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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 19 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1979

Moisture diffusion parameter characteristics for epoxy composites and neat resins

The moisture absorption characteristics of two graphite/epoxy composites and their corresponding cured neat resins were studied in high humidity and water immersion environments at elevated temperatures. Moisture absorption parameters, such as equilibrium moisture content and diffusion coefficient derived from data taken on samples exposed to high humidity and water soak environments, were compared. Composite swelling in a water immersion environment was measured. Tensile strengths of cured neat resin were measured as a function of their equilibrium moisture content after exposure to different moisture environments. The effects of intermittent moderate tensile loads on the moisture absorption parameters of composite and cured neat resin samples were determined.

Long, E. R., Jr.↗
NASA NTRS1988

Mechanical properties of neat polymer matrix materials and their unidirectional carbon fiber-reinforced composites

The mechanical properties of two neat resin systems for use in carbon fiber epoxy composites were characterized. This included tensile and shear stiffness and strengths, coefficients of thermal and moisture expansion, and fracture toughness. Tests were conducted on specimens in the dry and moisture-saturated states, at temperatures of 23, 82 and 121 C. The neat resins tested were American Cyanamid 1806 and Union Carbide ERX-4901B(MPDA). Results were compared to previously tested neat resins. Four unidirectional carbon fiber reinforced composites were mechanically characterized. Axial and transverse tension and in-plane shear strengths and stiffness were measured, as well as transverse coefficients of thermal and moisture expansion. Tests were conducted on dry specimens only at 23 and 100 C. The materials tested were AS4/3502, AS6/5245-C, T300/BP907, and C6000/1806 unidirectional composites. Scanning electron microscopic examination of fracture surfaces was performed to permit the correlation of observed failure modes with the environmental test conditions.

Zimmerman, Richard S.↗
NASA NTRS1997

Near-Earth Asteroid Tracking (NEAT) Program

The discoveries of near-Earth asteroids (NEA's) and comets have increased enormously over the last 10-20 years. This is a consequence in large par; of the success of programs that have systematically searched for these objects. These programs have been motivated by the relationships of NEA's to terrestrial impacts, meteorites, comets, and their relative accessibility to spacecraft missions. This paper will review the long-term Palomar Planet Crossing Asteroid Survey (PCAS) a photographic program and the current Near-Earth Asteroid Tracking (NEAT) system NASA's new electronic detection program. The primary goal of NEAT is to discover and inventory near-Earth asteroids and comets, collectively called near-Earth objects or NEO's, larger than 1 km in size. Details of the NEAT system and program results are presented and discussed.

Helin, Eleanor F.↗
NASA NTRSDate not supplied

Impedance Measurements of Motor Drives and Supplies in NASA NEAT Facility

Many electrified aircraft configurations consist of a number of power components operating on the same shared electrical bus. Understanding the impedance performance of electrical loads and sources is key to understanding, and designing for, acceptable overall vehicle power quality and power system stability. This paper discusses impedance measurements made on the NASA Electric Aircraft Testbed (NEAT) Electrical Power System (EPS) at NASA Glenn Research Center. First, an overall discussion of the NEAT facility configuration during testing is presented. Then, details of the impedance measurement approach and the various testing configurations are discussed. Next, input impedance measurements at NEAT, including sources (DC supplies) and loads (multiple motor drives, electric machines, and resistive load banks, with long interconnecting cable leads), are performed under a number of conditions, and results, including load model comparisons and stability analysis, are presented and discussed.

electrified aircraft propulsion↗
NASA NTRSDate not supplied

Impedance Measurements of Motor Drives and Supplies in NASA NEAT Facility

Many electrified aircraft configurations consist of a number of power components operating on the same shared electrical bus. Understanding the impedance performance of electrical loads and sources is key to understanding, and designing for, acceptable overall vehicle power quality and power system stability. This paper discusses impedance measurements made on the NASA Electric Aircraft Testbed (NEAT) Electrical Power System (EPS) at NASA Glenn Research Center. First, an overall discussion of the NEAT facility configuration during testing is presented; then details of the impedance measurement approach and the various testing configurations are discussed. Next, input impedance measurements at NEAT, including sources (DC supplies) and loads (multiple motor drives, electric machines, and resistive load banks, with long interconnecting cable leads), are performed under a number of conditions, and results, including load model comparisons and stability analysis, are presented and discussed.

electrified aircraft propulsion↗
NASA NTRS1995

The NEAT Camera Project

The NEAT (Near Earth Asteroid Tracking) camera system consists of a camera head with a 6.3 cm square 4096 x 4096 pixel CCD, fast electronics, and a Sun Sparc 20 data and control computer with dual CPUs, 256 Mbytes of memory, and 36 Gbytes of hard disk. The system was designed for optimum use with an Air Force GEODSS (Ground-based Electro-Optical Deep Space Surveillance) telescope. The GEODSS telescopes have 1 m f/2.15 objectives of the Ritchey-Chretian type, designed originally for satellite tracking. Installation of NEAT began July 25 at the Air Force Facility on Haleakala, a 3000 m peak on Maui in Hawaii.

NEAT Camera↗
NASA NTRS1983

Dynamic-mechanical response of graphite/epoxy composite laminates and neat resin

Dynamic mechanical measurement results are presented for the case of carbon fiber-reinforced, epoxy matrix composite laminates subjected to loading perpendicular to the lamination plane, as well as for neat epoxy resin under the same conditions, where temperatures ranged between 20 and 200 C and deformation levels lie within the linear viscoelastic region. In-phase and out-of-phase stiffnesses are found to become superposed, forming master curves that cover a 12-decade frequency range. The application of a master curve scaling procedure shows that the in-phase stiffness has the same shape, and out-of-phase stiffness has the same dispersion, for all laminates irrespective of stacking sequence and are, in turn, nearly identical to those for the neat epoxy resin. An empirical function is found for the relaxation modulus which, when converted to a dynamic modulus, yields good overall agreement for both of the dynamic stiffness components as a function of frequency.

Yang, P.↗
NASA NTRS1984

Experimental and Theoretical Studies of Moisture and Temperature Effects on the Mechanical Properties of Graphite/Epoxy Laminates and Neat Resins

The properties of high performnce composites which are strongly dependent on the physical properties of the matrix resin were studied. Moisture adversely affect the properties of both neat epoxy resin and epoxy matrix composites. Inhomogeneous swelling as to the moisture degradation of mechanical properties, both in the neat resin and the composite. It is postulated that the postcuring process can change structure/moisture interactions and partially alleviate its adverse effects. The study is directed toward are understanding of the physical/mechanical/thermodynamic aspects of this problem.

Sternstein, S. S.↗
NASA NTRS1989

Mechanical properties of several neat polymer matrix materials and unidirectional carbon fiber-reinforced composites

The mechanical and physical properties of three neat matrix materials, i.e., PEEK (polyetheretherketone) thermoplastic, Hexcel F155 rubber-toughened epoxy and Hercules 8551-7 rubber-toughened epoxy, were experimentally determined. Twelve unidirectional carbon fiber composites, incorporating matrix materials characterized in this or earlier studies (with one exception; the PISO(sub 2)-TPI matrix itself was not characterized), were also tested. These composite systems included AS4/2220-1, AS4/2220-3, T500/R914, IM6/HX1504, T300/4901A (MDA), T700/4901A (MDA), T300/4901B (MPDA), T700/4901B (MPDA), APC2 (AS4/PEEK, ICI), APC2 (AS4/PEEK, Langley Research Center), AS4/8551-7, and AS4/PISO(sub 2)-TPI. For the neat matrix materials, the tensile, shear, fracture toughness, coefficient of thermal expansion, and coefficient of moisture expansion properties were measured as a function of both temperature and moisture content. For the unidirectional composites, axial and transverse tensile, longitudinal shear, coefficient of thermal expansion, and coefficient of moisture expansion properties were determined, at room temperature and 100 C.

Coguill, Scott L.↗
NASA NTRS2004

Bima Array Detections of HCN in Comets Linear (C/2002 T7) and Neat (C/2001 Q4)

We present interferometric detections of HCN in comets LINEAR (C/2002 T7) and NEAT (C/2001 Q4) with the Berkeley-Illinois-Maryland Association (BIMA) Array in its D-configuration cross-correlation mode. We detected the HCN J = 1 - 0 emission line in both comets. With a 25".4 x 20".3 synthesized beam around Comet LINEAR, we found a total beam averaged HCN column density (assuming a rotation temperature of 146 K) of < N(sub T) > = 2.1(11)x 10(sup 13) cm(exp -2), and a HCN production rate of Q(HCN)=2.8(15)x 10(sup 27) s(exp -1). With a 21".3 x 17".5 synthesized beam around Comet NEAT, we found a total beam averaged HCN column density (assuming a rotation temperature of 107 K) of < N(sub T) > = 5.7(30) x 10(sup l2) cm(exp -2), and a HCN production rate of Q(HCN)=8.3(44) x 10(sup 26) s(exp -l) giving a production rate of HCN relative to H2O of approximately 0.09(5)%. The production rates relative to H2O and spatial extent of HCN are similar to previous comet observations.

Friedel, D. N.↗
NASA NTRS2007

Compact Fuel-Cell System Would Consume Neat Methanol

In a proposed direct methanol fuel-cell electric-power-generating system, the fuel cells would consume neat methanol, in contradistinction to the dilute aqueous methanol solutions consumed in prior direct methanol fuel-cell systems. The design concept of the proposed fuel-cell system takes advantage of (1) electro-osmotic drag and diffusion processes to manage the flows of hydrogen and water between the anode and the cathode and (2) evaporative cooling for regulating temperature. The design concept provides for supplying enough water to the anodes to enable the use of neat methanol while ensuring conservation of water for the whole fuel-cell system.

Narayanan, Sekharipuram↗
NASA NTRS2011

NEAT: A Microarcsec Astrometric Telescope

NEAT, Nearby Exo-Earth Astrometric Telescope is a medium-small telescope ~ 1m in diameter that is designed to make ultra precise < 1 uas (microarcsec) astrometric measurements of nearby stars in a ~ 1hr observation. Four major error sources prevent normal space telescopes from obtaining accuracies close to 1 uas. Even with a small 1m telescope, photon noise is usually not a problem for the bright nearby target stars. But in general, the reference stars are much fainter. Typically a field of view of ~0.5 deg dia is needed to obtain enough bright reference stars. The NEAT concept uses a very simple but unusual design to avoid optically induced astrometric errors. The third source of error is the accuracy and stability of the focal plane. A 1uas error over a ~2000 arcsec field of view implies the focal plane is accurate or at least stable to 5 parts in 1010 over the lifetime of the mission (~5yrs). The 4th class of error has to do with our knowledge of the PSF and how that PSF is sampled by an imperfect detector. A Nyquist sampled focal plane would have > 2 pixels per ?/D, and centroiding to 1uas means centroiding to 10-5 pixels. This paper describes the mission concept, and an overview of the technology needed to perform 1uas astrometry with a small telescope, and how we overcome problems 1 and 2. A companion paper will describe the technical progress we've made in solving problems 3 and 4.

interferometry↗
NASA NTRS2011

NEAT: A Microarcsec Astrometric Telescope

NEAT, Nearby Exo-Earth Astrometric Telescope is a medium-small telescope (is) approximately 1m in diameter that is designed to make ultra precise (is) less than 1 uas (microarcsec) astrometric measurements of nearby stars in a (is) approximately 1hr observation. Four major error sources prevent normal space telescopes from obtaining accuracies close to 1 uas. Even with a small 1m telescope, photon noise is usually not a problem for the bright nearby target stars. But in general, the reference stars are much fainter. Typically a field of view of (is) approximately 0.5 deg dia is needed to obtain enough bright reference stars. The NEAT concept uses a very simple but unusual design to avoid optically induced astrometric errors. The third source of error is the accuracy and stability of the focal plane. A 1uas error over a (is) approximately 2000 arcsec field of view implies the focal plane is accurate or at least stable to 5 parts in 10(exp 10) over the lifetime of the mission ( (is) approximately 5yrs). The 4th class of error has to do with our knowledge of the PSF and how that PSF is sampled by an imperfect detector. A Nyquist sampled focal plane would have (is) greater than 2 pixels per lambda/D, and centroiding to 1uas means centroiding to 10-5 pixels. This paper describes the mission concept, and an overview of the technology needed to perform 1uas astrometry with a small telescope, and how we overcome problems 1 and 2. A companion paper will describe the technical progress we've made in solving problems 3 and 4.

Earth like planets↗
NASA NTRS2022

Liquid crystals of neat boron nitride nanotubes and their assembly into ordered macroscopic materials

Boron nitride nanotubes (BNNTs) have attracted attention for their predicted extraordinary properties; yet, challenges in synthesis and processing have stifled progress on macroscopic materials. Recent advances have led to the production of highly pure BNNTs. Here we report that neat BNNTs dissolve in chlorosulfonic acid (CSA) and form birefringent liquid crystal domains at concentrations above 170 ppmw. These tactoidal domains merge into millimeter- sized regions upon light sonication in capillaries. Cryogenic electron microscopy directly shows nematic alignment of BNNTs in solution. BNNT liquid crystals can be processed into aligned films and extruded into neat BNNT fibers. This study of nematic liquid crystals of BNNTs demonstrates their ability to form macroscopic materials to be used in high- performance applications.

Cedric J. Simonsen Ginestra↗
NASA NTRS1983

Process for Molding Nonreinforced (Neat) Resins

Void free moldings obtained for neat, condensation, thermosetting resins. Thermally and mechanically treat resin prior to molding to reduce amount of volatiles. With volatiles reduced molding temperature and pressure are applied in way to drive out remaining volatiles during molding.

Dickerson, G. E.↗
NASA NTRS1984

Investigation of Toughened Neat Resins and Their Relations to Advanced Composite Mechanical Properties

Four epoxies (Hercules 3502, Hercules 2220-1 and 2220-3, and Ciba-Geigy Fibredux 914 epoxy) were evaluated to judge their merits within the ACEE program and also to provide material property input for a micromechanics finite element program. A casting procedure was developed for the four matrix systems mentioned and mechanical properties were studied at three test temperatures and two moisture contents. A scanning electron microscope study was performed to catalogue fracture surfaces for the unreinforced (neat) epoxies. In addition, tension testing, shear testing, a limited amount of fracture toughness testing, and thermal expansion coefficient and moisture expansion coefficient testing were carried out. Mechanical material properties were generated for input into a micromechanics program and to characterize these four matrix systems.

R. S. Zimmerman↗