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  • Aerospace Medicine  (2)
  • Structural Mechanics  (2)
  • 2000-2004  (4)
  • 2004  (4)
  • 1
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    Experimental Results From Stitched Composite Multi-Bay Fuselage Panels Tested Under Uni-Axial Compression (2004)
    In:  CASI
    Details
    Publication Date: 2019-07-10
    Description: The experimental results from two stitched VARTM composite panels tested under uni-axial compression loading are presented. The curved panels are divided by frames and stringers into five or six bays with a column of three bays along the compressive loading direction. The frames are supported at the ends to resist out-of-plane translation. Back-to-back strain gages are used to record the strain and displacement transducers were used to record the out-of-plane displacements. In addition a full-field measurement technique that utilizes a camera-based-stero-vision system was used to record displacements. The panels were loaded in increments to determine the first bay to buckle. Loading was discontinued at limit load and the panels were removed from the test machine for impact testing. After impacting at 20 ft-lbs to 25 ft-lbs of energy with a spherical indenter, the panels were loaded in compression until failure. Impact testing reduced the axial stiffness 4 percent and less than 1 percent. Postbuckled axial panel stiffness was 52 percent and 70 percent of the pre-buckled stiffness.
    Keywords: Structural Mechanics
    Type: NASA/TM-2004-213262 , ARL-TR-3233 , L-19031
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 2
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    Test and Analyses of a Composite Multi-Bay Fuselage Panel Under Uni-Axial Compression (2004)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: A composite panel containing three stringers and two frames cut from a vacuum-assisted resin transfer molded (VaRTM) stitched fuselage article was tested under uni-axial compression loading. The stringers and frames divided the panel into six bays with two columns of three bays each along the compressive loading direction. The two frames were supported at the ends with pins to restrict the out-of-plane translation. The free edges of the panel were constrained by knife-edges. The panel was modeled with shell finite elements and analyzed with ABAQUS nonlinear solver. The nonlinear predictions were compared with the test results in out-of-plane displacements, back-to-back surface strains on stringer flanges and back-to-back surface strains at the centers of the skin-bays. The analysis predictions were in good agreement with the test data up to post-buckling.
    Keywords: Structural Mechanics
    Type: AIAA Paper 2004-2056 , 45th AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics, and Materials Conference; Apr 19, 2004 - Apr 22, 2004; Palm Springs, CA; United States
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 3
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    Escherichia coli growth under modeled reduced gravity (2004)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: Bacteria exhibit varying responses to modeled reduced gravity that can be simulated by clino-rotation. When Escherichia coli was subjected to different rotation speeds during clino-rotation, significant differences between modeled reduced gravity and normal gravity controls were observed only at higher speeds (30-50 rpm). There was no apparent affect of removing samples on the results obtained. When E. coli was grown in minimal medium (at 40 rpm), cell size was not affected by modeled reduced gravity and there were few differences in cell numbers. However, in higher nutrient conditions (i.e., dilute nutrient broth), total cell numbers were higher and cells were smaller under reduced gravity compared to normal gravity controls. Overall, the responses to modeled reduced gravity varied with nutrient conditions; larger surface to volume ratios may help compensate for the zone of nutrient depletion around the cells under modeled reduced gravity.
    Keywords: Aerospace Medicine
    Type: Microgravity science and technology (ISSN 0938-0108); 15; 4; 39-44
    Format: text
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    NASA TECHNICAL REPORTS
  • 4
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    The effect of simulated microgravity on bacteria from the Mir space station (2004)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: The effects of simulated microgravity on two bacterial isolates, Sphingobacterium thalpophilium and Ralstonia pickettii (formerly Burkholderia pickettii), originally recovered from water systems aboard the Mir space station were examined. These bacteria were inoculated into water, high and low concentrations of nutrient broth and subjected to simulated microgravity conditions. S. thalpophilium (which was motile and had flagella) showed no significant differences between simulated microgravity and the normal gravity control regardless of the method of enumeration and medium. In contrast, for R. pickettii (that was non-motile and lacked flagella), there were significantly higher numbers in high nutrient broth under simulated microgravity compared to normal gravity. Conversely, when R. pikkettii was inoculated into water (i.e., starvation conditions) significantly lower numbers were found under simulated microgravity compared to normal gravity. Responses to microgravity depended on the strain used (e.g., the motile strain exhibited no response to microgravity, while the non-motile strain did), the method of enumeration, and the nutrient concentration of the medium. Under oligotrophic conditions, non-motile cells may remain in geostationary orbit and deplete nutrients in their vicinity, while in high nutrient medium, resources surrounding the cell may be sufficient so that high growth is observed until nutrients becoming limiting.
    Keywords: Aerospace Medicine
    Type: Microgravity science and technology (ISSN 0938-0108); 15; 1; 35-41
    Format: text
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    NASA TECHNICAL REPORTS
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