Abstract
This paper presents a fringe-carrier method that eliminates sign ambiguity of transient moire fringes which can be used to automatically determine the relative orders. A fringe carrier is preset in the static state of the specimen and the dynamic in-plane displacements are recorded as the modulation to the frequency of the carrier fringes when the specimen is loaded by impact. According to a modulating criterion developed from the modulation degree, the fringes of the transient moire patterns keep monotonical in orders so that they can be automatically encoded in grey levels by a digital image system. The moire orders purely caused by dynamic loadings are evaluated by subtracting the grey-value of the unmodulated carrier image from that of the modulated carrier images encoded by their orders. With the subtracted moire orders the strain components can be obtained, and, correspondingly, the histograms of dynamic displacement moire images are shown with order variation by image-difference.
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References
Dally J W. An introduction to dynamic photoelasticity.Exp Mech, 1980, 20: 409–416
Theocaris P S. Moire Fringes in Strain Analysis. New York: Pergamon Press, Elmfor, 1969
Parks V J. Geometric moire In: Kobayashi A S. ed. Handbook on Experimental Mechanics, 1st edition, New York: Prentice-Hall, 1987
Yatagai T, Idesawa M, Yamashi Y and Suzuki M. Interactive fringe analysis system, applications to moire contourgram and interferogram. Opt Engng, 1982, 21: 901–906
Becker F, Meier G and Wegner H. Automatic evaluation of interferograms. SPIE 359, 1982: 386–393
Xu Z and Huang YY. Photocarrier method of fringe pattern. Proceedings of conf on Exp Mech, Beijing, 1985, 835–834
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The project supported by Alexander von Humboldt Foundation of Germany and the National Natural Science Foundation of China
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Jing, F., Laermann, K.H. Automatic order-determination of transient in-plane displacement moire patterns. Acta Mech Sinica 9, 86–92 (1993). https://doi.org/10.1007/BF02489166
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DOI: https://doi.org/10.1007/BF02489166