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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 217 records · Page 12
All sourcesNASA NTRSDOE OSTI
NASA NTRS1992

Composite fuselage crown panel manufacturing technology

Commercial fuselage structures contain significant challenges in attempting to save manufacturing costs with advanced composite technology. Assembly issues, materials costs, and fabrication of elements with complex geometry are each expected to drive the cost of composite fuselage structure. Key technologies, such as large crown panel fabrication, were pursued for low cost. An intricate bond panel design and manufacturing concept were selected based on the efforts of the Design Build Team. The manufacturing processes selected for the intricate bond design include multiple large panel fabrication with Advanced Tow Placement (ATP) process, innovative cure tooling concepts, resin transfer molding of long fuselage frames, and use of low cost materials forms. The process optimization for final design/manufacturing configuration included factory simulations and hardware demonstrations. These efforts and other optimization tasks were instrumental in reducing costs by 18 pct. and weight by 45 pct. relative to an aluminum baseline. The qualitative and quantitative results of the manufacturing demonstrations were used to assess manufacturing risks and technology readiness.

Willden, Kurtis↗
NASA NTRS1992

Composite fuselage crown panel manufacturing technology

Commercial fuselage structures contain significant challenges in attempting to save manufacturing costs with advanced composite technology. Assembly issues, material costs, and fabrication of elements with complex geometry are each expected to drive the cost of composite fuselage structures. Boeing's efforts under the NASA ACT program have pursued key technologies for low-cost, large crown panel fabrication. An intricate bond panel design and manufacturing concepts were selected based on the efforts of the Design Build Team (DBT). The manufacturing processes selected for the intricate bond design include multiple large panel fabrication with the Advanced Tow Placement (ATP) process, innovative cure tooling concepts, resin transfer molding of long fuselage frames, and utilization of low-cost material forms. The process optimization for final design/manufacturing configuration included factory simulations and hardware demonstrations. These efforts and other optimization tasks were instrumental in reducing cost by 18 percent and weight by 45 percent relative to an aluminum baseline. The qualitative and quantitative results of the manufacturing demonstrations were used to assess manufacturing risks and technology readiness.

Willden, Kurtis↗
NASA NTRS1973

Filament-wound composite vessels material technology

Programs are reviewed that were conducted to establish a technology base for applying advanced fibers or resins to high performance filament-wound pressure vessels for containment of cryogens and high pressure gases. Materials evaluated included boron, graphite, PRD 49-1 and 3/epoxy and S-glass/polyimide composites. Closed-end cylindrical, and oblate spheroid-shaped vessels were fabricated in 4- and 8-inch diameter sizes. Vessels were subjected to single-cycle burst, low-cycle fatigue, and sustained loading tests over a -423 F to room temperature range for epoxy composites and a -423 to 500 F temperature range for the polyimide composites. Vessels tested at cryogenic and/or 500 F had thin (3 to 20 mils) metallic liners whereas vessels tested at room temperature had elastomeric liners. Correlations between acoustic emissions and burst and cyclic properties of PRD 49-1 filament-wound vessels are discussed.

Lark, R. F.↗
NASA NTRS1994

Low-Dielectric-Constant Polyimide/Glass Composites

Advance in polymer technology yields composites having relatively low dielectric constants. Reduction achieved by reducing interactions between linear polyimide chains and by incorporation of fluorine into polymer backbones. Further reductions obtained by physically incorporating selected diamic acid additives into polyimides. Strong potential for use in microelectronics industry for fabrication of printed-circuit boards and fabrication of components for military aircraft.

Stoakley, Diane M.↗
NASA NTRS1982

Fuselage structure using advanced technology fiber reinforced composites

A fuselage structure is described in which the skin is comprised of layers of a matrix fiber reinforced composite, with the stringers reinforced with the same composite material. The high strength to weight ratio of the composite, particularly at elevated temperatures, and its high modulus of elasticity, makes it desirable for use in airplane structures.

Robinson, R. K.↗
NASA NTRS1988

Composite transport wing technology development

The design, fabrication, testing, and analysis of stiffened wing cover panels to assess damage tolerance criteria are discussed. The damage tolerance improvements were demonstrated in a test program using full-sized cover panel subcomponents. The panels utilized a hard skin concept with identical laminates of 44-percent 0-degree, 44-percent plus or minus 45-degree, and 12-percent 90-degree plies in the skins and stiffeners. The panel skins were impacted at midbay between the stiffeners, directly over the stiffener, and over the stiffener flange edge. The stiffener blades were impacted laterally. Impact energy levels of 100 ft-lb and 200 ft-lb were used. NASTRAN finite-element analyses were performed to simulate the nonvisible damage that was detected in the panels by nondestructive inspection. A closed-form solution for generalized loading was developed to evaluate the peel stresses in the bonded structure. Two-dimensional delamination growth analysis was developed using the principle of minimum potential energy in terms of closed-form solution for critical strain. An analysis was conducted to determine the residual compressive stress in the panels after impact damage, and the analytical predictions were verified by compression testing of the damaged panels.

Madan, Ram C.↗
NASA NTRS2015

Test and Analysis Correlation for a Y-Joint Specimen for a Composite Cryotank

The Composite Cryotank Technology Demonstration (CCTD) project under NASA's Game Changing Development Program (GCDP) developed space technologies using advanced composite materials. Under CCTD, NASA funded the Boeing Company to design and test a number of element-level joint specimens as a precursor to a 2.4-m diameter composite cryotank. Preliminary analyses indicated that the y-joint in the cryotank had low margins of safety; hence the y-joint was considered to be a critical design region. The y-joint design includes a softening strip wedge to reduce localized shear stresses at the skirt/dome interface. In this paper, NASA-developed analytical models will be correlated with the experimental results of a series of positive-peel y-joint specimens from Boeing tests. Initial analytical models over-predicted the experimental strain gage readings in the far-field region by approximately 10%. The over-prediction was attributed to uncertainty in the elastic properties of the laminate and a mismatch between the thermal expansion of the strain gages and the laminate. The elastic properties of the analytical model were adjusted to account for the strain gage differences. The experimental strain gages also indicated a large non-linear effect in the softening strip region that was not predicted by the analytical model. This non-linear effect was attributed to delamination initiating in the softening strip region at below 20% of the failure load for the specimen. Because the specimen was contained in a thermally insulated box during cryogenic testing to failure, delamination initiation and progression was not visualized during the test. Several possible failure initiation locations were investigated, and a most likely failure scenario was determined that correlated well with the experimental data. The most likely failure scenario corresponded to damage initiating in the softening strip and delamination extending to the grips at final failure.

Mason, Brian H.↗
NASA NTRS1984

Resistance-foil strain-gage technology as applied to composite materials

A general review of existing strain-gage technologies as applied to orthotropic-composite materials is given. The specific topics addressed are gage-bonding procedures, transverse-sensitivity effects, errors due to gage misalignment, and temperature-compensation methods. The discussion is supplemented by numerical examples where appropriate. It is shown that the orthotropic behavior of composites can result in experimental error which would not be expected based on practical experience with isotropic materials. In certain cases, the transverse sensitivity of strain gages and/or slight gage misalignment can result in strain-measurement errors exceeding 50 percent.

Tuttle, M. E.↗
NASA NTRS1998

Tooling Foam for Structural Composite Applications

Tooling technology applications for composite structures fabrication have been expanded at MSFC's Productivity Enhancement Complex (PEC). Engineers from NASA/MSFC and Lockheed Martin Corporation have developed a tooling foam for use in composite materials processing and manufacturing that exhibits superior thermal and mechanical properties in comparison with other tooling foam materials. This tooling foam is also compatible with most preimpregnated composite resins such as epoxy, bismaleimide, phenolic and their associated cure cycles. MARCORE tooling foam has excellent processability for applications requiring either integral or removable tooling. It can also be tailored to meet the requirements for composite processing of parts with unlimited cross sectional area. A shelf life of at least six months is easily maintained when components are stored between 50F - 70F. The MARCORE tooling foam system is a two component urethane-modified polyisocyanurate, high density rigid foam with zero ozone depletion potential. This readily machineable, lightweight tooling foam is ideal for composite structures fabrication and is dimensionally stable at temperatures up to 350F and pressures of 100 psi.

DeLay, Tom↗
NASA NTRS2004

Prepreg and Melt Infiltration Technology Developed for Affordable, Robust Manufacturing of Ceramic Matrix Composites

Affordable fiber-reinforced ceramic matrix composites with multifunctional properties are critically needed for high-temperature aerospace and space transportation applications. These materials have various applications in advanced high-efficiency and high-performance engines, airframe and propulsion components for next-generation launch vehicles, and components for land-based systems. A number of these applications require materials with specific functional characteristics: for example, thick component, hybrid layups for environmental durability and stress management, and self-healing and smart composite matrices. At present, with limited success and very high cost, traditional composite fabrication technologies have been utilized to manufacture some large, complex-shape components of these materials. However, many challenges still remain in developing affordable, robust, and flexible manufacturing technologies for large, complex-shape components with multifunctional properties. The prepreg and melt infiltration (PREMI) technology provides an affordable and robust manufacturing route for low-cost, large-scale production of multifunctional ceramic composite components.

Singh, Mrityunjay↗
NASA NTRS1996

Integrated Airframe Technology: The Future of Advanced Composites

The challenge for advanced composites in integrated airframe technology is that: airframes must provide ever increasing performance at an affordable cost; reduce costs as compared to current airframe technology; and integration of design and manufacturing. The trend in technology is that a gap exists between the potential of advanced composites and our ability to effectively utilize them (cost/weight).

Taggart, David F.↗
NASA NTRS1997

T/BEST: Technology Benefit Estimator for Composites and Applications to Engine Structures

Progress in the field of aerospace propulsion has heightened the need to combine advanced technologies. These benefits will provide guidelines for identifying and prioritizing high-payoff research areas, will help manage research with limited resources, and will show the link between advanced and basic concepts. An effort was undertaken at the NASA Lewis Research Center to develop a formal computational method, T/BEST (Technology Benefit Estimator), to assess advanced aerospace technologies, such as fibrous composites, and credibly communicate the benefits of research. Fibrous composites are ideal for structural applications such as high-performance aircraft engine blades where high strength-to-weight and stiffness-to-weight ratios are required. These factors - along with the flexibility to select the composite system and layup, and to favorably orient fiber directions - reduce the displacements and stresses caused by large rotational speeds in aircraft engines.

Chamis, Christos↗
NASA NTRS1981

Progress in composite structure and space construction systems technology

The development of deployable and fabricated composite trusses for large space structures by NASA and private industry is reviewed. Composite materials technology is discussed with a view toward fabrication processes and the characteristics of finished truss beams. Advances in roll-forming open section caps from graphite-composite strip material and new ultrasonic welding techniques are outlined. Vacuum- and gravity-effect test results show that the ultrasonic welding of graphite-thermoplastic materials in space is feasible. The structural characteristics of a prototype truss segment are presented. A new deployable graphite-composite truss with high packaging density for broad application to large space platforms is described.

Bodle, J. B.↗
NASA NTRS2001

Assessment of the State-of-the-Art in the Design and Manufacturing of Large Composite Structure

This viewgraph presentation gives an assessment of the state-of-the-art in the design and manufacturing of large component structures, including details on the use of continuous fiber reinforced polymer matrix composites (CFRP) in commercial and military aircraft and in space launch vehicles. Project risk mitigation plans must include a building-block test approach to structural design development, manufacturing process scale-up development tests, and pre-flight ground tests to verify structural integrity. The potential benefits of composite structures justifies NASA's investment in developing the technology. Advanced composite structures technology is enabling to virtually every Aero-Space Technology Enterprise Goal.

Harris, C. E.↗
NASA NTRSDate not supplied

Thermal Response of Thermoplastic Composite Tape During In-situ Consolidation Automated Fiber Placement Using a Laser Heat Source

Composite materials have tremendous potential in the design and manufacture of commercial aircraft due to their high strength-to-weight and stiffness-to-weight properties. However, the use of composite materials is currently limited by high cost and long manufacturing time. The National Aeronautics and Space Administration (NASA) initiated the Hi-rate Composite Aircraft Manufacturing (HiCAM) project to investigate promising composite processing technologies with a goal of vastly improving composite commercial aircraft manufacturing rate (4-6x faster than current production rates). Laser assisted automated fiber placement (AFP) of thermoplastics is a key technology that could increase speed of composite manufacturing, but the technology has not been fully developed. In-situ consolidation AFP of thermoplastics (ICAT) could reduce time and cost even further by eliminating the time and equipment required for post-consolidation. In this work, the thermal response of laser heated ICAT was investigated using forward looking infrared (FLIR) and embedded thermocouples (TCs) to better understand fusion between layers (autohesion). Detailed explanation of the algorithm to combine FLIR and TC data will be presented. In addition, the effect of robot speed on time above melting temperature was quantified.

Laser Heating↗
NASA NTRS1993

Techno-economic requirements for automotive composites

New technology generally serves two main goals of the automotive industry: one is to enable vehicles to comply with various governmental regulations and the other is to provide a competitive edge in the market. The latter goal can either be served through improved manufacturing and design capabilities, such as computer aided design and computer aided manufacturing, or through improved product performance, such as anti-lock braking (ABS). Although safety features are sometimes customer driven, such as the increasing use of airbags and ABS, most are determined by regulations as outlined by the Federal Motor Vehicle Safety Standards (FMVSS). Other standards, set by the Environmental Protection Agency, determine acceptable levels of emissions and fuel consumption. State governments, such as in California, are also setting precedent standards, such as requiring manufacturers to offer zero-emission vehicles as a certain fraction of their sales in the state. The drive to apply new materials in the automobile stems from the need to reduce weight and improve fuel efficiency. Topics discussed include: new lightweight materials; types of automotive materials; automotive composite applications; the role for composite materials in automotive applications; advantages and disadvantages of composite materials; material substitution economics; economic perspective; production economics; and composite materials production economics.

Arnold, Scot↗
NASA NTRS1990

Composite structural armor for combat vehicle applications

Several projects that have demonstrated the advantages of using thick composite armor technology for structural applications in armored combat vehicles are discussed. The first involved composite cargo doors for the Marine Corps LVTP-7 amphibious landing vehicle. Another was a demonstration composite turret that offered a weight reduction of 15.5 percent. The advantages of this composite armor compared to metallic armors used for combat vehicle hull and turret applications are reduced weight at equal ballistic protection; reduced back armor spall; excellent corrosion resistance; reduced production costs by parts consolidation; and inherent thermal and acoustic insulative properties. Based on the encouraging results of these past programs, the Demonstration Composite Hull Program was started in September 1986. To demonstrate this composite armor technology, the Army's newest infantry fighting vehicle, the Bradley Fighting Vehicle (BFV), was selected as a model. A composite infantry fighting vehicle, designated the CIFV for this program, has been designed and fabricated and is currently undergoing a 6000 mile field endurance test. The CIFV demonstration vehicle uses the BFV engine, transmission, suspension, track and other equipment.

Haskell, William E., III↗