ISSN:
1573-4862
Keywords:
Holographic inspection
;
local thinning
;
clamping boundary conditions
Source:
Springer Online Journal Archives 1860-2000
Topics:
Electrical Engineering, Measurement and Control Technology
,
Mathematics
Notes:
Abstract This paper describes the use of double-exposure holography on the detection and assessment of plates containing locally thinned regions as artificial defects. The artificial defect is programmed by thinning locally a plate to various depths with a milling cutter. During testing, the plate, illuminated by an expanded laser beam, is clamped along its periphery and an incremental uniform pressure applied between two exposures on the holographic plate. Local thinning is revealed from anomaly in the reconstructed fringe pattern—the boundary of the anomalous fringes is larger than the boundary of the actual artificial defect, and the amount of thinning is deduced from the number of fringes within the boundary. Artificial defects with eccentric local thinning are more readily revealed from the reconstructed fringe pattern than the artificial centric defects. A simple theoretical model is developed so that when the experimental fringe-counts are compared with the theoretical ones, any discrepancy between them reveals not only the presence of centric and eccentric artificial flaws but also their sizes and depths.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00568291
Permalink