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Damage detection in woven-composite materials using embedded fiber optic sensors
N DT Abstracts
speckle interference patterns (also called holographic speckle patterns) of a rapidly deforming body which is doubly illuminated by a laser light source. The time sequence of speckle icatterns is recorded by means of a high-speed camera on an ultra-sensitive 3~:-mm film. The developed negatives are then digitized by a CCd camera into an image processing system.
52024 Steckenrider, J.C.; Wagner, J.W. C o m p u t e d speckle decorrelation (CSD) a n d its application for fatigue d a m a g e monitoring Review of Progress in Quantitative Nondestructive Evaluation, Brunswick, Maine (United States), 28 Jul.-2 Aug. 1991. Vol. I IA, pp. 487-494. Edited by D.O. Thompson and D.E. Chimenti. Plenum Press (1992) Non-contact surface deformation analysis and mapping can be conducted using a video-based laser speckle technique, at speeds approaching video frame rates. The technique, known as Computed Speckle Decorrelation (CSD), uses the speckle decorrelation associated with surface deformation. CSD means that faster and more quantitative analysis of the progression of fatigue damage in thick graphite/epoxy composite materials is now possible, than was previously available using film-based techniques. CSD combines speckle decorrelation work with real time computer techniques. This study used CSD to monitor fatigue degradation in 2024-T4 aluminium, subjected to reverse bending fatigue.
54054 Fanton, J.T.; Opsal, J.; Willenborg, D.L.; Kelso, S.M.; Rosencwaig, A. Beam profile refiectometry: a new technique for thin film measurement Review of Progress in Quantitative Nondestructive Evaluation, La Jolla, California (United States), 19-24 Jul. 1992. Vol. 12A, pp. 387-394. Edited by D.O. Thompson and D.E. Chimenti. Plenum Press (1993). ISBN 0-306-44483-6. The information present in the intensity profile of a highly focussed, linearly polarized beam makes the BPR a powerful film measurement technique. The shape and amplitude information in the $ and P profiles of angular reflectivity enable us to determine not only the thickness of a simple film, but also the refractive index, extinction coefficient or even the thicknesses of other films in a multi-layer stack. These measurements all occur in a submicron area making possible measurements on product wafers.
50521 Radha, T.S.; Ramprasad, B.S. M e a s u r e m e n t of the t h e r m a l stress in specularly reflecting thin films using real-time holographic i n t e r f e r o m e t r y Nondestructive Testing and Evaluation, Vol. 8-9, Pt. 2, (1992) Proceedings of the 5th International Symposium on Nondestructive Characterization of Materials, Karuizawa (Japan), 27-30 May 1991. pp. 949-957. Edited by T. Kishi, T. Saito, C, Ruud, and R. Green. In this paper a method of measurement of thermal stress of thin films using real-time holographic interferometry is described, with particular emphasis on specularly reflecting thin films. A few thin film-substrate systems have been used for the measurements. For the copper film on brass substrate and silver on glass theoretical and experimental results are found to agree reasonably well at different temperatures. For the cases of aluminium film and magnesium fluoride film on glass there is a wide discrepancy. However it is pointed out that experimental values are closer to reality.
53807 Ehrlich, M.I.; Stec~[enrider, J.S.; Wagner, J.W. High speed holographic " c i n e m a t o g r a p h y " with f r a m e rates a p p r o a c h i n g 25 nanosecon~ds lntefferometry Applications. Proceedings of Meeting at San Diego, California (United States), 22-23 Jul. 1992. pp. 270-276. Edited by R.J. Pryutriewicz, G.M. Bacon and W.P.C Juptner. SPIE. Vol. 1756 (1993) ISBN 0-8194-0929-4 A holographic recording system has been developed in which a single pulse from a frequency doubled Nd:YAG laser is repeatedly spit and delayed to provide up ~ 10 pulses which are separated both in time and in space. A custom graded beam splitter is used to help insure near equal amplitude of all ten pulses. A White cell provides adjustable delay between the sequential outputs of tbe system over a range from 28 to 170 nanoseconds. By appropriate design of the holographic recording geometry, up to ten distinct holographic frames may be recorded in sequence on a single 4" x 5" film plate. Using the system, studies have been performed on the dynamics of detonation of 100 micron explosive particles and on the acceleration and growth of cracks in brittle materials. CW reconstruction of each holographic frame permits microscopic examination of the reconstructed images so that precise measurements of shock front or crack length may be made as a function of time.
50270 Yamaguchi, I.; Takemori, T.; Kobayashi, K. Biaxiai laser speckle strain gauge (In Japanese: English Abstract) Journal of JSNDI, Vol. 39, No. 8, pp. 682-686 (Aug. 1990) The laser speckle stain gauge, which measures surface strain in a noncontacting and automatic way by optoelectronically detecting and comparing speckle displacements at two symmetrical scattering angles, has been extended to a biaxial configuration, lnplane strains along the orthogonal directions have been measured by using four linear image sensors and high speed correlators with the sensitivity of a few tens of microstrains and a time response of a hundred Hz. The instrument has also been applied to simple and quick determination of Poisson's ratio of polymer films at various loading frequencies.
53804 Dovgalenko, G.Y.; Kadura, S.A. Application of hiologicall p h o t o p o l y m e r to nondestructive testing Interferometry Applications Proceedings of Meeting at San Diego, California (United States), 22-23 Jul. 1992. pp. 227-232. Edited by R.J. Pryutriewicz, G.M. Bacon and W.P.C Juptner. SPIE. Vol. 1756 (1993) 1SBN 0-8194-0929-4. The present paper com;iders the results of investigation of photopolymeric films "Biochea~n" as a reversible media to dynamical holographic interferometry. The optimized condition to writing-readout of hologram were obtained. The n=,sultsof nondestructive testing of materials based on adaptive bolographic interferometer using "Biochrom" are presented.
50268 Musilova,J.; Ohlidal, I. Influence of defects of thin films on d e t e r m i n i n g t h e i r thickness by the method based on white light interference Journal of Physics D. Applied Physics, Vol. 25, No. 7, pp. i 131-1138 (14 Jul. 1992) The usefulness of the thin film thickness determination method based on the principle of white light interference could he limited not only by parameters characterizing the optical system itself (optical constants of the measured and reference systems, the measured thickness of the thin film of interest) but also by other additional effects such as inhomogeneity of optical constants of the measured film, roughness of the boundaries and the existence of surface or interface layers. These effects are discussed.
52779 Radha, T.S; Rampr,~sad, B.S M e a s u r e m e n t of the t h e r m a l stress in specularly reflecting thin films using real-time holographic i n t e r f e r o m e t r y Nondestructive Characteri;,ation of Materials V, Karuizawa (Japan), 27- 30 May 1991. pp 949-957. Edited by T. Kishi, T. Saito, C. Ruud and R. Green. Iketani Science and Technology Foundation (1993) A method of measurement of thermal stress of thin films using real-time holographic intefferometry is described, with particular emphasis on specolarly reflecting thin films. A few thin film-substrate systems have been used for the measurements. For the copper film on brass substrate and silver on glass theoretical and experimental results are found to agree reasonably well at different temperatures. For the cases of aluminium film and magnesium fluoride film on gla,gsthere is a wide discrepancy. However it is pointed out that experimental values are closer to reality.
Bonniau, P.; Chazelas, J.; Lecuellet, J.; Gendre, F.; Turpin, M.; Le Pesant, J.-P.; Brevignon, M. 50002
Damage
detection
in
woven-composite
materials
using
embedded fiber optic sensors Fiber Optic Smart Structures and Skins IV, Massachusetts, Boston (United States), 5-6 Sep. 1991. pp. 52-63. Vol. 1588. SPIE (1991) This paper presents our preliminary results on the use of fiber optic sensors for impact detection on Kevlar-opoxy panels. Interfero- polarimetric measurements have been performed by using two different kinds of polarisation-maintaining optical fibers. The sensitivity of the fibers to internal process stresses and to external impact stresses is discussed with respect to the coating nature. The effect of an over-coating on the fiber sensitivity is also reported, impact-induced delaminations have been observed and the optical response has been adjusted by using an appropriate over-coating.
135
speckle interference patterns (also called holographic speckle patterns) of a rapidly deforming body which is doubly illuminated by a laser light source. The time sequence of speckle icatterns is recorded by means of a high-speed camera on an ultra-sensitive 3~:-mm film. The developed negatives are then digitized by a CCd camera into an image processing system.
52024 Steckenrider, J.C.; Wagner, J.W. C o m p u t e d speckle decorrelation (CSD) a n d its application for fatigue d a m a g e monitoring Review of Progress in Quantitative Nondestructive Evaluation, Brunswick, Maine (United States), 28 Jul.-2 Aug. 1991. Vol. I IA, pp. 487-494. Edited by D.O. Thompson and D.E. Chimenti. Plenum Press (1992) Non-contact surface deformation analysis and mapping can be conducted using a video-based laser speckle technique, at speeds approaching video frame rates. The technique, known as Computed Speckle Decorrelation (CSD), uses the speckle decorrelation associated with surface deformation. CSD means that faster and more quantitative analysis of the progression of fatigue damage in thick graphite/epoxy composite materials is now possible, than was previously available using film-based techniques. CSD combines speckle decorrelation work with real time computer techniques. This study used CSD to monitor fatigue degradation in 2024-T4 aluminium, subjected to reverse bending fatigue.
54054 Fanton, J.T.; Opsal, J.; Willenborg, D.L.; Kelso, S.M.; Rosencwaig, A. Beam profile refiectometry: a new technique for thin film measurement Review of Progress in Quantitative Nondestructive Evaluation, La Jolla, California (United States), 19-24 Jul. 1992. Vol. 12A, pp. 387-394. Edited by D.O. Thompson and D.E. Chimenti. Plenum Press (1993). ISBN 0-306-44483-6. The information present in the intensity profile of a highly focussed, linearly polarized beam makes the BPR a powerful film measurement technique. The shape and amplitude information in the $ and P profiles of angular reflectivity enable us to determine not only the thickness of a simple film, but also the refractive index, extinction coefficient or even the thicknesses of other films in a multi-layer stack. These measurements all occur in a submicron area making possible measurements on product wafers.
50521 Radha, T.S.; Ramprasad, B.S. M e a s u r e m e n t of the t h e r m a l stress in specularly reflecting thin films using real-time holographic i n t e r f e r o m e t r y Nondestructive Testing and Evaluation, Vol. 8-9, Pt. 2, (1992) Proceedings of the 5th International Symposium on Nondestructive Characterization of Materials, Karuizawa (Japan), 27-30 May 1991. pp. 949-957. Edited by T. Kishi, T. Saito, C, Ruud, and R. Green. In this paper a method of measurement of thermal stress of thin films using real-time holographic interferometry is described, with particular emphasis on specularly reflecting thin films. A few thin film-substrate systems have been used for the measurements. For the copper film on brass substrate and silver on glass theoretical and experimental results are found to agree reasonably well at different temperatures. For the cases of aluminium film and magnesium fluoride film on glass there is a wide discrepancy. However it is pointed out that experimental values are closer to reality.
53807 Ehrlich, M.I.; Stec~[enrider, J.S.; Wagner, J.W. High speed holographic " c i n e m a t o g r a p h y " with f r a m e rates a p p r o a c h i n g 25 nanosecon~ds lntefferometry Applications. Proceedings of Meeting at San Diego, California (United States), 22-23 Jul. 1992. pp. 270-276. Edited by R.J. Pryutriewicz, G.M. Bacon and W.P.C Juptner. SPIE. Vol. 1756 (1993) ISBN 0-8194-0929-4 A holographic recording system has been developed in which a single pulse from a frequency doubled Nd:YAG laser is repeatedly spit and delayed to provide up ~ 10 pulses which are separated both in time and in space. A custom graded beam splitter is used to help insure near equal amplitude of all ten pulses. A White cell provides adjustable delay between the sequential outputs of tbe system over a range from 28 to 170 nanoseconds. By appropriate design of the holographic recording geometry, up to ten distinct holographic frames may be recorded in sequence on a single 4" x 5" film plate. Using the system, studies have been performed on the dynamics of detonation of 100 micron explosive particles and on the acceleration and growth of cracks in brittle materials. CW reconstruction of each holographic frame permits microscopic examination of the reconstructed images so that precise measurements of shock front or crack length may be made as a function of time.
50270 Yamaguchi, I.; Takemori, T.; Kobayashi, K. Biaxiai laser speckle strain gauge (In Japanese: English Abstract) Journal of JSNDI, Vol. 39, No. 8, pp. 682-686 (Aug. 1990) The laser speckle stain gauge, which measures surface strain in a noncontacting and automatic way by optoelectronically detecting and comparing speckle displacements at two symmetrical scattering angles, has been extended to a biaxial configuration, lnplane strains along the orthogonal directions have been measured by using four linear image sensors and high speed correlators with the sensitivity of a few tens of microstrains and a time response of a hundred Hz. The instrument has also been applied to simple and quick determination of Poisson's ratio of polymer films at various loading frequencies.
53804 Dovgalenko, G.Y.; Kadura, S.A. Application of hiologicall p h o t o p o l y m e r to nondestructive testing Interferometry Applications Proceedings of Meeting at San Diego, California (United States), 22-23 Jul. 1992. pp. 227-232. Edited by R.J. Pryutriewicz, G.M. Bacon and W.P.C Juptner. SPIE. Vol. 1756 (1993) 1SBN 0-8194-0929-4. The present paper com;iders the results of investigation of photopolymeric films "Biochea~n" as a reversible media to dynamical holographic interferometry. The optimized condition to writing-readout of hologram were obtained. The n=,sultsof nondestructive testing of materials based on adaptive bolographic interferometer using "Biochrom" are presented.
50268 Musilova,J.; Ohlidal, I. Influence of defects of thin films on d e t e r m i n i n g t h e i r thickness by the method based on white light interference Journal of Physics D. Applied Physics, Vol. 25, No. 7, pp. i 131-1138 (14 Jul. 1992) The usefulness of the thin film thickness determination method based on the principle of white light interference could he limited not only by parameters characterizing the optical system itself (optical constants of the measured and reference systems, the measured thickness of the thin film of interest) but also by other additional effects such as inhomogeneity of optical constants of the measured film, roughness of the boundaries and the existence of surface or interface layers. These effects are discussed.
52779 Radha, T.S; Rampr,~sad, B.S M e a s u r e m e n t of the t h e r m a l stress in specularly reflecting thin films using real-time holographic i n t e r f e r o m e t r y Nondestructive Characteri;,ation of Materials V, Karuizawa (Japan), 27- 30 May 1991. pp 949-957. Edited by T. Kishi, T. Saito, C. Ruud and R. Green. Iketani Science and Technology Foundation (1993) A method of measurement of thermal stress of thin films using real-time holographic intefferometry is described, with particular emphasis on specolarly reflecting thin films. A few thin film-substrate systems have been used for the measurements. For the copper film on brass substrate and silver on glass theoretical and experimental results are found to agree reasonably well at different temperatures. For the cases of aluminium film and magnesium fluoride film on gla,gsthere is a wide discrepancy. However it is pointed out that experimental values are closer to reality.
Bonniau, P.; Chazelas, J.; Lecuellet, J.; Gendre, F.; Turpin, M.; Le Pesant, J.-P.; Brevignon, M. 50002
Damage
detection
in
woven-composite
materials
using
embedded fiber optic sensors Fiber Optic Smart Structures and Skins IV, Massachusetts, Boston (United States), 5-6 Sep. 1991. pp. 52-63. Vol. 1588. SPIE (1991) This paper presents our preliminary results on the use of fiber optic sensors for impact detection on Kevlar-opoxy panels. Interfero- polarimetric measurements have been performed by using two different kinds of polarisation-maintaining optical fibers. The sensitivity of the fibers to internal process stresses and to external impact stresses is discussed with respect to the coating nature. The effect of an over-coating on the fiber sensitivity is also reported, impact-induced delaminations have been observed and the optical response has been adjusted by using an appropriate over-coating.
135