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Proceedings Paper

Study of mechanical characteristics of window security films by phase-stepping photoelasticity
Author(s): E. Stoykova; W. Van Paepegem; S. De Pauw; J. Degrieck; V. Sainov
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Paper Abstract

The goal of this study is to apply photoelasticity for analysis of the mechanical behavior of thermoplastic polyester window security films. More specifically, the change of the photoelastic pattern for film samples with mechanical stress concentrators (holes and cracks) under tensile load is observed. For the purpose, the samples are covered with photoelastic birefringent PhotoStress® coatings. Being subjected to a tensile external load, the film transfers the strains over its surface to the coating. The latter are observed as interference fringes - isochromatic fringes, which exhibit the difference of the principal strains and isoclinic fringes, which characterize principal strains orientation. The photoelastic measurements were performed with a circular reflection polariscope with a white light and monochromatic illumination (575 nm). In the second case, two-loads phase-shifting technique is used for digital retrieval of isochromatics and isoclinics by successive acquisition of two pairs of four fringe patterns obtained at four different configurations of the optical elements of the polariscope. Since the specifics of the studied thermoplastic materials requires simultaneous recording of the phase-shifted patterns in the non-linear part of their loading curve, we propose an optical arrangement for real-time recording as a future development for solution of non-linear dynamic tasks.

Paper Details

Date Published: 19 December 2008
PDF: 11 pages
Proc. SPIE 7027, 15th International School on Quantum Electronics: Laser Physics and Applications, 70270P (19 December 2008); doi: 10.1117/12.822465
Show Author Affiliations
E. Stoykova, Central Lab. of Optical Storage and Processing of Information (Bulgaria)
W. Van Paepegem, Ghent Univ. (Belgium)
S. De Pauw, Ghent Univ. (Belgium)
J. Degrieck, Ghent Univ. (Belgium)
V. Sainov, Central Lab. of Optical Storage and Processing of Information (Bulgaria)


Published in SPIE Proceedings Vol. 7027:
15th International School on Quantum Electronics: Laser Physics and Applications
Tanja Dreischuh; Elena Taskova; Ekaterina Borisova; Alexander Serafetinides, Editor(s)

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