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  • 1
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    Thermal stress analysis of a silicon carbide/aluminum composite (1991)
    In:  Other Sources
    Details
    Publication Date: 2011-08-24
    Description: Thermal deformations and stresses were studied in a silicon-carbide/aluminum filamentary composite at temperatures up to 370 C (700 F). Longitudinal and transverse thermal strains were measured with strain gages and a dilatometer. An elastoplastic micromechanical analysis based on a one-dimensional rule-of-mixtures model and an axisymmetric two-material composite cylinder model was performed. It was established that beyond a critical temperature thermal strains become nonlinear with decreasing longitudinal and increasing transverse thermal-expansion coefficients. This behavior was attributed to the plastic stresses in the aluminum matrix above the critical temperature. An elastoplastic analysis of both micromechanical models was performed to determine the stress distributions and thermal deformation in the fiber and matrix of the composite. While only axial stresses can be determined by the rule-of-mixtures model, the complete triaxial state of stress is established by the composite cylinder model. Theoretical predictions for the two thermal-expansion coefficients were in satisfactory agreement with experimental results.
    Keywords: STRUCTURAL MECHANICS
    Type: Experimental Mechanics (ISSN 0014-4851); 31; 3, Se; 202-208
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  • 2
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    Test/semi-empirical analysis of a carbon/epoxy fabric stiffened panel (1990)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: The purpose of this work-in-progress is to present a semi-empirical analysis method developed to predict the buckling and crippling loads of carbon/epoxy fabric blade stiffened panels in compression. This is a hand analysis method comprised of well known, accepted techniques, logical engineering judgements, and experimental data that results in conservative solutions. In order to verify this method, a stiffened panel was fabricated and tested. Both the best and analysis results are presented.
    Keywords: STRUCTURAL MECHANICS
    Type: NASA, Langley Research Center, Research in Structures, Structural Dynamics, and Materials, 1990; p 3-35
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  • 3
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    Full-scale testing and analysis of fuselage structure (1994)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: This paper presents recent results from a program in the Boeing Commercial Airplane Group to study the behavior of cracks in fuselage structures. The goal of this program is to improve methods for analyzing crack growth and residual strength in pressurized fuselages, thus improving new airplane designs and optimizing the required structural inspections for current models. The program consists of full-scale experimental testing of pressurized fuselage panels in both wide-body and narrow-body fixtures and finite element analyses to predict the results. The finite element analyses are geometrically nonlinear with material and fastener nonlinearity included on a case-by-case basis. The analysis results are compared with the strain gage, crack growth, and residual strength data from the experimental program. Most of the studies reported in this paper concern the behavior of single or multiple cracks in the lap joints of narrow-body airplanes (such as 727 and 737 commercial jets). The phenomenon where the crack trajectory is curved creating a 'flap' and resulting in a controlled decompression is discussed.
    Keywords: STRUCTURAL MECHANICS
    Type: NASA. Langley Research Center, FAA(NASA International Symposium on Advanced Structural Integrity Methods for Airframe Durability and Damage Tolerance; p 481-496
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  • 4
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    Thermal/structural analysis of a transpiration cooled nozzle (1992)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: The 8-foot High Temperature Tunnel (HTT) at LaRC is a combustion driven, high enthalpy blow down wind tunnel. In Mar. 1991, during check out of the transpiration cooled nozzle, pieces of platelets were found in the tunnel test section. It was determined that incorrect tolerancing between the platelets and the housing was the primary cause of the platelet failure. An analysis was performed to determine the tolerance layout between the platelets and the housing to meet the structural and performance criteria under a range of thermal, pressure, and bolt preload conditions. Three recommendations resulted as a product of this analysis.
    Keywords: STRUCTURAL MECHANICS
    Type: NASA-TM-104184 , NAS 1.15:104184
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  • 5
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    NASA-UVA light aerospace alloy and structures technology program (LA2ST) (1994)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: The NASA-UVA Light Aerospace Alloy and Structures Technology (LA2ST) Program was initiated in 1986, and continues a high level of activity, with projects being conducted by graduate students and faculty advisors in the Departments of Materials Science and Engineering, and Mechanical and Aerospace Engineering at the University of Virginia. This work is funded by the NASA-Langley Research Center under Grant NAG-1-745. Here, we report on progress achieved between July 1 and December 31, 1993. The objective of the LA2ST Program is to conduct interdisciplinary graduate student research on the performance of next generation, light weight aerospace alloys, composites and thermal gradient structures in collaboration with NASA-Langley researchers. Specific technical objectives are presented for each research project. We generally aim to produce relevant data and basic understanding of material mechanical response, environmental/corrosion behavior, and microstructure; new monolithic and composite alloys; advanced processing methods; new solid and fluid mechanics analyses; measurement and modeling advances; and critically, a pool of educated graduate students for aerospace technologies.
    Keywords: STRUCTURAL MECHANICS
    Type: NASA-CR-195275 , NAS 1.26:195275 , UVA/528266/MSE94/114
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  • 6
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    Nonlinear static and dynamic finite element analysis of an eccentrically loaded graphite-epoxy beam (1991)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: The Dynamic Crash Analysis of Structures (DYCAT) and NIKE3D nonlinear finite element codes were used to model the static and implulsive response of an eccentrically loaded graphite-epoxy beam. A 48-ply unidirectional composite beam was tested under an eccentric axial compressive load until failure. This loading configuration was chosen to highlight the capabilities of two finite element codes for modeling a highly nonlinear, large deflection structural problem which has an exact solution. These codes are currently used to perform dynamic analyses of aircraft structures under impact loads to study crashworthiness and energy absorbing capabilities. Both beam and plate element models were developed to compare with the experimental data using the DYCAST and NIKE3D codes.
    Keywords: STRUCTURAL MECHANICS
    Type: AIAA PAPER 91-1227 , AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics, and Materials Conference; Apr 08, 1991 - Apr 10, 1991; Baltimore, MD; United States
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  • 7
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    Integrated modeling and analysis of a space-truss article (1990)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: MSC/NASTRAN is being used in the Controls-Structures Interaction (CSI) program at NASA Langley Research Center as a key analytical tool for structural analysis as well as the basis for control law development, closed-loop performance evaluation, and system safety checks. Guest investigators from academia and industry are performing dynamics and control experiments on a flight-like deployable space truss called Mini-Mast to determine the effectiveness of various active-vibration control laws. MSC/NASTRAN was used to calculate natural frequencies and mode shapes below 100 Hz to describe the dynamics of the 20-meter-long lightweight Mini-Mast structure. Gravitational effects contribute significantly to structural stiffness and are accounted for through a two-phase solution in which the differential stiffness matrix is calculated and then used in the eigensolution. Reduced modal models are extracted for control law design and evaluation of closed-loop system performance. Predicted actuator forces from controls simulations are then applied to the extended model to predict member loads and stresses. These pre-test analyses reduce risks associated with the structural integrity of the test article, which is a major concern in closed-loop control experiments due to potential instabilities.
    Keywords: STRUCTURAL MECHANICS
    Type: NASA-TM-102615 , NAS 1.15:102615 , MSC World Users'' Conference; Mar 26, 1990 - Mar 30, 1990; Los Angeles, CA; United States
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  • 8
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    Development of an experimental space station model for structural dynamics research (1990)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Design, analysis, and testing of an experimental space station scale model is presented. The model contains hardware components with dynamic characteristics similar to those expected for other large space structures. Validation of analysis models is achieved through correlation with dynamic tests of hardware components and representative assembly configurations. A component mode synthesis analysis method is examined through comparisons with results from fully mated system models. Selection of input requirements for accurate component synthesis analysis predictions are assessed.
    Keywords: STRUCTURAL MECHANICS
    Type: NASA-TM-102601 , NAS 1.15:102601 , Shock and Vibration Symposium; Nov 14, 1989 - Nov 16, 1989; Virginia Beach, VA; United States
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  • 9
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    Micromechanics thermal stress analysis of composites for space structure applications (1991)
    In:  Other Sources
    Details
    Publication Date: 2011-08-24
    Description: This paper presents results from a finite element micromechanics analysis of thermally induced stresses in composites at cryogenic temperatures typical of spacecraft operating environments. The influence of microstructural geometry, constituent and interphase properties, and laminate orientation were investigated. Stress field results indicated that significant matrix stresses occur in composites exposed to typical spacecraft thermal excursions; these stresses varied with laminate orientation and circumferential position around the fiber. The major difference in the predicted response of unidirectional and multidirectional laminates was the presence of tensile radial stresses, at the fiber/matrix interface, in multidirectional laminates with off-axis ply angles greater than 15 deg. The predicted damage initiation temperatures and modes were in good agreement with experimental data for both low (207 GPa) and high (517 GPa) modulus carbon fiber/epoxy composites.
    Keywords: STRUCTURAL MECHANICS
    Type: In: Mechanics of composites at elevated and cryogenic temperatures; Proceedings of the Symposium, ASME Applied Mechanics Conference, Columbus, OH, June 16-19, 1991 (A93-32451 12-39); p. 79-90.
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  • 10
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    Large-amplitude finite element flutter analysis of composite panels in hypersonic flow (1993)
    In:  Other Sources
    Details
    Publication Date: 2011-08-24
    Keywords: STRUCTURAL MECHANICS
    Type: AIAA Journal (ISSN 0001-1452); 31; 6; p. 1090-1099.
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