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  • 1
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    Residual strength prediction of damaged composite fuselage panel with R-curve method (2006)
    Elsevier
    Details
    Publication Date: 2006-11-01
    Print ISSN: 0266-3538
    Electronic ISSN: 1879-1050
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Published by Elsevier
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    PAPER CURRENT
  • 2
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    Correlation of Structural Analysis and Test Results for the McDonnell Douglas Stitched/RFI All-Composite Wing Stub Box (1996)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: The analytical and experimental results of an all-composite wing stub box are presented in this report. The wing stub box, which is representative of an inboard portion of a commercial transport high-aspect-ratio wing, was fabricated from stitched graphite-epoxy material with a Resin Film Infusion manufacturing process. The wing stub box was designed and constructed by the McDonnell Douglas Aerospace Company as part of the NASA Advanced Composites Technology program. The test article contained metallic load-introduction structures on the inboard and outboard ends of the graphite-epoxy wing stub box. The root end of the inboard load introduction structure was attached to a vertical reaction structure, and an upward load was applied to the outermost tip of the outboard load introduction structure to induce bending of the wing stub box. A finite element model was created in which the center portion of the wing-stub-box upper cover panel was modeled with a refined mesh. The refined mesh was required to represent properly the geometrically nonlinear structural behavior of the upper cover panel and to predict accurately the strains in the stringer webs of the stiffened upper cover panel. The analytical and experimental results for deflections and strains are in good agreement.
    Keywords: Structural Mechanics
    Type: NASA-TM-110267 , NAS 1.15:110267
    Format: application/pdf
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  • 3
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    Global and Local Stress Analyses of McDonnell Douglas Stitched/RFI Composite Wing Stub Box (1996)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: This report contains results of structural analyses performed in support of the NASA structural testing of an all-composite stitched/RFI (resin film infusion) wing stub box. McDonnell Douglas Aerospace Company designed and fabricated the wing stub box. The analyses used a global/local approach. The global model contains the entire test article. It includes the all-composite stub box, a metallic load-transition box and a metallic wing-tip extension box. The two metallic boxes are connected to the inboard and outboard ends of the composite wing stub box, respectively. The load-transition box was attached to a steel and concrete vertical reaction structure and a load was applied at the tip of the extension box to bend the wing stub box upward. The local model contains an upper cover region surrounding three stringer runouts. In that region, a large nonlinear deformation was identified by the global analyses. A more detailed mesh was used for the local model to obtain more accurate analysis results near stringer runouts. Numerous analysis results such as deformed shapes, displacements at selected locations, and strains at critical locations are included in this report.
    Keywords: Structural Mechanics
    Type: NASA-TM-110171 , NAS 1.26:110171
    Format: application/pdf
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  • 4
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    Buckling Analysis of Debonded Sandwich Panel Under Compression (1995)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: A sandwich panel with initial through-the-width debonds is analyzed to study the buckling of its faceskin when subject to an in-plane compressive load. The debonded faceskin is modeled as a beam on a Winkler elastic foundation in which the springs of the elastic foundation represent the sandwich foam. The Rayleigh-Ritz and finite-difference methods are used to predict the critical buckling load for various debond lengths and stiffnesses of the sandwich foam. The accuracy of the methods is assessed with a plane-strain finite-element analysis. Results indicate that the elastic foundation approach underpredicts buckling loads for sandwich panels with isotropic foam cores.
    Keywords: Structural Mechanics
    Type: NASA-TM-4701 , L-17476 , NAS 1.15:4701
    Format: application/pdf
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  • 5
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    An analytically designed subcomponent test to reproduce the failure of a composite wing box beam (1993)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: A Stiffener Runout Test Specimen (SRTS) has been analyzed and tested to verify the failure scenario for a large composite wingbox beam subcomponent. The SRTS was taken from an undamaged region of the subcomponent that was similar to the failure region of the boxbeam. Extensive analyses were performed to determine the proper load introduction and constraint conditions required for the SRTS test to simulate the response of the subcomponent. The present paper describes the analyses that led to the design of test fixtures that ensured that the response of the SRTS duplicated the response of the box beam. The results of the SRTS test are described and compared with the analytical predictions.
    Keywords: AIRCRAFT DESIGN, TESTING AND PERFORMANCE
    Type: AIAA PAPER 93-1344 , In: AIAA(ASME)ASCE/AHS/ASC Structures, Structural Dynamics, and Materials Conference, 34th and AIAA/ASME Adaptive Structures Forum, La Jolla, CA, Apr. 19-22, 1993, Technical Papers. Pt. 1 (A93-33876 1; p. 424-435.
    Format: text
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  • 6
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    Evaluation of a Progressive Failure Analysis Methodology for Laminated Composite Structures (1997)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: A progressive failure analysis methodology has been developed for predicting the nonlinear response and failure of laminated composite structures. The progressive failure analysis uses C plate and shell elements based on classical lamination theory to calculate the in-plane stresses. Several failure criteria, including the maximum strain criterion, Hashin's criterion, and Christensen's criterion, are used to predict the failure mechanisms. The progressive failure analysis model is implemented into a general purpose finite element code and can predict the damage and response of laminated composite structures from initial loading to final failure.
    Keywords: Composite Materials
    Type: AIAA Paper 97-1187 , AIAA/ASME/ASCE/AHS/ASC 38th Structures, Structural Dynamics and Materials Conference; Apr 07, 1997 - Apr 10, 1997; United States
    Format: application/pdf
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  • 7
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    Continuum Damage Mechanics Based Explicit 3D Progressive Failure Analysis of Composite Laminates (2015)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: No abstract available
    Keywords: Structural Mechanics
    Type: NF1676L-21070 , The Aircraft Airworthiness and Sustainment Conference; May 30, 2015 - Apr 02, 2015; Baltimore, MD; United States
    Format: application/pdf
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  • 8
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    Structural Integrity Testing Method for PRSEUS Rod-Wrap Stringer Design (2012)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: NASA Langley Research Center and The Boeing Company are developing an innovative composite structural concept, called PRSEUS, for the flat center section of a future environmentally friendly hybrid wing body (HWB) aircraft. The PRSEUS (Pultruded Rod Stitched Efficient Unitized Structure) concept uses dry textile preforms for the skins, frames, and stiffener webs. The highly loaded stiffeners are made from precured unidirectional carbon/epoxy rods and dry fiber preforms. The rods are wrapped with the dry fiber preforms and a resin infusion process is used to form the rod-wrap stiffeners. The structural integrity of the rod-wrap interface is critical for maintaining the panel s high strength and bending rigidity. No standard testing method exists for testing the strength of the rod-wrap bondline. Recently, Boeing proposed a rod push-out testing method and conducted some preliminary tests using this method. This paper details an analytical study of the rod-wrap bondline. The rod-wrap interface is modeled as a cohesive zone for studying the initiation and growth of interfacial debonding during push-out testing. Based on the correlations of analysis results and Boeing s test data, the adequacy of the rod-wrap testing method is evaluated, and potential approaches for improvement of the test method are proposed.
    Keywords: Composite Materials
    Type: AIAA Paper 2012-1861 , NF1676L-13292 , 53rd AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics and Materials Conference; Apr 23, 2012 - Apr 26, 2012; Honolulu, HI; United States
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  • 9
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    Investigating Some Technical Issues on Cohesive Zone Modeling of Fracture (2011)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: This study investigates some technical issues related to the use of cohesive zone models (CZMs) in modeling fracture processes. These issues include: why cohesive laws of different shapes can produce similar fracture predictions; under what conditions CZM predictions have a high degree of agreement with linear elastic fracture mechanics (LEFM) analysis results; when the shape of cohesive laws becomes important in the fracture predictions; and why the opening profile along the cohesive zone length needs to be accurately predicted. Two cohesive models were used in this study to address these technical issues. They are the linear softening cohesive model and the Dugdale perfectly plastic cohesive model. Each cohesive model constitutes five cohesive laws of different maximum tractions. All cohesive laws have the same cohesive work rate (CWR) which is defined by the area under the traction-separation curve. The effects of the maximum traction on the cohesive zone length and the critical remote applied stress are investigated for both models. For a CZM to predict a fracture load similar to that obtained by an LEFM analysis, the cohesive zone length needs to be much smaller than the crack length, which reflects the small scale yielding condition requirement for LEFM analysis to be valid. For large-scale cohesive zone cases, the predicted critical remote applied stresses depend on the shape of cohesive models used and can significantly deviate from LEFM results. Furthermore, this study also reveals the importance of accurately predicting the cohesive zone profile in determining the critical remote applied load.
    Keywords: Structural Mechanics
    Type: NF1676L-12350 , 52nd AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics, and Materials Conference; Apr 04, 2011 - Apr 07, 2011; Denver, CO; United States
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  • 10
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    A Feasibility Study of Synthesizing Subsurfaces Modeled with Computational Neural Networks (1998)
    In:  CASI
    Details
    Publication Date: 2019-07-10
    Description: This paper investigates the feasibility of synthesizing substructures modeled with computational neural networks. Substructures are modeled individually with computational neural networks and the response of the assembled structure is predicted by synthesizing the neural networks. A superposition approach is applied to synthesize models for statically determinate substructures while an interface displacement collocation approach is used to synthesize statically indeterminate substructure models. Beam and plate substructures along with components of a complicated Next Generation Space Telescope (NGST) model are used in this feasibility study. In this paper, the limitations and difficulties of synthesizing substructures modeled with neural networks are also discussed.
    Keywords: Engineering (General)
    Type: AIAA Paper 98-1778
    Format: application/pdf
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