimental results for bending and torsion of arbitrarily curved and twisted space beams, such as turbine blades, are reported. Accuracy and agreement with theory are within a few percent. Author

Subject Categories:

  • Metallurgy and Metallography

Distribution Statement:

APPROVED FOR PUBLIC RELEASE