- Email: [email protected]
53659 USAF research and development programs for aging aircraft
ND T Abstracts were correlated with ultrasonic C-scans, and satisfactory agreement was obtained.
Marioli-Riga, Z.P.; Karanika, A.N.; Philippidis, T.P.; Paipetis, S.A. Damage detection by acousto-ultrasonic location (AUL) 53662
Debonding/Delamination of Composites, Patras (Greece), 24-29 May 1992. pp. 24-1 - 24-3. AGARD Conference Proceedings No. 530 (1992). A new technique based on the Acousto-Ultrasonic (AU) concept is introduced, but instead of extracting information from the externally generated pulsed wave, as with AU, the characteristics of waves reflected from defects are measured. In this way it was possible to identify and locate defected areas in honeycomb panels and thermoplastic carbon fibre laminates. The results were correlated with ultrasonic C-scans. and satisfactory agreement was obtained.
Lincoln, J.W. USAF research and development programs for aging aircraft
53659
5th International Conference on Structural Airworthiness of New and Aging Aircraft. Hamburg (Federal Republic of Germany), 16-18 Jun. 1993. pp. 169-173. DGLR (1993), ISBN 3922010792. For the past thirty-five years the United States Air Force has used the USAF Aircraft Structural Integrity Program (ASIP) to maintain safe and economical operation of aging aircraft. It is the purpose of this paper to discuss the USAF research and development programs in aging aircraft and to identify the technology areas where the USAF and the FAA are cooperating to find solutions to current problems.
Dewhurst, RA.; He, R.; Shah, Q. Defect visualization in carbon fiber composite using laser 53501
ultrasound Materials Evaluation, Vol. 51, No. 8, pp. 935-940 (Aug. 1993) A non-contacting laser ultrasound system has been developed to visualize laminar defects in carbon fiber composite materials. Lasergenerated ultrasound (LGU) was produced from a Nd:Y AG Q-switched laser. Ultrasound was detected with the use an actively stabilized Fabry-Perot interferometer using a 400 mW argon-ion laser source. It detected ultrasound in a typical frequency range of 1 to 10 MHz. Through-transmission C-scan measurements were made in carbon fiber composite materials of thickness 1 to 20 mm. Peak-to-peak amplitudes of the first longitudinal ultrasonic pulse were measured, with attenuation used as the basis of defect examination. Digital filtering was adopted to enhance defect visibility. Results showed that images with size resolution better than 1 mm can be achieved. Such measurements take into account any variation of surface reflectivity which can arise in industrial materials.
Komsky, I.N.; Achenbach, J.D. A self-calibrating ultrasonic technique for nondestructive inspection of airplane s t r u c t u r e s 53144
"Quality Through NDT: A Partner for Success". 1992 ASNT Fall Conference and Quality Testing Show, Chicago, Illinois (United States), 16-20 Nov. 1992. pp. 58-61 ASNT (1993) A self-calibrating technique is applied to the detection of fatigue cracks in aircraft structures. Experimental results have been obtained for Lamb wave interference with fatigue cracks and EDM notches around rivet holes in different layers of a lap joint. The self-calibrating technique has also been tested on a bolted joint for crack detection in the second (bottom) layer. Discrete macrocracks simulated by EDM notches have been characterized in the second layer of a specimen that modeled a spar-cap/strap connection in the tail section of the DC-10.
Deponti, F; Tonolini, F; Angrilli, F; Saracco, F Acoustic microscopy in composite materials testing
52728
Nondestructive Characterization of Materials V, Karuizawa (Japan), 27- 30 May 1991. pp 803-811. Edited by T. Kishi, T. Saito, C. Ruud and R Green. Iketana Science and Technology Foundation (1993) An application of acoustic microscopy to non-destructive characterization of composite materials used in aerospace structures is described. The inspected materials are multilayer graphite epoxy laminated. The specimens are built up with alternated layers of different orientations. The examined samples are damaged through impacts of different energy levels. These impacts produce defects such as delaminations and fiber fractures. The results show that the different layers of composite material may be identified and the location and extension of damage are evidence.
156
NDT&E International 1994 Volume 27, Number 3
52716 Woodmansee, W E Ultrasonic inspection of graphite composite aircraft structures Nondestructive Characterisation of Materials V, Karuizawa (japan), 27- 30 May 1991. pp 1049 - 1060. Edited by T Kishi, T Saito, C Ruud and R Green. Iketani Science and Technology Foundation (1993) Ultrasonic methods are extensively used for inspecting composite aircraft structures. These inspections play two principal roles: (I) Correction of fabrication and assembly problems through testing of prototype structures. (2) Monitoring of production composite fabrication processes. Through transmission ultrasonic (TTU) systems for testing secondary aircraft composite components built with honeycomb construction will be described. A pulse-echo (PE) technique developed for composite laminates will also be shown. Examples will be given of preproduction and production problems detected with these techniques. 52173 Morton, H.J.; Bishop, B.C.; Clark, G. Use of A R L portable C - s c a n n e r on F/A-18 composite components Non-Destructive Testing-Australia, Vol. 29, No. 4, pp. 98-101, (Jul.- Aug. 1992) The system has been demonstrated to he capable of assessing quickly and accurately areas of Iocalised damage in graphite/epoxy (G/E) laminate components. The equipment demonstrated significant advantages over hand-scanning for relatively quick, accurate and reliable scans of large components. 52165 Doyle, P.A.; Scala, C.M. T o w a r d laser-ultrasonic characterization of an orthotropicisotropic interface Journal of the Acoustical Society of America, Vol. 93, No. 3, pp. 1385- 1392 (Mar. 1993) This paper describes work ultimately directed toward an assessment of the adhesive bond strength between the composite overlay and the aircraft substrate. The potential use of leaky interface waves for the adhesive bond assessment is addressed, by considering the existence of such waves along the boundary between an orthotropic composite overlay and an isotropic metallic substrate. Numerical procedures are described to calculate complex leaky interface wave velocities, for propagation parallel or perpendicular to the fibers. It is shown that seven of the nine orthotropic elastic constants are required to calculate these velocities. Next, a new scheme is proposed to determine the seven required orthotropic elastic constants, based on laser-ultrasonic line sources and interferometric detection. 52160 Anon Use of ultrasonics for Oleo compression m e a s u r e m e n t s on a S-70B-2 (Seahawk) helicopter Aeronautical Research Labs., Melbourne (Australia), AD-A256 315/3/GAR, 20pp. (Jul. 1992) Dynamic measurements were conducted to acquire data for the development of a mathematical model of the undercarriage of a S-70B-2 (Seahawk) helicopter. The principal measuring instrumentation consisted of LVDT's and ultrasonic transducers. This memorandum discusses a Ranging Ultrasonic Transducer which was developed to overcome the inherent and excessive recovery time delay of the ultrasonic transducers when subjected to out-of-range distance operations during the flight trials.
Pooh, C.; Komorowski, J.P.; Gould, R.W.; Chapman, C.E. Quantitative assessment of impact damage in composites 52157
International Conference on Aircraft Damage Assessment and Repair, Melbourne (Australia), 26-28 Aug. 1991. pp. 54-58. The Institution o f Engineers (1991) The effect of impact damage resulting from drop-weight impact testing of AS4/3501-6 laminates with a quasi-isotropic lay-up on residual compressive strength was quantitatively assessed. The damage based on the volume of the material affected by the impact was determined nondestructively using an ultrasonic time-of-flight C-scanning technique. Compression-after-impact tests were performed which provided data for correlating damage volume to residual compressive strength. During compression testing, damage progression was continuously monitored using a photoelastic method and D-sight. The isochromatic pauems observed, which are proportional to the maximum shear strains, were found to be consistent with the directions of damage growth under load. The continuous change in the surface curvature of the impact damaged specimens showing localized buckling under the increasing compression load was observed under D-sight.
Marioli-Riga, Z.P.; Karanika, A.N.; Philippidis, T.P.; Paipetis, S.A. Damage detection by acousto-ultrasonic location (AUL) 53662
Debonding/Delamination of Composites, Patras (Greece), 24-29 May 1992. pp. 24-1 - 24-3. AGARD Conference Proceedings No. 530 (1992). A new technique based on the Acousto-Ultrasonic (AU) concept is introduced, but instead of extracting information from the externally generated pulsed wave, as with AU, the characteristics of waves reflected from defects are measured. In this way it was possible to identify and locate defected areas in honeycomb panels and thermoplastic carbon fibre laminates. The results were correlated with ultrasonic C-scans. and satisfactory agreement was obtained.
Lincoln, J.W. USAF research and development programs for aging aircraft
53659
5th International Conference on Structural Airworthiness of New and Aging Aircraft. Hamburg (Federal Republic of Germany), 16-18 Jun. 1993. pp. 169-173. DGLR (1993), ISBN 3922010792. For the past thirty-five years the United States Air Force has used the USAF Aircraft Structural Integrity Program (ASIP) to maintain safe and economical operation of aging aircraft. It is the purpose of this paper to discuss the USAF research and development programs in aging aircraft and to identify the technology areas where the USAF and the FAA are cooperating to find solutions to current problems.
Dewhurst, RA.; He, R.; Shah, Q. Defect visualization in carbon fiber composite using laser 53501
ultrasound Materials Evaluation, Vol. 51, No. 8, pp. 935-940 (Aug. 1993) A non-contacting laser ultrasound system has been developed to visualize laminar defects in carbon fiber composite materials. Lasergenerated ultrasound (LGU) was produced from a Nd:Y AG Q-switched laser. Ultrasound was detected with the use an actively stabilized Fabry-Perot interferometer using a 400 mW argon-ion laser source. It detected ultrasound in a typical frequency range of 1 to 10 MHz. Through-transmission C-scan measurements were made in carbon fiber composite materials of thickness 1 to 20 mm. Peak-to-peak amplitudes of the first longitudinal ultrasonic pulse were measured, with attenuation used as the basis of defect examination. Digital filtering was adopted to enhance defect visibility. Results showed that images with size resolution better than 1 mm can be achieved. Such measurements take into account any variation of surface reflectivity which can arise in industrial materials.
Komsky, I.N.; Achenbach, J.D. A self-calibrating ultrasonic technique for nondestructive inspection of airplane s t r u c t u r e s 53144
"Quality Through NDT: A Partner for Success". 1992 ASNT Fall Conference and Quality Testing Show, Chicago, Illinois (United States), 16-20 Nov. 1992. pp. 58-61 ASNT (1993) A self-calibrating technique is applied to the detection of fatigue cracks in aircraft structures. Experimental results have been obtained for Lamb wave interference with fatigue cracks and EDM notches around rivet holes in different layers of a lap joint. The self-calibrating technique has also been tested on a bolted joint for crack detection in the second (bottom) layer. Discrete macrocracks simulated by EDM notches have been characterized in the second layer of a specimen that modeled a spar-cap/strap connection in the tail section of the DC-10.
Deponti, F; Tonolini, F; Angrilli, F; Saracco, F Acoustic microscopy in composite materials testing
52728
Nondestructive Characterization of Materials V, Karuizawa (Japan), 27- 30 May 1991. pp 803-811. Edited by T. Kishi, T. Saito, C. Ruud and R Green. Iketana Science and Technology Foundation (1993) An application of acoustic microscopy to non-destructive characterization of composite materials used in aerospace structures is described. The inspected materials are multilayer graphite epoxy laminated. The specimens are built up with alternated layers of different orientations. The examined samples are damaged through impacts of different energy levels. These impacts produce defects such as delaminations and fiber fractures. The results show that the different layers of composite material may be identified and the location and extension of damage are evidence.
156
NDT&E International 1994 Volume 27, Number 3
52716 Woodmansee, W E Ultrasonic inspection of graphite composite aircraft structures Nondestructive Characterisation of Materials V, Karuizawa (japan), 27- 30 May 1991. pp 1049 - 1060. Edited by T Kishi, T Saito, C Ruud and R Green. Iketani Science and Technology Foundation (1993) Ultrasonic methods are extensively used for inspecting composite aircraft structures. These inspections play two principal roles: (I) Correction of fabrication and assembly problems through testing of prototype structures. (2) Monitoring of production composite fabrication processes. Through transmission ultrasonic (TTU) systems for testing secondary aircraft composite components built with honeycomb construction will be described. A pulse-echo (PE) technique developed for composite laminates will also be shown. Examples will be given of preproduction and production problems detected with these techniques. 52173 Morton, H.J.; Bishop, B.C.; Clark, G. Use of A R L portable C - s c a n n e r on F/A-18 composite components Non-Destructive Testing-Australia, Vol. 29, No. 4, pp. 98-101, (Jul.- Aug. 1992) The system has been demonstrated to he capable of assessing quickly and accurately areas of Iocalised damage in graphite/epoxy (G/E) laminate components. The equipment demonstrated significant advantages over hand-scanning for relatively quick, accurate and reliable scans of large components. 52165 Doyle, P.A.; Scala, C.M. T o w a r d laser-ultrasonic characterization of an orthotropicisotropic interface Journal of the Acoustical Society of America, Vol. 93, No. 3, pp. 1385- 1392 (Mar. 1993) This paper describes work ultimately directed toward an assessment of the adhesive bond strength between the composite overlay and the aircraft substrate. The potential use of leaky interface waves for the adhesive bond assessment is addressed, by considering the existence of such waves along the boundary between an orthotropic composite overlay and an isotropic metallic substrate. Numerical procedures are described to calculate complex leaky interface wave velocities, for propagation parallel or perpendicular to the fibers. It is shown that seven of the nine orthotropic elastic constants are required to calculate these velocities. Next, a new scheme is proposed to determine the seven required orthotropic elastic constants, based on laser-ultrasonic line sources and interferometric detection. 52160 Anon Use of ultrasonics for Oleo compression m e a s u r e m e n t s on a S-70B-2 (Seahawk) helicopter Aeronautical Research Labs., Melbourne (Australia), AD-A256 315/3/GAR, 20pp. (Jul. 1992) Dynamic measurements were conducted to acquire data for the development of a mathematical model of the undercarriage of a S-70B-2 (Seahawk) helicopter. The principal measuring instrumentation consisted of LVDT's and ultrasonic transducers. This memorandum discusses a Ranging Ultrasonic Transducer which was developed to overcome the inherent and excessive recovery time delay of the ultrasonic transducers when subjected to out-of-range distance operations during the flight trials.
Pooh, C.; Komorowski, J.P.; Gould, R.W.; Chapman, C.E. Quantitative assessment of impact damage in composites 52157
International Conference on Aircraft Damage Assessment and Repair, Melbourne (Australia), 26-28 Aug. 1991. pp. 54-58. The Institution o f Engineers (1991) The effect of impact damage resulting from drop-weight impact testing of AS4/3501-6 laminates with a quasi-isotropic lay-up on residual compressive strength was quantitatively assessed. The damage based on the volume of the material affected by the impact was determined nondestructively using an ultrasonic time-of-flight C-scanning technique. Compression-after-impact tests were performed which provided data for correlating damage volume to residual compressive strength. During compression testing, damage progression was continuously monitored using a photoelastic method and D-sight. The isochromatic pauems observed, which are proportional to the maximum shear strains, were found to be consistent with the directions of damage growth under load. The continuous change in the surface curvature of the impact damaged specimens showing localized buckling under the increasing compression load was observed under D-sight.