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42145 Some novel approaches for the nondestructive inspection of composites
42366
Brosey, W.D.; Cantreall, J.L.
Comparison of ultrasonic flaw-detection analysis for spherical composite test specimens using two data-acquisition techniques Material Evaluation, Vol. 47, No. 8, pp, 916-920 (Aug. 1989) Gated data-acquisition and waveform-digitization techniques arc compared for reliability in ultrasonic flaw-detection analysis of composite spheres. 42352
Bergmann, H. W.
Mechanical properties and damage mechanisms of carbonfiherreinforced composites. Compression loading Deutsche Forschungs- und Versuchsanstalt fuer Luftund Raumfahrt e.V. (Fed. Rep. Germany), TIB-B89-80185, 422 pp. (1988) The fracture properties and the damage mechanisms of unnotched and notched graphite/epoxy laminates were investigated by experimental tests and by analytical models. X-ray radiography, ultrasonic C- scanning, acoustic emission techniques and a reflection method were used to characterize and monitor the damage states. Sectioning of the laminates was performed to compare the global laminate properties with macro-and microscopic modes of failure. The understanding of the damage mechanisms and fatigue behavior of carbon fiber-reinforced composites was enhanced. 42229
Skorobogat, L.I.; lvanov, V.G.
Mathematical provisions for the automated system of ultrasonic inspection Soviet Journal of Non-Destructive Testing, Vol. 24, No. 11, pp. 780786 (Jul. 1989) The article reviews the program means of the automated system of ultrasonic inspection of products made of composite materials and their possibilities. The system makes it possible to inspect large objects with scanning in steps of up to 1 mm and subsequent visualization of defects in the form of C-type scans. 42202
Gandhe, G. V.; Griffin, O.H., Jr.
Post-impact characterization of interleaved composite materials SAMPE Quarterly, Vol. 20, No. 4, pp. 55-58 (Jul. 1989) Efforts were made to study the improvement in impact resistance of graphite/epoxy composite laminates by incorporation of a thin thermoplastic film (interleaf) between every graphite/epoxy layer. Test specimens of interleaved and non-interleaved graphite/epoxy prepreg were subjected to low velocity instrumented drop weight impact. The extent and nature of the damage was studied using ultrasonic C-scan. Onset and growth of delamination damage was evaluated at a number of impact energy levels. Residual tensile strength of the test specimens was measured. The interleaved laminates exhibited much tess delamination damage for a given impact energy. 42150
Odorico, J.; Lecuru, D.; Choffy, J.P.
Shock detection in composite structures. Test report 48-915/F) (In French) Societe Nationale Industrielle Aerospatiale, Suresnes (France) N8912683, 65 pp. (26 May 1988) Nondestructive methods used to evaluate damage after impact in composite materials are compared. The methods include high frequency ultrasonics, low frequency ultrasonics (400 kHz), and eddy currents. The evaluation of the delaminated surface is made accurately with the high frequency ultrasonics only. In that case the ultrasonics are coupled with a SIAM R-Theta system. No method allows the detection of stiffener break. That is possible using X-ray control. 42145
Berger, H.; Jones, T.S.
Some novel approaches for the nondestructive inspection of composites Materials Processes: The Intercept Point, Proceedings of the 20th International SAMPE Conference, Minneapolis (United States), pp. 457- 466. Edited by H.L. Chess and S.P. Prosea, SAMPE (1988) A brief review of the conventional methods for nondestructive testing of composites is presented with emphasis on ultrasonic scanning systems and radiographic inspection. Several novel methods for inspection are discussed. One of these is a backscatter X-ray technique that has particular attraction for the inspection of laminated structures such as a rocket motor case. This one-sided inspection method can provide quantitative information about discontinuity size, depth and density variation. An ultrasonic correlator instrument is described. This continuous wave instrument offers significant enhancement of signal-to- noise response, an advantage gained from the increased signal accumulation time. The correlator offers advantages for the characterization and testing of highly attenuating materials. Other nondestructive inspection methods described include infrared imaging and holographic interferometry, both large area, non-contact inspection methods that provide excellent sensitivity for near-surface discontinuities. 42026
Ensrninger, D.
Ultrasonics Marcel Dekker, Inc., 580 pp. (1988) The textbook, designed for student or graduate engineers discusses the theory and application of ultrasonics as a nondestructive evaluation technique. Following a discussion of elastic wave propagation and transducer design, the author discusses the use of ultrasonics in determining material properties. Nondestructive testing of metals and non-metals is considered as is process control and ultrasonic imaging. High and low intensity applications are covered. Finally ultrasonics based on chemical effects and medical applications are considered.
230
42(tll
Zala, ('.A.; Barrodale, 1.; McRae, K.I.
High resolution deconvolution of ultrasonic traces Signal Processing and Pattern Recognition in Nondestructive Evaluation of Materials, Proceedings of the NATO Advanced Research Workshop, Lac Beauport, Quebec, Canada, 19-22 Aug. 1987. Edited by C.M. Chen, pp. i01-108. Springer-Verlag (19881 Ultrasonic inspection techniques arc of considerable importance in the nondestructive evaluation of laminar and composite materials. In the detection and localization of flaws, it is frequently desirable to enhance the resolution of the raw B-scan data. In this report we describe the principles and performance of procedures for improving the temporal resolution of the data. The methods are one-dimensional and arc applied to successive traces (A-scans). 41990
Wooh, S.C.; Daniel, I.M.
Enhancement techniques for ultrasonic imaging of damage in composite materials New Directions in the Nondestructive Evaluation of Advanced Materials. Winter Annual Meeting of the American Society of Mechanical Engineers, Chicago, Illinois, 27 Nov. - 2 Dec. 1988. pp. 53-62. American Society of Mechanical Engineers, New York (1989) Enhancement techniques described include contrast stretching and median filtering, histogram equalization, thresholding, dynamic thresholding, thresholding depending on boundary characteristics, one-dimensional segmentation and intensity scans with hidden line removal. These enhancement techniques were applied and illustrated for five different types of damage in graphite/epoxy composite materials: (l) Embedded film patch in quasi-isotropic laminate. (2) Impact damage in quasi- isotropic laminate, (3) Matrix cracking due to static loading of crossply laminate, (4) Fatigue damage in crossply laminate, and (5) Thermally induced cracks in a thick crossply laminate. There is no single technique that is optimum in all cases. A Suitable combination of techniques must be selected for optimum image quality. 41980
Moon, S.M.
Damage assessment by acousto-ultrasonic technique in composites Dissertation Abstracts International, Vol. 49, No. 11, p. 5001 (May 1989) The main objective of this research was to refine the acousto- ultrasonic technique for application to the damage assessment and characterization of composite materials. In the application of the acousto-ultrasonic technique to a graphite/epoxy laminate the dominant wave produced was a symmetric Lamb wave. The wave velocities in all directions can be predicted assuming zero displacement normal to the wave propagation direction. The Lamb wave expression can be used to predict the wave velocity in the laminate with different ply orientations. The reflections of the tone burst wave from the boundaries of the laminate were identified with the time domain and spectral analysis. The impact damage region was located with a linear location technique. The presence of impact damage was detected by an increase in propagation time. The lower values of signal parameters such as peak amplitude, energy and rms value compared to the unimpacted region confirms the presence of damage. For an S-2 Glass/epoxy cross- ply laminate the theoretically computed first ply failure stress coincides with the experimental indication of the first ply failure. The initiation of plycracking was also detected by an attenuation of wave parameters such as peak amplitude, energy and FFT amplitude. These parameters were further attenuated with an increase in stress. The reduction in in-plane stiffness with an increase in damage was computed from velocity measurement. 41979
Kwun, H.; Alcazar, D.G.
Evaluation of bond testing equipment for inspection of army advanced composite airframe structures Southwest Research Institute, San Antonio, Texas (United States), AO- A201 815/8/GAR, 48 pp. (Oct. 19881 Forty-one ultrasonic bond testing instruments for non-destructive inspection of composite airframe structures were evaluated based on information available in the literature. In addition, three of these instruments, were evaluated in the laboratory using ten specimens of composite airframe structures supplied by the Army. 41958
Rogovsky, A.J.
Engineering selection of NDT techniques and accept-reject criteria for composites New Directions in the Nondestructive Evaluation of Advanced Materials, Winter Annual Meeting of the American Society of Mechanical Engineers, Chicago, Illinois, 27 Nov, -- 2 Dec. 1988. pp. 45-52. American Society of Mechanical Engineers, New York (1989) Several types of honeycomb and graphite-epoxy composites were investigated to determine appropriate techniques and accept/reject criteria for NDT. Samples with built-in defects of various types, sizes, and locations were designed and fabricated. Ultrasonic. infrared imaging, and x-ray techniques were applied for flaw detection, sizing and characterization. Composite samples with and without defects underwent thermocycling and proof-load tests and were nondestructively evaluated before and after these tests. Correlation of NDE, thermocyeling, and proof-load test results made it possible to define requirements for NDT of composite parts and to develop accept/reject criteria. 41952
Tartary, S.; Fahr, A.; Haddad, Y.
Nondestructive evaluation of adhesively bonded joints using aconstoultrasonics
NDT International August 1990
Brosey, W.D.; Cantreall, J.L.
Comparison of ultrasonic flaw-detection analysis for spherical composite test specimens using two data-acquisition techniques Material Evaluation, Vol. 47, No. 8, pp, 916-920 (Aug. 1989) Gated data-acquisition and waveform-digitization techniques arc compared for reliability in ultrasonic flaw-detection analysis of composite spheres. 42352
Bergmann, H. W.
Mechanical properties and damage mechanisms of carbonfiherreinforced composites. Compression loading Deutsche Forschungs- und Versuchsanstalt fuer Luftund Raumfahrt e.V. (Fed. Rep. Germany), TIB-B89-80185, 422 pp. (1988) The fracture properties and the damage mechanisms of unnotched and notched graphite/epoxy laminates were investigated by experimental tests and by analytical models. X-ray radiography, ultrasonic C- scanning, acoustic emission techniques and a reflection method were used to characterize and monitor the damage states. Sectioning of the laminates was performed to compare the global laminate properties with macro-and microscopic modes of failure. The understanding of the damage mechanisms and fatigue behavior of carbon fiber-reinforced composites was enhanced. 42229
Skorobogat, L.I.; lvanov, V.G.
Mathematical provisions for the automated system of ultrasonic inspection Soviet Journal of Non-Destructive Testing, Vol. 24, No. 11, pp. 780786 (Jul. 1989) The article reviews the program means of the automated system of ultrasonic inspection of products made of composite materials and their possibilities. The system makes it possible to inspect large objects with scanning in steps of up to 1 mm and subsequent visualization of defects in the form of C-type scans. 42202
Gandhe, G. V.; Griffin, O.H., Jr.
Post-impact characterization of interleaved composite materials SAMPE Quarterly, Vol. 20, No. 4, pp. 55-58 (Jul. 1989) Efforts were made to study the improvement in impact resistance of graphite/epoxy composite laminates by incorporation of a thin thermoplastic film (interleaf) between every graphite/epoxy layer. Test specimens of interleaved and non-interleaved graphite/epoxy prepreg were subjected to low velocity instrumented drop weight impact. The extent and nature of the damage was studied using ultrasonic C-scan. Onset and growth of delamination damage was evaluated at a number of impact energy levels. Residual tensile strength of the test specimens was measured. The interleaved laminates exhibited much tess delamination damage for a given impact energy. 42150
Odorico, J.; Lecuru, D.; Choffy, J.P.
Shock detection in composite structures. Test report 48-915/F) (In French) Societe Nationale Industrielle Aerospatiale, Suresnes (France) N8912683, 65 pp. (26 May 1988) Nondestructive methods used to evaluate damage after impact in composite materials are compared. The methods include high frequency ultrasonics, low frequency ultrasonics (400 kHz), and eddy currents. The evaluation of the delaminated surface is made accurately with the high frequency ultrasonics only. In that case the ultrasonics are coupled with a SIAM R-Theta system. No method allows the detection of stiffener break. That is possible using X-ray control. 42145
Berger, H.; Jones, T.S.
Some novel approaches for the nondestructive inspection of composites Materials Processes: The Intercept Point, Proceedings of the 20th International SAMPE Conference, Minneapolis (United States), pp. 457- 466. Edited by H.L. Chess and S.P. Prosea, SAMPE (1988) A brief review of the conventional methods for nondestructive testing of composites is presented with emphasis on ultrasonic scanning systems and radiographic inspection. Several novel methods for inspection are discussed. One of these is a backscatter X-ray technique that has particular attraction for the inspection of laminated structures such as a rocket motor case. This one-sided inspection method can provide quantitative information about discontinuity size, depth and density variation. An ultrasonic correlator instrument is described. This continuous wave instrument offers significant enhancement of signal-to- noise response, an advantage gained from the increased signal accumulation time. The correlator offers advantages for the characterization and testing of highly attenuating materials. Other nondestructive inspection methods described include infrared imaging and holographic interferometry, both large area, non-contact inspection methods that provide excellent sensitivity for near-surface discontinuities. 42026
Ensrninger, D.
Ultrasonics Marcel Dekker, Inc., 580 pp. (1988) The textbook, designed for student or graduate engineers discusses the theory and application of ultrasonics as a nondestructive evaluation technique. Following a discussion of elastic wave propagation and transducer design, the author discusses the use of ultrasonics in determining material properties. Nondestructive testing of metals and non-metals is considered as is process control and ultrasonic imaging. High and low intensity applications are covered. Finally ultrasonics based on chemical effects and medical applications are considered.
230
42(tll
Zala, ('.A.; Barrodale, 1.; McRae, K.I.
High resolution deconvolution of ultrasonic traces Signal Processing and Pattern Recognition in Nondestructive Evaluation of Materials, Proceedings of the NATO Advanced Research Workshop, Lac Beauport, Quebec, Canada, 19-22 Aug. 1987. Edited by C.M. Chen, pp. i01-108. Springer-Verlag (19881 Ultrasonic inspection techniques arc of considerable importance in the nondestructive evaluation of laminar and composite materials. In the detection and localization of flaws, it is frequently desirable to enhance the resolution of the raw B-scan data. In this report we describe the principles and performance of procedures for improving the temporal resolution of the data. The methods are one-dimensional and arc applied to successive traces (A-scans). 41990
Wooh, S.C.; Daniel, I.M.
Enhancement techniques for ultrasonic imaging of damage in composite materials New Directions in the Nondestructive Evaluation of Advanced Materials. Winter Annual Meeting of the American Society of Mechanical Engineers, Chicago, Illinois, 27 Nov. - 2 Dec. 1988. pp. 53-62. American Society of Mechanical Engineers, New York (1989) Enhancement techniques described include contrast stretching and median filtering, histogram equalization, thresholding, dynamic thresholding, thresholding depending on boundary characteristics, one-dimensional segmentation and intensity scans with hidden line removal. These enhancement techniques were applied and illustrated for five different types of damage in graphite/epoxy composite materials: (l) Embedded film patch in quasi-isotropic laminate. (2) Impact damage in quasi- isotropic laminate, (3) Matrix cracking due to static loading of crossply laminate, (4) Fatigue damage in crossply laminate, and (5) Thermally induced cracks in a thick crossply laminate. There is no single technique that is optimum in all cases. A Suitable combination of techniques must be selected for optimum image quality. 41980
Moon, S.M.
Damage assessment by acousto-ultrasonic technique in composites Dissertation Abstracts International, Vol. 49, No. 11, p. 5001 (May 1989) The main objective of this research was to refine the acousto- ultrasonic technique for application to the damage assessment and characterization of composite materials. In the application of the acousto-ultrasonic technique to a graphite/epoxy laminate the dominant wave produced was a symmetric Lamb wave. The wave velocities in all directions can be predicted assuming zero displacement normal to the wave propagation direction. The Lamb wave expression can be used to predict the wave velocity in the laminate with different ply orientations. The reflections of the tone burst wave from the boundaries of the laminate were identified with the time domain and spectral analysis. The impact damage region was located with a linear location technique. The presence of impact damage was detected by an increase in propagation time. The lower values of signal parameters such as peak amplitude, energy and rms value compared to the unimpacted region confirms the presence of damage. For an S-2 Glass/epoxy cross- ply laminate the theoretically computed first ply failure stress coincides with the experimental indication of the first ply failure. The initiation of plycracking was also detected by an attenuation of wave parameters such as peak amplitude, energy and FFT amplitude. These parameters were further attenuated with an increase in stress. The reduction in in-plane stiffness with an increase in damage was computed from velocity measurement. 41979
Kwun, H.; Alcazar, D.G.
Evaluation of bond testing equipment for inspection of army advanced composite airframe structures Southwest Research Institute, San Antonio, Texas (United States), AO- A201 815/8/GAR, 48 pp. (Oct. 19881 Forty-one ultrasonic bond testing instruments for non-destructive inspection of composite airframe structures were evaluated based on information available in the literature. In addition, three of these instruments, were evaluated in the laboratory using ten specimens of composite airframe structures supplied by the Army. 41958
Rogovsky, A.J.
Engineering selection of NDT techniques and accept-reject criteria for composites New Directions in the Nondestructive Evaluation of Advanced Materials, Winter Annual Meeting of the American Society of Mechanical Engineers, Chicago, Illinois, 27 Nov, -- 2 Dec. 1988. pp. 45-52. American Society of Mechanical Engineers, New York (1989) Several types of honeycomb and graphite-epoxy composites were investigated to determine appropriate techniques and accept/reject criteria for NDT. Samples with built-in defects of various types, sizes, and locations were designed and fabricated. Ultrasonic. infrared imaging, and x-ray techniques were applied for flaw detection, sizing and characterization. Composite samples with and without defects underwent thermocycling and proof-load tests and were nondestructively evaluated before and after these tests. Correlation of NDE, thermocyeling, and proof-load test results made it possible to define requirements for NDT of composite parts and to develop accept/reject criteria. 41952
Tartary, S.; Fahr, A.; Haddad, Y.
Nondestructive evaluation of adhesively bonded joints using aconstoultrasonics
NDT International August 1990