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  • SPACE RADIATION  (6)
  • COMPOSITE MATERIALS  (4)
  • 2020-2021
  • 1985-1989  (7)
  • 1980-1984  (3)
  • 1
    Publication Date: 2016-06-07
    Description: Following from early experience with polyimides on the SST program and Shuttle aft flap studies the Boeing Company is now working on collaborative programs with its principal nacelle suppliers to pursue the development of Gr/PMR-15 nacelle components. Two programs are currently in effect. The first program is directed specifically towards the flight test and service evaluation at the earliest possible date of a 747 nacelle core cowl structure. The second program seeks to firmly establish the producibility and cost of a 757 thrust reverser C duct in a production environment. The near term objectives of these programs include: (1) the comparison of estimated cost and weight of Gr/PMR-15 versus metal structure, (2) the engine test of representative composite structure, (3) the preliminary design and analysis of the C duct structure, and (4) the preparation of cost data and time schedules for the development and producibility program. In addition to powerplant structure, the propulsion ducting system has shown to be a strong candidate for Gr/PMR-15 application. Currently, the Boeing 747 Organization is evaluating the use of PMR-15 matrix composites to replace nearly 800 lbs of titanium ducting per airplane.
    Keywords: COMPOSITE MATERIALS
    Type: NASA. Lewis Research Center High Temp. Polymer Matrix Composites; p 393-400
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  • 2
    Publication Date: 2019-06-28
    Description: Data for evaluating the effects of moisture and temperature on the integrity of fiber composite components was gathered. In particular, the static and cyclic performance of three composite laminates containing flaws was investigated at room temperature and at 422 K (300 F) in wet and dry conditions.
    Keywords: COMPOSITE MATERIALS
    Type: NASA-CR-165213 , NAS 1.26:165213
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  • 3
    Publication Date: 2019-06-28
    Description: Turver and Weekes proposed using a system of phototubes in the focal plane of a large reflector to give an air Cherenkov camera for gamma ray astronomy. Preliminary results with a 19 element camera have been reported previously. In 1983 the camera was increased to 37 pixels; it has now been routinely operated for two years. A brief physical description of the camera, its mode of operation, and the data reduction procedures are presented. The Monte Carlo simultations on which these are based on also reviewed.
    Keywords: SPACE RADIATION
    Type: OG-9.5-4 , 19th Intern. Cosmic Ray Conf - Vol. 3; p 453-456; NASA-CP-2376-VOL-3
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  • 4
    Publication Date: 2019-06-28
    Description: The 1.24 second binary pulsar Her X-1, first observed in X-rays in 1971 by UHURU has now been seen as a sporadic gamma ray source from 1 TeV up to at least 500 TeV. In addition, reprocessed optical and infrared pulses are seen from the companion star HZ Herculis. Thus measurements of the Her X-1/HZ Herculis system span 15 decades in energy, rivaling both the Crab pulsar and Cygnus X-3 in this respect for a discrete galactic source.
    Keywords: SPACE RADIATION
    Type: OG-2.2-9 , 19th Intern. Cosmic Ray Conf - Vol. 1; p 119-122; NASA-CP-2376-VOL-1
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  • 5
    Publication Date: 2019-06-28
    Description: Cygnus X-3 is observed to emit gamma rays with energies in excess of 4 x 10 to the 11th power eV during two out of 9 observational categories over an 18 month time span. The emissions are observed at the 0.6 phase of the characteristic 4.8 hr light curve for this binary system. We estimate a peak flux at phase 0.6 of 5 x 10 to the minus 10th power photons cm-2s-1 at a software threshold of 8 x 10 to the 11th power eV for Oct/Nov 1983. A flux for the June 84 effect cannot be reliably calculated at present due to lack of Monte Carlo simulations for the energy range and spectral region. For the other 7 observational categories the observations are consistent with zero source emission. The light curve would appear to be variable on a time scale of a couple of weeks at these categories. Selection of compact images in accordance with Monte Carlo simulations combined with empirical optimization techniques have led to an enriched gamma ray light curve for the Oct/Nov 1983 data. Selection on the basis of shower orientation, however, has not led to any notable enhancement of the gamma ray content. Individual Cherenko images can be reliably sorted on an event by event basis into either proton-induced or photon-induced showers.
    Keywords: SPACE RADIATION
    Type: OG-2.1-11 , 19th Intern. Cosmic Ray Conf - Vol. 1; p 87-90; NASA-CP-2376-VOL-1
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  • 6
    Publication Date: 2019-06-28
    Description: Although the existence of fluxes of gamma-rays of energies 10 to the 12th power eV is now established for galactic sources, the detection of such gamma-rays from extragalactic sources has yet to be independently confirmed in any case. The detection and confirmation of such energetic photons is of great astrophysical importance in the study of production mechanisms for cosmic rays, and other high energy processes in extragalactic objects. Observations of m31 are discussed. It is reported as a 10 to the 12th power eV gamma-ray source. Flux limits on a number of other extragalactic objects chosen for study are given.
    Keywords: SPACE RADIATION
    Type: OG-2.7-3 , 19th Intern. Cosmic Ray Conf - Vol. 1; p 264-267; NASA-CP-2376-VOL-1
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  • 7
    Publication Date: 2019-06-28
    Description: Observations of Geminga made at the Whipple Observatory using the atmospheric Cherenkov technique during the moonless periods of November 1983 to February 1984 and November 1984 till February 1985 were examined for evidence for the emission of gamma rays with energy in excess of approx 400 GeV. Evidence of either a steady flux or a flux pulsed with a period near 60 seconds were studied. In neither case was any significant effect observed, enabling the establishment 3 of sigma upper limits of 5.5 x 10 to the -11th power photons/sq cm/s and 2.0 x 10 to the -11th power photons/sq cm/s for the steady and pulsed emission respectively. The limit to the pulsed flux is approximately a factor of six below that predicted.
    Keywords: SPACE RADIATION
    Type: OG-2.4-4 , 19th Intern. Cosmic Ray Conf - Vol. 1; p 173-176; NASA-CP-2376-VOL-1
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  • 8
    Publication Date: 2019-06-28
    Description: Since the development of gamma-ray astronomical telescopes, the Crab Nebula has been a prime target for observations. From 100 to 1000 MeV, the pulsar PSR0531 is the dominant source with a light-curve similar to that seen at lower energies; there is also some evidence for longterm amplitude variations but none for emission from the Nebula itself. In the very high energy gamma-ray region there have been reported detections of pulsed emission with longterm time variations from minutes to months. Recently a pulsed flux has been reported that resisted over a long time interval. The detection of a flux from the Nebula at the 3 sigma level at energies of 3x1011eV was reported; there was no evidence of periodic emissions on any time scale during the three years of observations. A new measurement of very high energy gamma rays from the Crab Nebula is reported using the imaging system on the Whipple Observatory 10m reflector.
    Keywords: SPACE RADIATION
    Type: OG-2.3-1 , 19th Intern. Cosmic Ray Conf - Vol. 1; p 131-134; NASA-CP-2376-VOL-1
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  • 9
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    In:  Other Sources
    Publication Date: 2019-07-13
    Description: An experimental program was carried out to investigate the effects of temperature and moisture on the damage development and fracture response of graphite/epoxy composites. Fracture response data were obtained for 20-ply laminates of different layup patterns for both room temperature and immediately after the application of a temperature transient causing the specimen to attain 150 C. It is found that elevated temperature degrades the notched strength of some laminates while not degrading others. The unnotched strength of all laminates tested at elevated temperatures was degraded. The effect of preloading on damage growth and moisture absorption, the effect of autoclave pressure during the laminate cure on fracture, and the variation of interlaminar shear properties with layup, moisture exposure, laminate material, and cure pressure are also discussed.
    Keywords: COMPOSITE MATERIALS
    Type: Symposium on Test methods and design allowables for fibrous composites; Oct 02, 1979 - Oct 03, 1979; Dearborn, MI
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  • 10
    Publication Date: 2019-07-13
    Description: The effects of moisture and temperature on the fatigue and fracture response of composite laminates under compression loads were investigated. The structural laminates studied were an intermediate stiffness graphite-epoxy composite (a typical angle ply laimna liminate had a typical fan blade laminate). Full and half penetration slits and impact delaminations were the defects examined. Results are presented which show the effects of moisture on the fracture and fatigue strength at room temperature, 394 K (250 F), and 422 K (300 F). Static tests results show the effects of defect size and type on the compression-fracture strength under moisture and thermal environments. The cyclic tests results compare the fatigue lives and residual compression strength under compression only and under tension-compression fatigue loading.
    Keywords: COMPOSITE MATERIALS
    Type: NASA-CR-168023 , NAS 1.26:168023 , D180-27619-1
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