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  • Weitere Quellen  (20)
  • COMPOSITE MATERIALS  (14)
  • AEROSPACE MEDICINE  (6)
  • Humans
  • Lepidoptera
  • 2000-2004
  • 1990-1994  (13)
  • 1980-1984  (7)
  • 1
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    Mechanical property characterization and impact resistance of selected graphite/PEEK composite materials (1994)
    In:  Other Sources
    Details
    Publikationsdatum: 2011-08-24
    Beschreibung: To use graphite polyetheretherketone (PEEK) material on highly curved surfaces requires that the material be drapable and easily conformable to the surface. This paper presents the mechanical property characterization and impact resistance results for laminates made from two types of graphite/PEEK materials that will conform to a curved surface. These laminates were made from two different material forms. These forms are: (1) a fabric where each yarn is a co-mingled Celion G30-500 3K graphite fiber and PEEK thermoplastic fiber; and (2) an interleaved material of Celion G30-500 3K graphite fabric interleaved with PEEK thermoplastic film. The experimental results from the fabric laminates are compared with results for laminates made from AS4/PEEK unidirectional tape. The results indicate that the tension and compression moduli for quasi-isotropic and orthotropic laminates made from fabric materials are at least 79 percent of the modulus of equivalent laminates made from tape material. The strength of fabric material laminates is at least 80 percent of laminates made from tape material. The evaluation of fabric material for shear stiffness indicates that a tape material laminate could be replaced by a fabric material laminate and still maintain 89 percent of the shear stiffness of the tape material laminate. The notched quasi-isotropic compression panel failure strength is 42 to 46 percent of the unnotched quasi-isotropic laminate strength. Damage area after impact with 20 ft-lbs of impact energy is larger for the co-mingled panels than for the interleaved panels. The inerleaved panels have less damage than panels made from tape material. Residual compression strength of quasi-isotropic panels after impact of 20 ft-lbs of energy varies between 33 percent of the undamaged quasi-isotropic material strength for the tape material and 38 percent of the undamaged quasi-isotropic material strength for the co-mingled fabric material.
    Schlagwort(e): COMPOSITE MATERIALS
    Materialart: Journal of the American Helicopter Society (ISSN 0002-8711); 39; 1; p. 24-30
    Format: text
    Standort Signatur Erwartet Verfügbarkeit
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    NASA TECHNICAL REPORTS
  • 2
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    The adaptation of vestibulo-spinal reflexes as a function of spaceflight and their relationship to space motion sickness (1984)
    In:  CASI
    Details
    Publikationsdatum: 2006-02-14
    Beschreibung: The hypothesis that exposure to prolonged free fall is a form of sensorymotor rearrangement rather than a direct change in otolith sensitivity or sensory compensation for a reduced otolith input is discussed. Data from Spacelab-1 experiment 1NS-104 are presented to support an otolith reinterpretation hypothesis. This experiment measured vestibulo-spinal reflex changes as a function of sustained free fall. Findings indicate that when a monosynaptic reflex (H-reflex), measured from the major postural muscles (soleus) is used, adaptation to space flight includes a change in how the central nervous system interprets a fall. In a normal gravity environment a sudden unexpected fall produces a potentiated H-reflex. After 7 days inflight, an equivalent fall does not potentiate the reflex. Postflight a greatly increased reflex is observed in those crewmen most susceptible to space motion sickness.
    Schlagwort(e): AEROSPACE MEDICINE
    Materialart: ESA Life Sci. Res. in Space; p 237-245
    Format: text
    Standort Signatur Erwartet Verfügbarkeit
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    NASA TECHNICAL REPORTS
  • 3
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    Acoustically based fetal heart rate monitor (1991)
    In:  CASI
    Details
    Publikationsdatum: 2013-08-31
    Beschreibung: The acoustically based fetal heart rate monitor permits an expectant mother to perform the fetal Non-Stress Test in her home. The potential market would include the one million U.S. pregnancies per year requiring this type of prenatal surveillance. The monitor uses polyvinylidene fluoride (PVF2) piezoelectric polymer film for the acoustic sensors, which are mounted in a seven-element array on a cummerbund. Evaluation of the sensor ouput signals utilizes a digital signal processor, which performs a linear prediction routine in real time. Clinical tests reveal that the acoustically based monitor provides Non-Stress Test records which are comparable to those obtained with a commercial ultrasonic transducer.
    Schlagwort(e): AEROSPACE MEDICINE
    Materialart: NASA, Washington, Technology 2001: The Second National Technology Transfer Conference and Exposition, Volume 2; p 512-517
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 4
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    Evaluation of composite components on the Bell 206L and Sikorsky S-76 helicopters (1990)
    In:  CASI
    Details
    Publikationsdatum: 2013-08-29
    Beschreibung: Progress on two programs to evaluate structural composite components in flight service on Bell 206L and Sikorsky S-76 commercial helicopters is described. Forty ship sets of composite components that include the litter door, baggage door, forward fairing, and vertical fin have been installed on Bell Model 206L helicopters that are operating in widely different climates. Component installation started in 1981 and selected components were removed and tested at prescribed intervals over a ten year evaluation. Four horizontal stabilizers and eleven tail rotor spars that are production components on the S-76 helicopter were tested after prescribed periods of service to determine the effects of the operating environment on their performance. Concurrent with the flight evaluation, materials used to fabricate the components were exposed in ground racks and tested at specified intervals to determine the effects of outdoor environments. Results achieved from 123,000 hours of accumulated service on the Bell 206L components and 53,000 hours on the Sikorsky S-76 components are reported. Seventy-eight Bell 206L components were removed and tested statically. Results of seven years of ground exposure of materials used to fabricate the Bell 206L components are presented. Results of tests on four Sikorsky S-76 horizontal stabilizers and eleven tail rotor spars are also presented. Panels of material used to fabricate the Sikorsky S-76 components that were exposed for six years were tested and results are presented.
    Schlagwort(e): COMPOSITE MATERIALS
    Materialart: NASA. Langley Research Center, Eighth DOD(NASA)FAA Conference on Fibrous Composites in Structural Design, Part 2; p 393-428
    Format: text
    Standort Signatur Erwartet Verfügbarkeit
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  • 5
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    Ground exposure of composite materials for helicopters (1984)
    In:  Other Sources
    Details
    Publikationsdatum: 2011-08-19
    Beschreibung: Residual strength results are presented on four composite material systems that were exposed for three years at locations on the North American Continent. The exposure locations are near the areas where Bell Model 206L Helicopters, that are in a NSA/U.S. Army sponsored flight service program, are flying in daily commercial service. The composite systems are: (1) Kevlar-49 fabric/F-185 epoxy; (2) Kevlar-49 fabric/LRF-277 epoxy; (3) Kevlar-49 fabric/CE-306 epoxy; and (4) T-300 Graphite/E-788 epoxy. All material systems exhibited good strength retention in compression and short beam shear. The Kevlar-49/LRF-277 epoxy retained 88 to 93 percent of the baseline strength while the other material systems exceeded 95 percent of baseline strength. Residual tensile strength of all materials did not show a significant reduction. The available moisture absorption data is also presented.
    Schlagwort(e): COMPOSITE MATERIALS
    Format: text
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  • 6
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    Worldwide flight and ground-based exposure of composite materials (1984)
    In:  CASI
    Details
    Publikationsdatum: 2016-06-07
    Beschreibung: The long-term durability of those advanced composite materials which are applicable to aircraft structures was discussed. The composite components of various military and commercial aircraft and helicopters were reviewed. Both ground exposure and flight service were assessed in terms of their impact upon composite structure durability. The ACEE Program is mentioned briefly.
    Schlagwort(e): COMPOSITE MATERIALS
    Materialart: ACEE Composite Struct. Technol.; p 17-50
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 7
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    Flight service environmental effects on composite materials and structures (1992)
    In:  CASI
    Details
    Publikationsdatum: 2017-10-02
    Beschreibung: NASA Langley and the U.S. Army have jointly sponsored programs to assess the effects of realistic flight environments and ground-based exposure on advanced composite materials and structures. Composite secondary structural components were initially installed on commercial transport aircraft in 1973; secondary and primary structural components were installed on commercial helicopters in 1979; and primary structural components were installed on commercial aircraft in the mid-to-late 1980's. Service performance, maintenance characteristics, and residual strength of numerous components are reported. In addition to data on flight components, 10 year ground exposure test results on material coupons are reported. Comparison between ground and flight environmental effects for several composite material systems are also presented. Test results indicate excellent in-service performance with the composite components during the 15 year period. Good correlation between ground-based material performance and operational structural performance has been achieved.
    Schlagwort(e): COMPOSITE MATERIALS
    Materialart: AGARD, The Utilization of Advanced Composites in Military Aircraft; 13 p
    Format: text
    Standort Signatur Erwartet Verfügbarkeit
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    NASA TECHNICAL REPORTS
  • 8
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    X ray imaging microscope for cancer research (1991)
    In:  CASI
    Details
    Publikationsdatum: 2019-06-28
    Beschreibung: The NASA technology employed during the Stanford MSFC LLNL Rocket X Ray Spectroheliograph flight established that doubly reflecting, normal incidence multilayer optics can be designed, fabricated, and used for high resolution x ray imaging of the Sun. Technology developed as part of the MSFC X Ray Microscope program, showed that high quality, high resolution multilayer x ray imaging microscopes are feasible. Using technology developed at Stanford University and at the DOE Lawrence Livermore National Laboratory (LLNL), Troy W. Barbee, Jr. has fabricated multilayer coatings with near theoretical reflectivities and perfect bandpass matching for a new rocket borne solar observatory, the Multi-Spectral Solar Telescope Array (MSSTA). Advanced Flow Polishing has provided multilayer mirror substrates with sub-angstrom (rms) smoothnesss for the astronomical x ray telescopes and x ray microscopes. The combination of these important technological advancements has paved the way for the development of a Water Window Imaging X Ray Microscope for cancer research.
    Schlagwort(e): AEROSPACE MEDICINE
    Materialart: National Aeronautics and Space Administration, Technology 2000, Volume 1; p 73-82
    Format: application/pdf
    Standort Signatur Erwartet Verfügbarkeit
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  • 9
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    Ten-year ground exposure of composite materials used on the Bell Model 206L helicopter flight service program (1994)
    In:  CASI
    Details
    Publikationsdatum: 2019-06-28
    Beschreibung: Residual strength results are presented for four composite material systems that have been exposed for up to 10 years to the environment at five different locations on the North American continent. The exposure locations are near where the Bell Model 206L helicopters, which participated in a flight service program sponsored by NASA Langley Research Center and the U.S. Army, were flying in daily commercial service. The composite material systems are (1) Kevlar-49 fabric/F-185 epoxy; (2) Kevlar-49 fabric/LRF-277 epoxy; (3) Kevlar-49 fabric/CE-306 epoxy; and (4) T-300 graphite/E-788 epoxy. Six replicates of each material were removed and tested after 1, 3, 5, 7, and 10 years of exposure. The average baseline strength was determined from testing six as-fabricated specimens. More than 1700 specimens have been tested. All specimens that were tested to determine their strength were painted with a polyurethane paint. Each set of specimens also included an unpainted panel for observing the weathering effects on the composite materials. A statistically based procedure has been used to determine the strength value above which at least 90 percent of the population is expected to fall with a 95-percent confidence level. The computed compression strengths are 80 to 90 percent of the baseline (no-exposure) strengths. The resulting compression strengths are approximately 8 percent below the population mean strengths. The computed short-beam-shear strengths are 83 to 92 percent of the baseline (no-exposure) strengths. The computed tension strength of all materials is 93 to 97 percent of the baseline (no-exposure) strengths.
    Schlagwort(e): COMPOSITE MATERIALS
    Materialart: NASA-TP-3468 , L-17341 , ARL-TR-480 , NAS 1.60:3468
    Format: application/pdf
    Standort Signatur Erwartet Verfügbarkeit
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  • 10
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    Fatigue characterization of advanced carbon-carbon composites (1992)
    In:  Other Sources
    Details
    Publikationsdatum: 2019-06-28
    Beschreibung: Response of quasi-isotropic laminates of SiC coated Carbon-Carbon (C/C) composites under flexural fatigue are investigated at room temperature. Virgin as well as mission cycled specimens are tested to study the effects of thermal and pressure cycling on the fatigue performance of C/C. Tests were conducted in three point bending with a stress ratio of 0.2 and frequency of 1 Hz. Fatigue strength of C/C has been found to be considerably high - approximately above 85 percent of the ultimate flexural strength. The fatigue strength appears to be decreasing with the increase in the number of mission cycling of the specimens. This lower strength with the mission cycled specimens is attributed to the loss of interfacial bond strength due to thermal and pressure cycling of the material. C/C is also found to be highly sensitive to the applied stress level during cyclic loading, and this sensitivity is observed to increase with the mission cycling. Weibull characterization on the fatigue data has been performed, and the wide scatter in the Weibull distribution is discussed. Fractured as well as untested specimens were C-scanned, and the progressive damage growth during fatigue is presented.
    Schlagwort(e): COMPOSITE MATERIALS
    Materialart: In: International Congress on Experimental Mechanics, 7th, Las Vegas, NV, June 8-11, 1992, Proceedings. Vol. 2 (A94-12901 02-39); p. 1368-1373.
    Format: text
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