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  • 1
    facet.materialart.
    Unknown
    Mechanical property characterization and impact resistance of selected graphite/PEEK composite materials (1994)
    In:  Other Sources
    Details
    Publication Date: 2011-08-24
    Description: 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.
    Keywords: COMPOSITE MATERIALS
    Type: Journal of the American Helicopter Society (ISSN 0002-8711); 39; 1; p. 24-30
    Format: text
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    NASA TECHNICAL REPORTS
  • 2
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    Evaluation of composite components on the Bell 206L and Sikorsky S-76 helicopters (1990)
    In:  CASI
    Details
    Publication Date: 2013-08-29
    Description: 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.
    Keywords: COMPOSITE MATERIALS
    Type: NASA. Langley Research Center, Eighth DOD(NASA)FAA Conference on Fibrous Composites in Structural Design, Part 2; p 393-428
    Format: text
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  • 3
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    Ground exposure of composite materials for helicopters (1984)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: 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.
    Keywords: COMPOSITE MATERIALS
    Format: text
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  • 4
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    Unknown
    Worldwide flight and ground-based exposure of composite materials (1984)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: 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.
    Keywords: COMPOSITE MATERIALS
    Type: ACEE Composite Struct. Technol.; p 17-50
    Format: application/pdf
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  • 5
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    Flight service environmental effects on composite materials and structures (1992)
    In:  CASI
    Details
    Publication Date: 2017-10-02
    Description: 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.
    Keywords: COMPOSITE MATERIALS
    Type: AGARD, The Utilization of Advanced Composites in Military Aircraft; 13 p
    Format: text
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  • 6
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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
    Publication Date: 2019-06-28
    Description: 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.
    Keywords: COMPOSITE MATERIALS
    Type: NASA-TP-3468 , L-17341 , ARL-TR-480 , NAS 1.60:3468
    Format: application/pdf
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  • 7
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    Fatigue characterization of advanced carbon-carbon composites (1992)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: 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.
    Keywords: COMPOSITE MATERIALS
    Type: 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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  • 8
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    Unknown
    Five year ground exposure of composite materials used on the Bell Model 206L flight service evaluation (1989)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Part of the results of a U.S. Army/NASA-Langley sponsored research program to establish the long term-term effects of realistic ground based exposure on advanced composite materials is presented. Residual strengths and moisture absorption as a function of exposure time and exposure location are reported for four different composite material systems that were exposed for five years on the North American Continent.
    Keywords: COMPOSITE MATERIALS
    Type: NASA-TM-101645 , NAS 1.15:101645 , AVSCOM-TM-89-B-007 , AD-A233549
    Format: application/pdf
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  • 9
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    Unknown
    Flight service evaluation of composite components on Bell 206L and Sikorsky S-76 helicopters (1983)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Progress on two programs to evaluate composite structural components in flight service on commercial helicopters is described. Thirty-six ship sets of composite components that include the litter door, baggage door, forward fairing, and vertical fin were installed on Bell Model 206L helicopters that are operating in widely different climatic areas. Four horizontal stabilizers and ten 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, specimens from 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 14,000 hours of accumulated service on the 206L components, tests on a S-76 horizontal stabilizer after 1600 hours of service, tests on a S-76 tail rotor spar after 2300 hours service, and two years of ground based exposure of material coupons are reported.
    Keywords: COMPOSITE MATERIALS
    Type: NASA-TM-84637 , NAS 1.15:84637 , AVRADCOM-TR-83-B-1 , AHS Natl. Specialist''s Meeting: Composite Structures; Mar 23, 1983 - Mar 25, 1983; Philadelphia
    Format: application/pdf
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  • 10
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    Stress analysis of advanced attack helicopter composite main rotor blade root end lug (1982)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Stress analysis of the Advanced Attack Helicopter (AAH) composite main rotor blade root end lug is described. The stress concentration factor determined from a finite element analysis is compared to an empirical value used in the lug design. The analysis and test data indicate that the stress concentration is primarily a function of configuration and independent of the range of material properties typical of Kevlar-49/epoxy and glass epoxy.
    Keywords: COMPOSITE MATERIALS
    Type: NASA-TM-84578 , NAS 1.15:84578
    Format: application/pdf
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