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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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NASA NTRS1992

Application of composite materials to impact-insensitive munitions

An approach is outlined for developing bullet-impact-insensitive munitions based on composite materials that provide rapid venting of the rocket-motor case. Impact experiments are conducted with test specimens of hybrid laminates of graphite/epoxy and epoxy reinforcing with woven glass fibers. The dynamic strain response and initial impact force are measured with strain gauges, and perforation damage is examined in the plates. The results show that impact damage can be designed by means of parametric variations of the fiber, matrix, and ply orientations. It is suggested that rocket-motor cases can be designed with composite materials to provide rapid venting during the failure mode. The experimental ballistic testing performed provides data that can be used comparatively with analytical data on composite materials.

Neradka, Vincent F.↗

NASA NTRS2000

Disuse bone loss in hindquarter suspended rats: partial weightbearing, exercise and ibandronate treatment as countermeasures

The purpose of this study was to evaluate potential countermeasures for bone loss during long-term space missions in the hindquarter suspended rat, including partial weight bearing (surrogate for artificial gravity) episodic full weight bearing (2 hour/day full weight bearing) and treatment with the third generation bisphosphonate ibandronate (Roche). Graded mechanical loading was studied by housing the animals on a novel servo controlled force plate system which permitted the titration of mechanical force at varying frequency and amplitude and different levels of weight bearing. The force plate, which forms the cage floor, is a glass platform supported by an 18" diameter speaker cone filled with expanding polyurethane foam. An infrared optical sensor attached to the speaker cone yields a voltage linearly related to vertical displacement of the glass platform. The dynamic force on the paw was computed as a product of the apparent mass of the animal on the platform at rest and the acceleration of the platform determined from the second derivative of the optical sensor output. The mass of the animal on the platform was varied by adjusting tension on the tether suspending the animal. Mechanical impact loading was titrated with the force plate resonating at different frequencies, including 3 Hz and 16 Hz.

Non-NASA Center↗

NASA NTRS1986

Model system for studies of microbial dynamics at exuding surfaces such as the rhizosphere

An autoclavable all-glass system for studying microbial dynamics at permeable surfaces is described. Standard hydrophobic or hydrophilic membranes (46-mm diameter) of various pore sizes were supported on a glass frit through which nutrient solutions were pumped by a peristaltic pump. The pump provided a precisely controlled flow at speeds of 0.5 to 500 ml of defined or natural cell exudates per h, which passed through the membrane into a receiving vessel. The construction allowed a choice of membranes, which could be modified. The system was tested with a bacterium, isolated from rape plant roots (Brassica napus L.), that was inoculated on a hydrophilic membrane filter and allowed to develop into a biofilm. A defined medium with a composition resembling that of natural rape root exudate was pumped through the membrane at 0.5 ml/h. Scanning electron microscopic examinations indicated that the inoculum formed microcolonies embedded in exopolymers evenly distributed over the membrane surface. The lipid composition and content of poly-beta-hydroxybutyrate in free-living and adhered cells were determined by gas chromatography. The bacterial consumption of amino acids in the exudate was also studied.

NASA Discipline Number 61-10↗

NASA NTRS1985

Experimental Ecosystems Sealed in Glass

Report describes investigation of dynamics of microbial ecosystems sealed in 1-liter flasks and exposed to Sunlight or artifical light for extended periods. Many organisms survived more than 15 years. Such systems have primary productivity and quantum efficiencies comparable to estimates for Earth's ecosystems.

Hanson, J. A.↗

NASA NTRS1986

Effect of loading rate on dynamic fracture of reaction bonded silicon nitride

Wedge-loaded, modified tapered double cantilever beam (WL-MTDCB) specimens under impact loading were used to determine the room temperature dynamic fracture response of reaction bonded silicon nitride (RBSN). The crack extension history, with the exception of the terminal phase, was similar to that obtained under static loading. Like its static counterpart, a distinct crack acceleration phase, which was not observed in dynamic fracture of steel and brittle polymers, was noted. Unlike its static counterpart, the crack continued to propagate at nearly its terminal velocity under a low dynamic stress intensity factor during the terminal phase of crack propagation. These and previously obtained results for glass and RBSN show that dynamic crack arrest under a positive dynamic stress intensity factor is unlikely in static and impact loaded structural ceramics.

Liaw, B. M.↗

NASA NTRS1985

Lambda Point Equipment

A compilation of the active research tasks as of the end of the fiscal year 1984 of the Microgravity Science and Applications Program, NASA-Office of Space Science and Applications, involving several NASA centers and other organizations is presented. The purpose is to provide an overview of the program scope for managers and scientists in industry, university, and government communities. An introductory description of the program, strategy and overall goal; identification of the organizational structures and people involved; and a description of each research task, together with a list of recent publications is presented. The tasks are grouped into six categories: Electronic Materials; Solidification of Metals, Alloys, and Composites; Fluid Dynamics and Transports; Biotechnology; Glasses and Ceramics; and Combustion.

Lipa, J. A.↗

NASA NTRS1985

Microgravity science and applications bibliography, 1985 revision

This edition of the Microgravity Science and Applications (MSA) Bibliography is a compilation of Government reports, contractor reports, conference proceedings, and journal articles dealing with flight experiments utilizing a low-gravity environment to elucidate and control various processes or with ground-based activities that provide supporting research. It encompasses literature published but not cited in the 1984 Revision and that literature which has been published in the past year. Subdivisions of the bibliography include six major categories: Electronic Materials; Metal, Alloys, and Composites; Fluid Dynamics and Transports; Biotechnology; Glass and Ceramics; and Combustion. Also included are publications from the European, Soviet, and Japanese MSA programs. In addition, there is a list of patents and appendices providing a compilation of anonymously authored collection of reports and a cross reference index.

Pentecost, E.↗

NASA NTRS1988

Microgravity science and applications bibliography, 1987 revision

This edition of the Microgravity Science and Applications (MSA) Bibliography is a compilation of Government reports, contractor reports, conference proceedings, and journal articles dealing with flight experiments utilizing a low gravity environment to elucidate and control various processes or with ground based activities that provide supporting research. It encompasses literature published but not cited in the 1984 Revision and literature which has been published in the past year. Subdivisions of the bibliography include six major categories: Electronic Materials; Metals, Alloys, and Composites; Fluid Dynamics and Transport; Biotechnology; Glass and Ceramics; and Combustion. Also included are publications from the European, Soviet, and Japanese MSA programs. In addition, there is a list of patents and appendices providing a compilation of an anonymously authored collection of reports and a cross reference index.

Source record↗

NASA NTRS1989

Microgravity science and applications bibliography, 1988 revision

The Microgravity Science and Applications (MSA) Bibliography is a compilation of government reports, contractor reports, conference proceedings, and journal articles dealing with flight experiments utilizing a low-gravity environment to elucidate and control various processes or with ground-based activities that provide supporting research. It encompasses literature published but not cited in the 1984 Revision and the literature which was published in the past year. Subdivisions of the bibliography include: electronic materials; metals, alloys, and composites; fluid dynamics and transports; biotechnology; glass and ceramics; and combustion. Also included are publications from the European, Soviet, and Japanese MSA programs. In addition, there is a list of patents and appendices providing a compilation of anonymously authored collections of reports and a cross reference index.

Source record↗

NASA NTRS1989

Microgravity science and applications: Apparatus and facilities

NASA support apparatus and facilities for microgravity research are summarized in fact sheets. The facilities are ground-based simulation environments for short-term experiments, and the shuttle orbiter environment for long duration experiments. The 17 items of the microgravitational experimental apparatus are described. Electronic materials, alloys, biotechnology, fluid dynamics and transport phenomena, glasses and ceramics, and combustion science are among the topics covered.

Source record↗

NASA NTRS1992

Spacelab J: Microgravity and life sciences

Spacelab J is a joint venture between NASA and the National Space Development Agency of Japan (NASDA). Using a Spacelab pressurized long module, 43 experiments will be performed in the areas of microgravity and life sciences. These experiments benefit from the microgravity environment available on an orbiting Shuttle. Removed from the effects of gravity, scientists will seek to observe processes and phenomena impossible to study on Earth, to develop new and more uniform mixtures, to study the effects of microgravity and the space environment on living organisms, and to explore the suitability of microgravity for certain types of research. Mission planning and an overview of the experiments to be performed are presented. Orbital research appears to hold many advantages for microgravity science investigations, which on this mission include electronic materials, metals and alloys, glasses and ceramics, fluid dynamics and transport phenomena, and biotechnology. Gravity-induced effects are eliminated in microgravity. This allows the investigations on Spacelab J to help scientists develop a better understanding of how these gravity-induced phenomena affect both processing and products on Earth and to observe subtle phenomena that are masked in gravity. The data and samples from these investigations will not only allow scientists to better understand the materials but also will lead to improvements in the methods used in future experiments. Life sciences research will collect data on human adaptation to the microgravity environment, investigate ways of assisting astronauts to readapt to normal gravity, explore the effects of microgravity and radiation on living organisms, and gather data on the fertilization and development of organisms in the absence of gravity. This research will improve crew comfort and safety on future missions while helping scientists to further understand the human body.

Source record↗

NASA NTRS2001

Longtime Durability of PMR-15 Matrix Polymer at 204, 260, 288, and 316 C

Isothermal weight loss studies at the Glenn (Lewis) Research Center were conducted at four temperatures (204, 260, 288, and 316 C) with specimens of varied geometric shapes to investigate the mechanisms involved in the thermal degradation of PMR-15. Both neat resin behavior and composite behaviors were studied. Two points of interest in these studies are the role(s) of oxygen in the mechanisms involved in the thermo-oxidative degradation of these composite materials and the dimensional changes that occur during their useable lifetime. Specimen dimensional changes and surface layer growth were measured and recorded. It was shown that physical and chemical changes take place as a function of time and location in PMR-15 neat resin and composites as aging takes place in air at elevated temperatures. These changes initiate at the outer surfaces of both materials and progress inward following the oxygen as it proceeds by diffusion into the central core of each material. Microstructural changes cause changes in density, material shrinkage (strains), glass transition temperature, dimension, dynamic shear modulus, and compression properties. These changes also occur slowly dividing the polymer material into two distinct parts: a visibly undamaged core section between two visibly damaged surface layers. The surface layer has a significant effect on compression properties of thinner specimens, but the visibly undamaged core material controls these properties for specimens having eight or more plies. It was demonstrated that there are three different mechanisms involved in the degradation of PMR-15 during aging at elevated temperatures. These are a weight gain, a small weight fraction bulk material weight loss, and a large mass fraction weight loss concentrated at the surface of the polymer or composite. At the higher temperatures (260 C and above), the surface loss predominates. Below 260 C, the surface loss and the bulk core loss become more equivalent. Between 175 and 260 C, the initial weight change is due to a weight gain mechanism with a visible lifetime that diminishes as the aging temperature increases.

Bowles, Kenneth J.↗

NASA NTRS1989

Dynamic stress intensity factors of brittle materials

A new hybrid experimental-numerical procedure was used to characterize dynamic fracture response of structural ceramics at elevated temperature. The dynamic stress intensity factor (SIF) versus crack velocity relations of glass and reaction bonded silicon nitride (RBSN), are reviewed. The dynamic SIF versus crack velocity relations of alumina, TiB2-particulate/SiC-matrix composite and SiCw/Alumina-matrix composite are also presented. Available data indicated that dynamic arrest SIF was not observed in glass and monolithic ceramics, and suggested that further studies be conducted to resolve the existence or lack of existence of a dynamic arrest SIF in ceramic matrix composites.

Kobayashi, Albert S.↗

NASA NTRSDate not supplied

Verification of the Generalized Aerospace Simulation in Simulink

NASA uses six-degrees-of-freedom (6-DOF) simulations tools to design, test, develop Guidance Navigation and Control (GN&C) software, and certify vehicle performance prior to flight. Therefore, it is critical that the 6-DOF tools used for vehicle design and certification are validated. The focus of this work is the validation of the NASA Marshall Space Flight Center 6-DOF “GeneraLized Aerospace Simulation in Simulink” (GLASS) framework tool. The GLASS tool framework is currently used to support NASA GN&C insight for the Human Landing System (HLS) project, simulating vehicle dynamics during lunar descent and ascent. The GLASS framework utilizes the off-the-shelf Mathworks (R) Simscape (TM) Multibody (TM) toolbox to model vehicle multi-body dynamics. NASA’s Engineering and Safety Center (NESC) provides a set of 6-DOF simulation verification “check cases” that are available to any user needing to verify 6-DOF tools. The check cases contain seventeen atmospheric and twenty-six orbital test scenarios are provided to validate equations of motion, environmental models (e.g., atmosphere, gravitation, and geodesy) and tool propagators. This paper compares GLASS 6-DOF simulation results against the NESC check cases’ results via simulation-to-simulation comparisons. The comparison demonstrates that GLASS simulation results are “in family” with the outputs of the applicable NASA NESC check-cases and verify the GLASS core framework dynamics and the implementation of the check case scenario models.

6-Dof↗

NASA NTRS1991

Viscoelastic properties of addition-cured polyimides used in high temperature polymer matrix composites

Viscoelastic properties of the addition cured polyimide, PMR-15, were studied using dynamic mechanical and stress relaxation tests. For temperatures below the glass transition temperature, T sub g, the dynamic mechanical properties measured using a temperature scan rate of 10 C/min were strongly affected by the presence of absorbed moisture in the resin. Dynamic mechanical properties measured as a function of time during an isothermal hold provided an indication of chemical changes occurring in the resin. For temperatures above (T sub g + 20 C), the storage modulus increased continuously as a function of time indicating that additional crosslinking is occurring in the resin. Because of these changes in chemical structures, the stress relaxation modulus could not be measured over any useful time interval for temperatures above T sub g. For temperatures below T sub g, dynamic mechanical properties appeared to be unaffected by chemical changes for times exceeding 1 hr. Since the duration of the stress relaxation tests was less than 1 hr, the stress relaxation modulus could be measured. As long as the moisture content of the resin was less than 2 pct, stress relaxation curves measured at different temperatures could be superimposed using horizontal shifts along the log(time) axis with only small shifts along the vertical axis.

Roberts, Gary D↗

NASA NTRS1984

Orbiting dynamic compression laboratory

In order to examine the feasibility of carrying out dynamic compression experiments on a space station, the possibility of using explosive gun launchers is studied. The question of whether powders of a refractory metal (molybdenum) and a metallic glass could be well considered by dynamic compression is examined. In both cases extremely good bonds are obtained between grains of metal and metallic glass at 180 and 80 kb, respectively. When the oxide surface is reduced and the dynamic consolidation is carried out in vacuum, in the case of molybdenum, tensile tests of the recovered samples demonstrated beneficial ultimate tensile strengths.

Ahrens, T. J.↗

NASA NTRS1979

Radiation effects on the transmission of various optical glasses and epoxies

A recent study for the Dynamics Explorer satellite project involved the determination of the effects of gamma radiation (at 1.33 and 1.17 MeV) on the transmission of several optical glasses and epoxies to be used in the construction of interference filters. The samples studied included a control sample of pure fused silica, a cerium-stabilized radiation-resistant glass (Schott BK-7G), two pieces of quartz cemented with EPO-TEK 305 optical epoxy, two pieces of quartz cemented with APCO 5313 epoxy, a sample of Schott OG-590 glass, and a sample of Corning Corion glass. The transmission of different optical components was measured as a function of wavelength for several radiation doses.

Shetter, M. T.↗

NASA NTRS1984

Crystallization of heavy metal fluoride glasses

The kinetics of crystallization of a number of fluorozirconate glasses were studied using isothermal and dynamic differential scanning calorimetry and X-ray diffraction. The addition of the fluorides LiF, NaF, AlF3, LaF3 to a base glass composition of ZrF4-BaF2 reduced the tendency to crystallize, probably by modifying the viscosity-temperature relation. ZrF4-BaF2-LaF3-AlF3-NaF glass was the most stable against devitrification and perhaps is the best composition for optical fibers with low scattering loss. Some glasses first crystallize out into metastable beta-BaZr2F10 and beta-BaZrF6 phases, which transform into the most stable alpha-phases when heated to higher temperatures. The size of the crystallites was estimated to be about 600 A from X-ray diffraction.

Bansal, Narottam P.↗