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Proceedings Paper

Interferometric strain gage and rosettes extended to out-of-plane deformation measurements
Author(s): Keyu Li
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Paper Abstract

This paper extends an optical strain gage/rosette technique to measure derivatives of out-of- plane displacements. The principle of the technique is interference of light reflected and diffracted from two or three closely spaced indentations on a specimen surface. The technique measures derivatives of in-plane and out-of-plane displacements simultaneously through analyzing the phase shift of the interference fringes. Movement of the interference fringes is monitored by a photodiode system and collected via a microcomputer in real time to obtain the specimen deformations. There are a variety of the indentation configurations. The configuration of two pyramidally shaped indentations enables measurements of one derivative of in-plane and one derivative of out-of-plane displacements. Three indentations with six or eight reflective faces allow determination of three derivatives of in-plane and three derivatives of out-of-plane displacements. The derivatives are with respect to the directions of the indentation separations. The theory of the technique is presented. Associated instrumentation for data acquisition and analysis is also described. Experiments are conducted on a cantilever beam to verify the capability of the technique to measure small deflection angles. The comparative results between measurements and theoretical predictions show that the method is feasible to measure derivatives of out-of-plane displacements.

Paper Details

Date Published: 14 June 1995
PDF: 6 pages
Proc. SPIE 2544, Interferometry VII: Techniques and Analysis, (14 June 1995); doi: 10.1117/12.211888
Show Author Affiliations
Keyu Li, Oakland Univ. (United States)

Published in SPIE Proceedings Vol. 2544:
Interferometry VII: Techniques and Analysis
Malgorzata Kujawinska; Ryszard J. Pryputniewicz; Mitsuo Takeda, Editor(s)

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