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  • 11
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    Progressive Damage Modeling of Durable Bonded Joint Technology (2013)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: The development of durable bonded joint technology for assembling composite structures for launch vehicles is being pursued for the U.S. Space Launch System. The present work is related to the development and application of progressive damage modeling techniques to bonded joint technology applicable to a wide range of sandwich structures for a Heavy Lift Launch Vehicle. The joint designs studied in this work include a conventional composite splice joint and a NASA-patented Durable Redundant Joint. Both designs involve a honeycomb sandwich with carbon/epoxy facesheets joined with adhesively bonded doublers. Progressive damage modeling allows for the prediction of the initiation and evolution of damage. For structures that include multiple materials, the number of potential failure mechanisms that must be considered increases the complexity of the analyses. Potential failure mechanisms include fiber fracture, matrix cracking, delamination, core crushing, adhesive failure, and their interactions. The joints were modeled using Abaqus parametric finite element models, in which damage was modeled with user-written subroutines. Each ply was meshed discretely, and layers of cohesive elements were used to account for delaminations and to model the adhesive layers. Good correlation with experimental results was achieved both in terms of load-displacement history and predicted failure mechanisms.
    Keywords: Composite Materials
    Type: NF1676L-15977 , SAMPE 2013; May 06, 2013 - May 09, 2013; Long Beach, CA; United States
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 12
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    Fabrication and Testing of Durable Redundant and Fluted-Core Joints for Composite Sandwich Structures (2013)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: The development of durable bonded joint technology for assembling composite structures is an essential component of future space technologies. While NASA is working toward providing an entirely new capability for human space exploration beyond low Earth orbit, the objective of this project is to design, fabricate, analyze, and test a NASA patented durable redundant joint (DRJ) and a NASA/Boeing co-designed fluted-core joint (FCJ). The potential applications include a wide range of sandwich structures for NASA's future launch vehicles. Three types of joints were studied -- splice joint (SJ, as baseline), DRJ, and FCJ. Tests included tension, after-impact tension, and compression. Teflon strips were used at the joint area to increase failure strength by shifting stress concentration to a less sensitive area. Test results were compared to those of pristine coupons fabricated utilizing the same methods. Tensile test results indicated that the DRJ design was stiffer, stronger, and more impact resistant than other designs. The drawbacks of the DRJ design were extra mass and complex fabrication processes. The FCJ was lighter than the DRJ but less impact resistant. With barely visible but detectable impact damages, all three joints showed no sign of tensile strength reduction. No compression test was conducted on any impact-damaged sample due to limited scope and resource. Failure modes and damage propagation were also studied to support progressive damage modeling of the SJ and the DRJ.
    Keywords: Composite Materials
    Type: NF1676L-15302 , SAMPE 2013; May 06, 2013 - May 09, 2013; Long Beach, CA; United States
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    NASA TECHNICAL REPORTS
  • 13
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    Out of the Autoclave Fabrication of LaRC[TradeMark] PETI-9 Polyimide Laminates (2013)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: The NASA Langley Research Center developed polyimide system, LaRC PETI-9, has successfully been processed into composites by high temperature vacuum assisted resin transfer molding (HT-VARTM). To extend the application of this high use temperature material to other out-of-autoclave (OOA) processing techniques, the fabrication of PETI- 9 laminates was evaluated using only a vacuum bag and oven cure. A LaRC PETI-9 polyimide solution in NMP was prepared and successfully utilized to fabricate unidirectional IM7 carbon fiber prepreg that was subsequently processed into composites with a vacuum bag and oven cure OOA process. Composite panels of good quality were successfully fabricated and mechanically tested. Processing characteristics, composite panel quality and mechanical properties are presented in this work. The resultant properties are compared to previously developed LaRC material systems processed by both autoclave and OOA techniques including the well characterized, autoclave processed LaRC PETI-5.
    Keywords: Composite Materials
    Type: NF1676L-15055 , SAMPE 2013; May 06, 2013 - May 09, 2013; Long Beach, CA; United States
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  • 14
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    Stress Free Temperature Testing and Calculations on Out-of-Autoclave Composites (2013)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: No abstract available
    Keywords: Composite Materials
    Type: KSC-2013-038R , SAMPE 2013; May 06, 2013 - May 09, 2013; Long Beach, CA; United States
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    NASA TECHNICAL REPORTS
  • 15
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    Behavior of Frame-Stiffened Composite Panels with Damage (2013)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: NASA, the Air Force Research Laboratory and The Boeing Company have worked to develop new low-cost, light-weight composite structures for aircraft. A Pultruded Rod Stitched Efficient Unitized Structure (PRSEUS) concept has been developed which offers advantages over traditional metallic structures. In this concept, a stitched carbon-epoxy material system has been developed with the potential for reducing the weight and cost of transport aircraft structure by eliminating fasteners, thereby reducing part count and labor. Stitching and the use of thin skins with rod-stiffeners to move loading away from the morevulnerable outer surface produces a structurally efficient, damage tolerant design. This study focuses on the behavior of PRSEUS panels loaded in the frame direction and subjected to severe damage in the form of a severed central frame in a three-frame panel. Experimental results for a pristine two-frame panel and analytical predictions for pristine two-frame and three-frame panels as well as damaged three-frame panels are described.
    Keywords: Composite Materials
    Type: AIAA Paper 2013-1738 , NF1676L-15257 , 54th AIAA/ASME/ASCE/AHS/ASC, Structures, Structural Dynamics, and Materials Conference; Apr 08, 2013 - Apr 11, 2013; Boston, MA; United States
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    NASA TECHNICAL REPORTS
  • 16
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    Composite Australia Conference Composite Cryotank Project Structures for Launch Vehicles (2013)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: No abstract available
    Keywords: Composite Materials
    Type: M13-2455 , Composites Australia Conference and Trade Show; Mar 05, 2013 - Mar 06, 2013; Melbourne; Australia
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 17
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    Longitudinally Jointed Edge-Wise Compression HoneyComb Composite Sandwich Coupon Testing And Fe Analysis: Three Methods of Strain Measurement, And Comparison (2013)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Three distinct strain measurement methods (i.e., foil resistance strain gages, fiber optic strain sensors, and a three-dimensional digital image photogrammetry that gives full field strain and displacement measurements) were implemented to measure strains on the back and front surfaces of a longitudinally jointed curved test article subjected to edge-wise compression testing, at NASA Goddard Space Flight Center, according to ASTM C364. The pre-test finite element analysis (FEA) was conducted to assess ultimate failure load and predict strain distribution pattern throughout the test coupon. The predicted strain pattern contours were then utilized as guidelines for installing the strain measurement instrumentations. The foil resistance strain gages and fiber optic strain sensors were bonded on the specimen at locations with nearly the same analytically predicted strain values, and as close as possible to each other, so that, comparisons between the measured strains by strain gages and fiber optic sensors, as well as the three-dimensional digital image photogrammetric system are relevant. The test article was loaded to failure (at ~167 kN), at the compressive strain value of ~10,000 micro epsilon. As a part of this study, the validity of the measured strains by fiber optic sensors is examined against the foil resistance strain gages and the three-dimensional digital image photogrammetric data, and comprehensive comparisons are made with FEA predictions.
    Keywords: Composite Materials
    Type: GSFC.CP.7538.2013 , SAMPE 2013 Conference; May 06, 2013 - May 09, 2013; Long Beach, CA; United States
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    NASA TECHNICAL REPORTS
  • 18
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    Prediction of Composite Laminate Strength Properties Using a Refined Zigzag Plate Element (2013)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: This study presents an approach that uses the refined zigzag element, RZE(exp2,2) in conjunction with progressive failure criteria to predict the ultimate strength of composite laminates based on only ply-level strength properties. The methodology involves four major steps: (1) Determination of accurate stress and strain fields under complex loading conditions using RZE(exp2,2)-based finite element analysis, (2) Determination of failure locations and failure modes using the commonly accepted Hashin's failure criteria, (3) Recursive degradation of the material stiffness, and (4) Non-linear incremental finite element analysis to obtain stress redistribution until global failure. The validity of this approach is established by considering the published test data and predictions for (1) strength of laminates under various off-axis loading, (2) strength of laminates with a hole under compression, and (3) strength of laminates with a hole under tension.
    Keywords: Composite Materials
    Type: AIAA Paper 2013-1539 , NF1676L-16317 , 54th AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics and Materials Conference; Apr 08, 2013 - Apr 11, 2013; Boston, MA; United States
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    NASA TECHNICAL REPORTS
  • 19
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    Arcjet Testing of Woven Carbon Cloth for Use on Adaptive Deployable Entry Placement Technology (2013)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: This paper describes arcjet testing and analysis that has successfully demonstrated the viability of three dimensional woven carbon cloth for dual use in the Adaptive Deployable Entry Placement Technology (ADEPT). ADEPT is an umbrella-like entry system that is folded for stowage in the launch vehicle s shroud and deployed in space prior to reaching the atmospheric interface. A key feature of the ADEPT concept is its lower ballistic coefficient for delivery of a given payload than those for conventional, rigid body entry systems. The benefits that accrue from the lower ballistic coefficient include factor of ten reductions of deceleration forces and entry heating. The former enables consideration of new classes of scientific instruments for solar system exploration while the latter enables the design of a more efficient thermal protection system. The carbon cloth now base lined for ADEPT has a dual use in that it serves as ADEPT s thermal protection system and as the "skin" that transfers aerodynamic deceleration loads to its umbrella-like substructure. The arcjet testing described in this paper was conducted for some of the higher heating conditions for a future Venus mission using the ADEPT concept, thereby showing that the carbon cloth can perform in a relevant entry environment. The ADEPT project considered the carbon cloth to be mission enabling and was carrying it as a major risk during Fiscal Year 2012. The testing and analysis reported here played a major role in retiring that risk and is highly significant to the success and possible adoption of ADEPT for future NASA missions. Finally, this paper also describes a preliminary engineering level code, based on the arcjet data, that can be used to estimate cloth thickness for future missions using ADEPT and to predict carbon cloth performance in future arcjet tests.
    Keywords: Composite Materials
    Type: ARC-E-DAA-TN6341 , 2013 IEEE Aerospace Conference; Mar 02, 2013 - Mar 09, 2013; Big Sky, MT; United States
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  • 20
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    Evaluation of Ceramic Matrix Composite Technology for Aircraft Turbine Engine Applications (2013)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: The goals of the NASA Environmentally Responsible Aviation (ERA) Project are to reduce the NO(x) emissions, fuel burn, and noise from turbine engines. In order to help meet these goals, commercially-produced ceramic matrix composite (CMC) components and environmental barrier coatings (EBCs) are being evaluated as parts and panels. The components include a CMC combustor liner, a CMC high pressure turbine vane, and a CMC exhaust nozzle as well as advanced EBCs that are tailored to the operating conditions of the CMC combustor and vane. The CMC combustor (w/EBC) could provide 2700 F temperature capability with less component cooling requirements to allow for more efficient combustion and reductions in NOx emissions. The CMC vane (w/EBC) will also have temperature capability up to 2700 F and allow for reduced fuel burn. The CMC mixer nozzle will offer reduced weight and improved mixing efficiency to provide reduced fuel burn. The main objectives are to evaluate the manufacturability of the complex-shaped components and to evaluate their performance under simulated engine operating conditions. Progress in CMC component fabrication, evaluation, and testing is presented in which the goal is to advance from the proof of concept validation (TRL 3) to a system/subsystem or prototype demonstration in a relevant environment (TRL 6).
    Keywords: Composite Materials
    Type: 41st AIAA Aerospace Sciences Meeting including the New Horizons Forum and Aerospace Exposition; Jan 07, 2013 - Jan 10, 2013; Grapevine, TX; United States
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