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  • 1975-1979  (7)
  • 1
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    Pressure and heating-rate distributions on a corrugated surface in a supersonic turbulent boundary layer (1977)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Drag and heating rates on wavy surfaces typical of current corrugated plate designs for thermal protection systems were determined experimentally. Pressure-distribution, heating-rate, and oil-flow tests were conducted in the Langley Unitary Plan wind tunnel at Mach numbers of 2.4 and 4.5 with the corrugated surface exposed to both thick and thin turbulent boundary layers. Tests were conducted with the corrugations at cross-flow angles from 0 deg to 90 deg to the flow. Results show that for cross-flow angles of 30 deg or less, the pressure drag coefficients are less than the local flat-plate skin-friction coefficients and are not significantly affected by Mach number, Reynolds number, or boundary-layer thickness over the ranges investigated. For cross-flow angles greater than 30 deg, the drag coefficients increase significantly with cross-flow angle and moderately with Reynolds number. Increasing the Mach number causes a significant reduction in the pressure drag. The average and peak heating penalties due to the corrugated surface are small for cross-flow angles of 10 deg or less but are significantly higher for the larger cross-flow angles.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-TP-1024 , L-11732 , NAS 1.60:1024
    Format: application/pdf
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  • 2
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    Flutter of laminated plates in supersonic flow (1975)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: A solution procedure was developed using linear small deflection theory for the flutter of simply supported laminated plates. For such plates, the bending and extensional governing equations are coupled and have cross-stiffness terms which do not appear in classical plate theory. An extended Galerkin method is used to obtain approximate solutions to the governing equations, and the aerodynamic pressure loading used in the analysis is that given by linear piston theory with flow at arbitrary cross-flow angle. A limited parametric study was conducted for typical laminated composite plates. The calculations show that both the bending-extensional coupling and the cross-stiffness terms have a large destabilizing effect on flutter. Since classical plate theory does not consider bending-extensional coupling and cross stiffness terms, it usually gives inaccurate and nonconservative flutter boundaries for laminated plates.
    Keywords: AERODYNAMICS
    Type: NASA-TM-X-72800
    Format: application/pdf
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  • 3
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    Supersonic flutter of panels loaded with inplane shear (1975)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: A modal flutter analysis for biaxially loaded, orthotropic panels, using linear piston-theory aerodynamics, was extended in order to include the effects of inplane shear loading. Flutter boundaries for shear loads up to buckling are calculated for simply supported, isotropic panels of various length-width ratios and for a square, isotropic panel with elastic boundary conditions along the leading and trailing edges. These flutter boundaries are used to define conservative design curves. Sample calculations made using these design curves indicate that practical panels, which have otherwise been adequately designed, could become flutter critical if the inplane shear loads approach the buckling value.
    Keywords: STRUCTURAL MECHANICS
    Type: NASA-TN-D-7888 , L-9908
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  • 4
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    Flutter and buckling of general laminated plates (1976)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: An anisotropic buckling and flutter analysis is developed with allowance for both bending-extensional coupling and bending-twisting coupling within the framework of linear small deflection theory for simply supported general laminated plates. The extended Galerkin method is used to obtain approximate solutions to the coupled governing equations. The effects of various anisotropic stiffness parameters on the static and dynamic stability of laminated plates are evaluated, with particular emphasis on assessing the range of applicability of classical orthotropic plate theory. It is shown that bending-extensional coupling and bending-twisting stiffness terms have a destabilizing effect on buckling and flutter, the effect being more pronounced for a small number of layers. For symmetric plates, the number of layers required for orthotropic plate theory to be applicable is generally less for the buckling problem than for flutter. For square plates, aligning the fibers with the direction of airflow over the plate surface results in the highest flutter dynamic pressure.
    Keywords: STRUCTURAL MECHANICS
    Type: Structures, Structural Dynamics, and Materials Conference; May 05, 1976 - May 07, 1976; King of Prussia, PA
    Format: text
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  • 5
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    Performance of full size metallic and RSI thermal protection systems in a Mach 7 environment (1975)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: The integrity and reusability of three flight-weight metallic and RSI thermal protection systems, designed for the Shuttle entry environment, have been demonstrated. Each model successfully survived over 23 entry thermal cycles without serious degradation. The metallic systems were more tolerant of the hostile environment and provided a higher degree of reusability than did the RSI. Thermal expansion slip joints of the metallic TPS successfully prevented hot gas ingress to the substructure. The RSI demonstrated high damage tolerance and field repairs increased its reusability. Heat-transfer tests to further assess RSI gap heating indicate that stacked tile orientations may impose a penalty on tile thickness. Parameters influencing RSI impingement heating were determined, and the heating data were correlated.
    Keywords: METALLIC MATERIALS
    Type: AIAA PAPER 75-800 , AIAA, ASME, and SAE, Structures, Structural Dynamics, and Materials Conference; May 27, 1975 - May 29, 1975; Denver, CO
    Format: text
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  • 6
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    A critical examination of stresses in an elastic single lap joint (1979)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: The results of an approximate nonlinear finite-element analysis of a single lap joint are presented and compared with the results of a linear finite-element analysis, and the geometric nonlinear effects caused by the load-path eccentricity on the adhesive stress distributions are determined. The results from finite-element, Goland-Reissner, and photoelastic analyses show that for a single lap joint the effect of the geometric nonlinear behavior of the joint has a sizable effect on the stresses in the adhesive. The Goland-Reissner analysis is sufficiently accurate in the prediction of stresses along the midsurface of the adhesive bond to be used for qualitative evaluation of the influence of geometric or material parametric variations. Detailed stress distributions in both the adherend and adhesive obtained from the finite-element analysis are presented to provide a basis for comparison with other solution techniques.
    Keywords: STRUCTURAL MECHANICS
    Type: NASA-TP-1507 , L-12802
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  • 7
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    Aerothermal and structural performance of a cobalt-base superalloy thermal protection system at Mach 6.6 (1977)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: A flightweight, metallic thermal protection system (TPS) applicable to reentry and hypersonic vehicles was subjected to multiple cycles of both radiant and aerothermal heating in order to evaluate its aerothermal performance and structural integrity. Good structural integrity and thermal performance were demonstrated by the TPS under both a radiant and aerothermal heating environment typical of a shuttle entry. The shingle-slip joints effectively allowed for thermal expansion of the panel without allowing any appreciable hot gas flow into the TPS cavity. The TPS also demonstrated good structural ruggedness.
    Keywords: STRUCTURAL MECHANICS
    Type: NASA-TN-D-8415 , L-11286
    Format: application/pdf
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