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NDE (nondestructive evaluation) of the space shuttle orbiter thermal protection system: phase 2 final report
ND T Abstracts The use of an NdYAG pulsed laser for generating ultrasonic waves for
NDE in resin matrix composites was investigated. In the case of neat resins it was found that. at normal incidence, about 25 percent of the laser pulse energy is reflected at the incident surface, it was found in energy balance studies that graphite fiber/polymer specimens attenuate the laser beam more than do the neat resins. The increased absorption is in the graphite fibers. The occurrence of laser induced surface damage was also studied. The damage threshold is between 0.06 and 0.07 J/cm. 43421 Hemann, J.H.; Cavano, P.; Kautz, H.; Bowles, K. T r a n s - p l y c r a c k density detection by acouste~-ultrasonics Acousto - Ultrasonics, Theory and Application. Edited by J.C. Duke, Jr., pp. 319-325, Plenum Press, 353pp. (1989). ISBN 0306430134 This paper describes how acousto-ultrasonics can be used to detect trans-ply cracks in graphitedPMR polyimide cruss-ply and woven fabric laminates, which are used in high temperature zones in jet engines. Trans-ply cracks seriously reduce the mechanical strength of the structure. It is shown that the acousto-ultrasonic stress wave factor (SWF) correlates with trans-ply crack density where cracks are created by tensile loading of the material. The SWF is shown to be a practical measure and predictor of crack density in laminated composite materials. 43411
Odell, J.H.
NDT of the c a r b o n fibre composite s t r u c t u r e of the H a r r i e r GR5 in service Reliability in Non-Destructive Testing, Proceedings of the 27th Annual British Conference on Non-Destructive Testing, Portsmouth (United Kingdom), 12-15 Sep. 1988. pp. 249-259. Edited by C. Brook and P.D. Hanstead. Pergamon Press, 1989. The RAF now faces the problems of operating aircraft with major components of Carbon Fibre Composite (CFC) in particular the Harrier OR5. Likely forms of damage which may occur in service have been identified, and a joint trial with RAE Farnborough has beencarried out on a representative CFC structure. Appropriate methods of Non Destructive Testing (NDT) have been identified and trials have been carried out on candidate NDT equipments. Service experience of NDT related problems with Harrier CFC structure indicates the minimal additional equipment will be required to meet our needs. 43392 Chern, EJ.: Djordjevic, B.B. N o n i n t r u s i v e u l t r a s o n i c low-liquid-level sensor Materials Evaluation, Vol. 48, No. 4, pp. 481-485 (Apr. 1990) A nonintrusive ultrasonic sensor system for monitoring the fuel level in the liquid propellant tanks of space launch vehicles has been developed and tested, in this paper, the theoretical considerations and experimental verifications of this contact pulse-echo low-liquid- level sensor (LI.,S) are reviewed. In addition, various analytical methods are used to study the failed interface between the piezoelectric element and the acoustic matching plate. 43366 Tittmann, B.R.: Linebarger, R.S.; Addison, R.C. L a s e r - b a s e d ultrasonics on G r / E p o x y composite - a systems analysis Review of Progress in Quantitative Nondestructive Evaluation, Vol. 8A. Edited by D.C. Thompson and D.E. Chimenti, pp. 513-520. Plenum Press (1989), ISBN 0 306 43209 9 Critical issues are examined in the application of laser generation and detection of ultrasound to the inspection of large area air-frame composites. Among these issues are surface roughness, signal-to-noise ratio, insensitivity to the path length between the part and detector, and wide-band versus narrow-band generation. Supporting experiments are reported on broad-band and narrow-band generation in Gr/Epoxy panels and angular reflectance measurements on painted and unpainted Gr/Epoxy. On the basis of these measurements, a laser-in/laser-out systems analysis is carried out for a 10 mm diameter delamination about I cm deep. 43182 Walkden, P. A u t o m a t e d u l t r a s o n i c defect d i s c r i m i n a t i o n Materials Evaluation, Voi. 47, No. 9, pp. 1000-1004 (Sep. 1989) Today fibre-reinforced composite materials, widely used in military and civilian aircraft, have such complicated internal structures that successful nondestructive testing can be problematic, both during and after fabrication. However. advances in ultrasonic testing have led to the development of automated on-line systems with digital processing and display of results. These devices can perform inspections repeatedly and reliably and reveal the composite materials' complex macro-and microscopic structures. One such system, developed by Rolls- Royce Mateval Ltd. is described, which even highlights potential defects automatically for the operator's attention.
43179 Rangachary, T.; Ganesha, H.S. Ultrasonic testing in a e r o n a u t i c s i n d u s t r y Proceedings of the National Symposium on Acoustics, Tiruchirapalli, (India), 27-30 Dec. 1987. pp. 193-198 Acoustical Society of India The wide range of applications for ultrasonic (US) testing in the aeronautics industry is the subject of this paper. Component specifications must, of necessity, be rigorous and US testing have a role to play in selection of materials testing of semifinisbed products, monitoring structural integrity inservice, failure investigation and testing of bond quality. The author discusses each of tbese areas and offer ideas about how the technique can be adapted to each circumstance. 43174
Tow, D.M.; Barna, B.A.; Rodriguez, J.G.
NDE ( n o n d e s t r u c t i v e evaluation) of the space shuttle o r b i t e r t h e r m a l protection system: phase 2 final r e p o r t EG and G Idaho, Inc., Idaho Falls, (United States), DE89010975/GAR, 54pp. (Mar. 1989) Research continued on the development of a nondestructive evaluation technique for inspecting bonds on the space shuttle orbiter thermal protection system tiles. The approach taken uses a noncontacting laser sensor to measure the vibrational response of bonded tiles to acoustical excitation. Laboratory work concentrated on investigating the dynamic response of "acreage" tiles, i.e., tiles covering the underside of the orbiter, all approximately square. A number of promising unbond signatures have been identified in the time and frequency domain response. Field tests were conducted to study environmental effects on the techniques being developed. The ambient motion of the orbiter was found to be larger than expected, necessitating modifications to current techniques. 43146 Fuller, M.D. Ultrasonic evaluation of m a t r i x c r a c k i n g in g r a p h i t e B M I Composite Applications, The Future is Now. Edited by T.J. Drozda. pp. 314-326 Society of Manufacturing Engineers, 466pp. (1990) ISBN 0872633551 Martin Marietta exploits the advantages of advanced composite materials in the design and manufacture of jet engine fan reversers. One of several fan reverser structures which are fabricated with composite materials is the pre-cooler duel The precooler duct is constructed of graphite and Nextel fibers using a Bismaliimide (BMIi) matrix. The BMi resin system used in the hardware was dictated by high service temperature specifications. The processing plan calls for a postcure at 450F, this temperature coupled with the complex geometry and, the specific resin system produces cracking in the radii sections of the finished hardware. Engineering analysis and testing was conducted to demonstrate that the design was tolerant to this defecL at the level of severity it was expected to occur. 42658 Smith, A.C.; Yang, H. Ultrasonic s t u d y of adhesive b o n d quality a t a s t e e l - t o - r u b b e r interface by using q u a d r a t u r e p h a s e detection t e c h n i q u e s Materials Evaluation, Vol. 47, No. 12, pp. 1396-1400 (Dec. 1989) The quadrature phase detection technique was used to simultaneously monitor the phase and amplitude of a toneburst signal normally reflected from an adhesively bonded steel-to-rubber interface. The measured phase was found to show a positive shift for all bonded samples with respect to the disbonded state-the phase shift being larger for samples with weaker bonds, as manifested by smaller values of applied tensile loads at failure. A model calculation, which incorporates the concept of interracial strength into the usual problem of wave propagation in multilayered media, was used to deduce a bond- quality parameter from an experimentally measured phase shift. This bond-quality parameter was found to be correlated with the tensile strength of the adhesive bonds at failure loads.
Shimizu, M.; ltoh, K.; Fujiwara, T.; Fukushima, Y.; Takahashi, M.; Maniwa, T.
42645
Swept frequency type of u l t r a s o n i c inspection m e t h o d for linear- p r o p e l l a n t s e p a r a t i o n s of the H-I u p p e r - s t a g e m o t o r s Journal Spacecraft, Vol. 26, No. 5, pp. 379-384 This paper describes the swept frequency type of ultrasonic inspection method that is usable for inspecting not only case-liner separations, but liner-propellant separations of solid motors and successful application of the method to the H-I upper-stage motors. The new method has been developed at the National Aerospace Laboratory (NAL) since 1968, and the inspection technique is based on the one-dimensional quarter-wavelength resonance principle for the liner thickness under one free and the other fixed end-face boundary condition, which is considered the liner-propellant separation boundary condition of the liner. Since the motor cases have curved (spherical or cylindrical) surfaces, some curved contact surface probes were developed.
NDT&E
I n t e r n a t i o n a l 1 9 9 4 V o l u m e 27, N u m b e r 3
163
NDE in resin matrix composites was investigated. In the case of neat resins it was found that. at normal incidence, about 25 percent of the laser pulse energy is reflected at the incident surface, it was found in energy balance studies that graphite fiber/polymer specimens attenuate the laser beam more than do the neat resins. The increased absorption is in the graphite fibers. The occurrence of laser induced surface damage was also studied. The damage threshold is between 0.06 and 0.07 J/cm. 43421 Hemann, J.H.; Cavano, P.; Kautz, H.; Bowles, K. T r a n s - p l y c r a c k density detection by acouste~-ultrasonics Acousto - Ultrasonics, Theory and Application. Edited by J.C. Duke, Jr., pp. 319-325, Plenum Press, 353pp. (1989). ISBN 0306430134 This paper describes how acousto-ultrasonics can be used to detect trans-ply cracks in graphitedPMR polyimide cruss-ply and woven fabric laminates, which are used in high temperature zones in jet engines. Trans-ply cracks seriously reduce the mechanical strength of the structure. It is shown that the acousto-ultrasonic stress wave factor (SWF) correlates with trans-ply crack density where cracks are created by tensile loading of the material. The SWF is shown to be a practical measure and predictor of crack density in laminated composite materials. 43411
Odell, J.H.
NDT of the c a r b o n fibre composite s t r u c t u r e of the H a r r i e r GR5 in service Reliability in Non-Destructive Testing, Proceedings of the 27th Annual British Conference on Non-Destructive Testing, Portsmouth (United Kingdom), 12-15 Sep. 1988. pp. 249-259. Edited by C. Brook and P.D. Hanstead. Pergamon Press, 1989. The RAF now faces the problems of operating aircraft with major components of Carbon Fibre Composite (CFC) in particular the Harrier OR5. Likely forms of damage which may occur in service have been identified, and a joint trial with RAE Farnborough has beencarried out on a representative CFC structure. Appropriate methods of Non Destructive Testing (NDT) have been identified and trials have been carried out on candidate NDT equipments. Service experience of NDT related problems with Harrier CFC structure indicates the minimal additional equipment will be required to meet our needs. 43392 Chern, EJ.: Djordjevic, B.B. N o n i n t r u s i v e u l t r a s o n i c low-liquid-level sensor Materials Evaluation, Vol. 48, No. 4, pp. 481-485 (Apr. 1990) A nonintrusive ultrasonic sensor system for monitoring the fuel level in the liquid propellant tanks of space launch vehicles has been developed and tested, in this paper, the theoretical considerations and experimental verifications of this contact pulse-echo low-liquid- level sensor (LI.,S) are reviewed. In addition, various analytical methods are used to study the failed interface between the piezoelectric element and the acoustic matching plate. 43366 Tittmann, B.R.: Linebarger, R.S.; Addison, R.C. L a s e r - b a s e d ultrasonics on G r / E p o x y composite - a systems analysis Review of Progress in Quantitative Nondestructive Evaluation, Vol. 8A. Edited by D.C. Thompson and D.E. Chimenti, pp. 513-520. Plenum Press (1989), ISBN 0 306 43209 9 Critical issues are examined in the application of laser generation and detection of ultrasound to the inspection of large area air-frame composites. Among these issues are surface roughness, signal-to-noise ratio, insensitivity to the path length between the part and detector, and wide-band versus narrow-band generation. Supporting experiments are reported on broad-band and narrow-band generation in Gr/Epoxy panels and angular reflectance measurements on painted and unpainted Gr/Epoxy. On the basis of these measurements, a laser-in/laser-out systems analysis is carried out for a 10 mm diameter delamination about I cm deep. 43182 Walkden, P. A u t o m a t e d u l t r a s o n i c defect d i s c r i m i n a t i o n Materials Evaluation, Voi. 47, No. 9, pp. 1000-1004 (Sep. 1989) Today fibre-reinforced composite materials, widely used in military and civilian aircraft, have such complicated internal structures that successful nondestructive testing can be problematic, both during and after fabrication. However. advances in ultrasonic testing have led to the development of automated on-line systems with digital processing and display of results. These devices can perform inspections repeatedly and reliably and reveal the composite materials' complex macro-and microscopic structures. One such system, developed by Rolls- Royce Mateval Ltd. is described, which even highlights potential defects automatically for the operator's attention.
43179 Rangachary, T.; Ganesha, H.S. Ultrasonic testing in a e r o n a u t i c s i n d u s t r y Proceedings of the National Symposium on Acoustics, Tiruchirapalli, (India), 27-30 Dec. 1987. pp. 193-198 Acoustical Society of India The wide range of applications for ultrasonic (US) testing in the aeronautics industry is the subject of this paper. Component specifications must, of necessity, be rigorous and US testing have a role to play in selection of materials testing of semifinisbed products, monitoring structural integrity inservice, failure investigation and testing of bond quality. The author discusses each of tbese areas and offer ideas about how the technique can be adapted to each circumstance. 43174
Tow, D.M.; Barna, B.A.; Rodriguez, J.G.
NDE ( n o n d e s t r u c t i v e evaluation) of the space shuttle o r b i t e r t h e r m a l protection system: phase 2 final r e p o r t EG and G Idaho, Inc., Idaho Falls, (United States), DE89010975/GAR, 54pp. (Mar. 1989) Research continued on the development of a nondestructive evaluation technique for inspecting bonds on the space shuttle orbiter thermal protection system tiles. The approach taken uses a noncontacting laser sensor to measure the vibrational response of bonded tiles to acoustical excitation. Laboratory work concentrated on investigating the dynamic response of "acreage" tiles, i.e., tiles covering the underside of the orbiter, all approximately square. A number of promising unbond signatures have been identified in the time and frequency domain response. Field tests were conducted to study environmental effects on the techniques being developed. The ambient motion of the orbiter was found to be larger than expected, necessitating modifications to current techniques. 43146 Fuller, M.D. Ultrasonic evaluation of m a t r i x c r a c k i n g in g r a p h i t e B M I Composite Applications, The Future is Now. Edited by T.J. Drozda. pp. 314-326 Society of Manufacturing Engineers, 466pp. (1990) ISBN 0872633551 Martin Marietta exploits the advantages of advanced composite materials in the design and manufacture of jet engine fan reversers. One of several fan reverser structures which are fabricated with composite materials is the pre-cooler duel The precooler duct is constructed of graphite and Nextel fibers using a Bismaliimide (BMIi) matrix. The BMi resin system used in the hardware was dictated by high service temperature specifications. The processing plan calls for a postcure at 450F, this temperature coupled with the complex geometry and, the specific resin system produces cracking in the radii sections of the finished hardware. Engineering analysis and testing was conducted to demonstrate that the design was tolerant to this defecL at the level of severity it was expected to occur. 42658 Smith, A.C.; Yang, H. Ultrasonic s t u d y of adhesive b o n d quality a t a s t e e l - t o - r u b b e r interface by using q u a d r a t u r e p h a s e detection t e c h n i q u e s Materials Evaluation, Vol. 47, No. 12, pp. 1396-1400 (Dec. 1989) The quadrature phase detection technique was used to simultaneously monitor the phase and amplitude of a toneburst signal normally reflected from an adhesively bonded steel-to-rubber interface. The measured phase was found to show a positive shift for all bonded samples with respect to the disbonded state-the phase shift being larger for samples with weaker bonds, as manifested by smaller values of applied tensile loads at failure. A model calculation, which incorporates the concept of interracial strength into the usual problem of wave propagation in multilayered media, was used to deduce a bond- quality parameter from an experimentally measured phase shift. This bond-quality parameter was found to be correlated with the tensile strength of the adhesive bonds at failure loads.
Shimizu, M.; ltoh, K.; Fujiwara, T.; Fukushima, Y.; Takahashi, M.; Maniwa, T.
42645
Swept frequency type of u l t r a s o n i c inspection m e t h o d for linear- p r o p e l l a n t s e p a r a t i o n s of the H-I u p p e r - s t a g e m o t o r s Journal Spacecraft, Vol. 26, No. 5, pp. 379-384 This paper describes the swept frequency type of ultrasonic inspection method that is usable for inspecting not only case-liner separations, but liner-propellant separations of solid motors and successful application of the method to the H-I upper-stage motors. The new method has been developed at the National Aerospace Laboratory (NAL) since 1968, and the inspection technique is based on the one-dimensional quarter-wavelength resonance principle for the liner thickness under one free and the other fixed end-face boundary condition, which is considered the liner-propellant separation boundary condition of the liner. Since the motor cases have curved (spherical or cylindrical) surfaces, some curved contact surface probes were developed.
NDT&E
I n t e r n a t i o n a l 1 9 9 4 V o l u m e 27, N u m b e r 3
163