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Inkjet-Assisted Creation of Self-Healing Layers Between Composite Plies

Inkjet printing provides the ability to rapidly transfer this technology into a prepreg manufacturing process. University of Sheffield, United Kingdom A self-healing advanced composite system was designed and optimized using minimum self-healing (SH) agent (~0.02%) deposited in microscopically ordered arrays through inkjet printing, to arrest cracks along interfaces between plies (see figure). The approach consisted of depositing thermoplastic, low-viscosity microdroplets with chemically and mechanically comparable properties to epoxy matrix in aerospace-grade composites onto fiber-reinforced epoxy prepregs before curing. The SH agents remained arrested and encapsulated between epoxy plies without direct contact with neighboring microdroplets. This ensured consistent integrity of the composite while preserving the SH capability.

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Multi-Species Turbulent Mixing Under Supercritical-Pressure Conditions

This mixing model under high-pressure conditions would be useful for automotive, gas turbine engine, and liquid rocket engine companies. NASA’s Jet Propulsion Laboratory, Pasadena, California A model describing supercritical-pressure, multi-species turbulent mixing has been developed to simulate situations prevailing in diesel, gas turbine, and HCCI (homogeneous charge compression ignition) engines. It is also a situation occurring in atmospheric planetary science, such as the Venus atmosphere. Previously, there had been no model to describe this high-pressure mixing under turbulent conditions.

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A Model of Reduced Oxidation Kinetics Using Constituents and Species

The advantage of such a simple model becomes increasingly significant with increasing carbon atoms of the fuel. NASA’s Jet Propulsion Laboratory, Pasadena, California Elementary-reaction chemical kinetics of hydrocarbon oxidation consists of hundreds to thousands of species and thousands of reactions. As such, it is impossible to use it in models and codes involving turbulence because computations are unfeasible due to lack of memory and computer speed. The solution is to reduce the elementary chemical kinetics to a much smaller set of representative reactions. A kinetic reduction has been shown to work very well for isooctane and its mixtures with n-pentane, iso-hexane, and n-heptane.

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Determining Radiation Shielding Capability of the Earth’s Atmosphere from FAA Radiation Data

An algorithm is used to determine how much material is needed to shield astronauts on their trip to Mars. The FAA, using its CARI-6 program, provides galactic cosmic radiation dosage rates for any location on the Earth from ground up to 60,000 ft (≈18,300 m). One way to protect astronauts from galactic cosmic radiation (GCR) on a Mars mission is to use material shielding. However, current radiation shielding code does not model shields thicker than about 100 to 200 gm/cm2, and it has been shown that this shield thickness is insufficient to provide protection for a trip to Mars. There is effort underway to extend the code to thicker shields, but there is a lack of experimental data to use to verify the code. The atmosphere represents a very thick and effective radiation shield, and that atmospheric radiation data might be used as a source of verification data.

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High-Efficiency, Easy-to-Manufacture Engineered Nanomaterials for Thermoelectric Applications

Materials can be produced in thin/thick film form while maintaining film quality and stoichiometric balance. Marshall Space Flight Center, Alabama Stated generally, reducing the dimensionality of bulk-scale thermoelectric (TE) materials is theoretically and practically understood to be a viable route for maintaining/increasing phonon scattering, and maintaining/increasing electrical conductivity — necessary conditions for improving thermoelectric merit. Solution deposition of thin, anisotropic films of nanoscale particles of known TE materials is a route toward obtaining such low-dimensional materials with increased TE merit.

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Refractory Open-Cell Foam Fuel Matrix for High-Efficiency Nuclear Thermal Propulsion

A fuel form for fission applications is functional at extremely high temperatures with minimal erosion or fission product losses. Marshall Space Flight Center, Alabama A tricarbide foam fuel material has been developed that can operate at temperatures near 3,000 °C, without substantial hydrogen erosion, while providing highly efficient heat transfer to the coolant or propellant. A tricarbide foam fuel matrix of zirconium carbide (ZrC), niobium carbide (NbC), and uranium carbide (UC) has been successfully deposited and hydrogen tested. It shows that high-temperature, high-porosity foams can be produced that resist hydrogen corrosion and prevent the diffusion of fission products from the matrix. Chemical vapor deposition (CVD) technology was applied to nuclear materials systems that may be used in thermal propulsion and very high-temperature gas reactors.

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Hydrazine Absorbent/Detoxification Pad

This hydrazine-degrading pad has applications in hazardous-material emergency response situations. Lyndon B. Johnson Space Center, Houston, Texas A new chemistry was developed for existing hydrazine absorbent/detoxification pads. Enhancements include faster reaction rates, weight reduction, a color change that indicates spill occurrence, and another color change that indicates successful hydrazine degradation. The previous spill control pad, using copper oxide on the silica gel substrate as the reactant, affected only 50 percent degradation of hydrazine after 9 hours. The new prototypes have been found to degrade hydrazine from 95 to 99.9 percent in only 5 minutes, and to below detection limits within 90 minutes.

Posted in: Briefs, TSP

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