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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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Quality control procedures include analyses on electrolyte, active materials, and separators for nickel cadmium cell materials. Tests range from the visual/mechanical inspection of cells to gas sampling, electrolyte extract, electrochemical tests, and physical measurements.
Procedures for conducting materials tests and structural analyses of aerospace components are presented as a part of the NASA technology utilization program. Some of the subjects discussed are as follows: (1) failures in cryogenic tank insulation, (2) friction characteristics of graphite and graphite-metal combinations, (3) evaluation of polymeric products in thermal-vacuum environment, (4) erosion of metals by multiple impacts with water, (5) mass loading effects on vibrated ring and shell structures, (6) nonlinear damping in structures, and (7) method for estimating reliability of randomly excited structures.
The study presents one method of mathematically modeling the effects of gravity-induced free convection upon the melting phenomena of a finite paraffin slab. The theoretical model is based on the numerical computer solution of the solid phase and liquid phase energy equations, coupled with an imposed ideal-viscous flow approximation. An implicit alternating-direction technique is used as the finite-difference approximation for the basic energy equations in the numerical solution. The theoretical predictions are compared to experimental data from an annular test cell, in which n-octadecane, C18H38, was used as the test material. The results show that the model is a good first approximation to the solution of solid-liquid phase change involving gravity-induced free convection.
The meteoroid penetration detectors on the Pioneer 10 spacecraft recorded 67 meteoroid penetrations through the 25-micron stainless steel test material while the spacecraft was between 1.0 and 5.1 AU. Ten of these penetrations occurred during the encounter with Jupiter. The cumulative spatial density of meteoroids with masses greater than 2 nanograms has been calculated from these data for interplanetary space and for the near-Jupiter space. The spatial density is found to be essentially constant in interplanetary space between 1 and 5 AU, approximately 1 meteoroid per cubic km, and 1-2 orders of magnitude greater near Jupiter. There was no increase in the spatial density of meteoroids in the asteroid belt and hence no evidence that there is a significant asteroidal component of 2-nanogram meteoroids. It is uncertain whether the meteoroids detected near Jupiter were in orbit about Jupiter or were gravitationally focused toward the planet from solar orbits.
Report presents flame-propagation rates and flammability ratings of 780 specimens of commercially available plastics, elastomers, coatings, fabrics, and other sheet materials. Test results are also given for over 1970 samples of most commonly used electrical harnesses, connectors, and potting compounds.
Results of an ongoing program set up to evaluate solar terrestrial photovoltaic power sources. The results of this program, which now includes a solar array encapsulant and materials test and a solar-powered buoy study, are updated, and the results of efforts to study the dynamic interaction of a solar photovoltaic array and a water electrolysis system coupled to produce hydrogen are reported for the first time.
The basic theory of CO2 gasdynamic lasers is discussed and related to the design of the Ames laser, which is described in detail. Results of the experimental calibration of the laser are reported and compared with theoretical predictions, and the agreement is excellent. Finally, several applications of the laser as a radiation source for materials testing, both with and without air flow, are described.
The effect of weave geometry on the onset of transition from laminar to turbulent flow around a sample of an orthogonally woven fine weave carbon-carbon material tested in an arc-jet is investigated. Seventeen post-test models which had undergone only partial transition around the circumference were examined as to location of turbulent regions relative to the weave axes. It was statistically shown that the weave axes had the lowest probability of being a position of initial transition onset. The probability generally increased with distance from a major axis, with some rays, notably the 45 deg rays, showing better transition resistance than the adjacent rays. The incidence of initial transition onset correlated well with the number of X or Y fibers that the flow passes over from stagnation point to the shoulder.
A photometer was developed and successfully operated to obtain photometric measurements on several flat, particulate surfaces of basalt for coplanar scattering geometries. The test materials were two size ranges each of two different basalts with significantly different albedos. The measurements include a range of phase angles from 30 to 80 degrees and were obtained by varying the angles of incidence and emission such that the phase angle remained constant. The data were used elsewhere in the verification of the Meador-Weaver photometric function and are presented here in the form of Minnaert plots. In this form the data offered the first support for the accuracy of the Meador-Weaver photometric function because of a deviation of the data from a straight line trend at larger departures from the mirror point geometry. This trend is predicted by the Meador-Weaver function but not by the Minnaert function. The failure of photometric data to support the Minnaert function was not evident in earlier measurements because of the restriction of planetary data to small departures from the mirror point geometry and to small values of the phase angle.
A simulation facility was established at the NASA-Lewis Research Center to determine the response of typical spacecraft materials to the geomagnetic substorm environment and to evaluate instrumentation that will be used to monitor spacecraft system response to this environment. Space environment conditions simulated included the thermal-vacuum conditions of space, solar simulation, geomagnetic substorm electron fluxes and energies, and the low energy plasma environment. Measurements for spacecraft material tests included sample currents, sample surface potentials, and the cumulative number of discharges. Discharge transients were measured by means of current probes and oscilloscopes and were verified by a photomultiplier.
Apparatus is used to test materials reaction to thermal shock by moving specimens between two chambers at high and low temperature extremes for specified number of cycles. Electrically motored system is completely automatic saving time and costs.
A simulation facility was established to determine the response of typical spacecraft materials to the geomagnetic substorm environment and to evaluate instrumentation that will be used to monitor spacecraft system response to this environment. Space environment conditions simulated include the thermal-vacuum conditions of space, solar simulation, geomagnetic substorm electron fluxes and energies, and the low energy plasma environment. Measurements for spacecraft material tests include sample currents, sample surface potentials, and the cumulative number of discharges. Discharge transients are measured by means of current probes and oscilloscopes and are verified by a photomultiplier. Details of this facility and typical operating procedures are presented.
The steady state contaminant load model based on shuttle equipment and material test programs, and on the current space station studies was revised. An emergency upset contaminant load model based on anticipated emergency upsets that could occur in an operational space station was defined. Control methods for the contaminants generated by the emergency upsets were established by test. Preliminary designs of both steady state and emergency contaminant control systems for the space station application are presented.
Asbestos reinforcing fiber in an automotive friction material was replaced by an experimental ingredient having better thermal stability, and the effects on wear and friction were studied. A friction materials test machine (SAE J661a) was used to determine friction and wear, under constant energy output conditions, as a function of temperature between 121 and 343 C (250 and 650 F). When potassium titanate fiber replaced one half of the asbestos in a standard commercial lining, with a 40 percent upward adjustment of phenolic resin content, wear above 204 C (400 F) was improved by 40% and friction by 30%. Tests on a full-scale inertial dynamometer supported the findings of the sample dynamometer tests. It was demonstrated that the potassium titanate fiber contributes directly to the improvement in wear and friction.
Report describes method of verification of solar space heating and hot-water systems using similarity comparison, mathematical analysis, inspections, and tests. Systems, subsystems, and components were tested for performance, durability, safety, and other factors. Tables and graphs compliment test materials.
Progress made by the Low-Cost Silicon Solar Array Project during the period January through March 1978 is reported. It includes task reports on silicon material processing, large-area silicon sheet development, encapsulation materials testing and development, project engineering and operations, and manufacturing techniques, plus the steps taken to integrate these efforts.
Topics discussed include silicon material processing; large-area silicon sheet development; encapsulation materials testing and development; project engineering and operations activities, and manufacturing techniques. The steps taken to integrate these efforts, are described.
Inexpensive, cosine-corrected radiometer measures ultraviolet radiation. In field use, instrument tests materials for effects of ultraviolet exposure and studies solar-cell degradation. It consists of cup-shaped diaphragm and diffusing dome for corrected response, two filters that select wavelength range, and silicon solar cell. Filters control response within passband of 300 to 400 nm.