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Durable Joining Technology for Uniformly-Curved Composite Sandwich Structures

An insert improves distribution of load through the joint, increasing safety. Langley Research Center, Hampton, Virginia NASA’s next-generation launch vehicles will be enabled by high-performance composite materials and innovative manufacturing methods. As such, NASA uses adhesively bonded joints where possible instead of mechanically fastened (bolted) joints to design and manufacture structures. The adhesive joints typically are lighter and distribute loads more efficiently across an interface, while mechanically fastened joints are prone to stress concentrations around the bolts.

Posted in: Manufacturing & Prototyping, Briefs

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Ohmic Contact to N- and P-Type Silicon Carbide

Ohmic contact can be formed in one process step. John H. Glenn Research Center, Cleveland, Ohio Electrical ohmic contacts can be simultaneously formed on silicon carbide (SiC) semiconductors having donor and acceptor impurities (n- and p-type doping, respectively). This implies that such contacts can be formed on SiC layers in one process step during the fabrication of the semiconductor device. This also means that the multiple process steps for fabricating contacts onto n- and p-type surfaces, which is characteristic of the prior art, will be greatly reduced, thereby reducing time and cost, and increasing yield (more process steps and complexity increases chances for lower yields). Another significance of this invention is that this scheme can serve as a non-discriminatory, universal ohmic contact to both n- and p-type SiC, without compromising the reliability of the specific contact resistivity when operated at temperatures in excess of 600 °C.

Posted in: Manufacturing & Prototyping, Briefs

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Flap Edge Noise Reduction Fins

This innovation has applications in aircraft leading edge slats and rotor tips for propulsion components on both aircraft and rotorcraft, as well as on wind turbines. Langley Research Center, Hampton, Virginia Aircraft noise is a significant problem with both economic and public health implications, especially for communities near airports. As a result, increasingly stringent constraints are being placed on aircraft carriers worldwide to reduce this noise. The current disclosure focuses on airframe noise generated at or near the surface of the flap-side edge.

Posted in: Manufacturing & Prototyping, Briefs

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Advanced Composite Thrust Chambers for In-Space Propulsion

Marshall Space Flight Center, Alabama Radiation-cooled, bipropellant thrust chambers are being used for in-space propulsion. To increase the performance of radiation-cooled engines, improved chamber materials are needed that will allow higher operating conditions (pressure and temperature), better resistance to oxidation, and reduced mass. During this effort, an innovative composite thrust chamber is being developed that will incorporate advanced hafnium oxide and iridium liner techniques as well as replacing the expensive, high-density rhenium with a low-mass carbon-carbon (C–C) structural wall.

Posted in: Manufacturing & Prototyping, Briefs

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Integrally Woven Fiber Architecture for Composite Turbine Blades

John H. Glenn Research Center, Cleveland, Ohio Composite turbine blades are currently fabricated by laying up multiple layers of fibers in the form of either unidirectional prepregs or thin woven cloth. Composites formed in this manner have poor through-thickness strength. It is also difficult, if not impossible, to form trailing edges as thin as necessary for optimum engine performance.

Posted in: Manufacturing & Prototyping, Briefs, TSP

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Assembly and Packaging to Mass-Produce Carbon Nanotube Vacuum Microdevices and Circuits

An assembly process allows mixing and matching of different types of electrode and dielectric layers assembled in a stack to create multi-electrode vacuum devices. NASA’s Jet Propulsion Laboratory, Pasadena, California Field-emission electron sources using carbon nanotubes (CNTs) are being targeted for low-power vacuum microelectronic applications for harsh-environment operation (high temperature, pressure, and corrosive atmosphere). While CNTs have demonstrated excellent properties in terms of low threshold field, low-power operation, and high-current densities, one of the problems that has persisted for vacuum electronic applications is the low yield of multi-electrode vacuum devices such as diodes, triodes, tetrodes, pentodes, etc.

Posted in: Manufacturing & Prototyping, Briefs, TSP

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Full-Cell Evaluation/Screening Technique for New Battery Chemistries

A full-cell configuration with a limited electrolyte in the cell is used to reflect the actual cell build conditions. John H. Glenn Research Center, Cleveland, Ohio A quick and cost-effective evaluation/screening technique for new battery chemistries was developed that integrates the individual advanced cell component in a full-cell format to identify the critical issues, such as cell component interaction and compatibility before proceeding to commercial production. To make the assessment more practical, a unique way of introducing limited electrolyte was developed. This technique enabled fast and low-cost screening to address any potential issues.

Posted in: Manufacturing & Prototyping, Briefs, TSP

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