SEARCH · Engineering Papers

Results for “ROOM”

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.

SourceResearch connectionFrom yearThrough year

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,369 records · Page 76

All sources NASA NTRS DOE OSTI

NASA NTRS1988

Qualification of room-temperature-curing epoxy adhesives for spacecraft structural applications

An adhesive-bonding test program is being conducted in order to develop structural adhesives applicable to JPL spacecraft. A noteworthy application for such an adhesive will be JPL's Galileo mission, whose trajectory will involve the circumnavigation of the planet Venus prior to Jupiter rendezvous, and will accordingly require stringent temperature and radiation environment requirements. The baseline adhesive for the test program is the EA 934 room temperature-cure epoxy, which has been widely used as a 'space-qualified' material.

Carpenter, Alain↗

NASA NTRS1988

Room-temperature operation of a Co:MgF2 laser

A normal-mode, pulsed Co:MgF2 laser has been operated at room temperature for the first time. Continuous tuning from 1750 to 2500 nm with pulse energies up to 70 mJ and 46-percent slope efficiency was obtained with a 1338-nm Nd:YAG pump laser.

Welford, D.↗

NASA NTRS1989

2.07-micron CW diode-laser-pumped Tm,Ho:YLiF4 room-temperature

Continuous-wave action is obtained at 2.07 microns from a 2-mm-long Tm-sensitized Ho:YLiF4 crystal at room temperature when longitudinally pumped by a pair of diode-laser arrays. Laser output power at 300 K is 26 mW, with a 30-percent slope efficiency and a lasing threshold of 108 mW. A maximum output power of 187 mW is obtained from a 4-mm-long crystal at 77 K, with a 67 percent slope efficiency. A preliminary demonstration of cavity Q switching produced 165 microJ of pulse energy at a repetition rate of 100 Hz.

Hemmati, Hamid↗

NASA NTRS1989

Room temperature tensile ductility in polycrystalline B2 Ni-30Al-20Fe

A room-temperature tensile elongation of about 2.5 percent, where the only slip vector observed was the 100, has been determined for a double-extruded B2 Ni-30Al-20Fe alloy consisting of recrystallized equiaxed grains about 25 microns in diameter; these results suggest that 100-slip does not preclude limited ductility in polycrystalline B2 alloys in tension at low temperatures. A suppression of ordering through resort to rapid solidification, in other words, is not necessary for ductility, since the cast and as-extruded alloy presently examined is ordered.

Guha, Sumit↗

NASA NTRS1989

Threshold analysis of pulsed lasers with application to a room-temperature Co:MgF2 laser

Rate-equation calculations are used to model accurately the near-threshold behavior of a Co:MgF2 laser operating at room temperature. The results demonstrate the limitations of the conventional threshold analysis in cases of practical interest. This conclusion is applicable to pulsed solid-state lasers in general. The calculations, together with experimental data, are used to determine emission cross sections for the Co:MgF2 laser.

Harrison, James↗

NASA NTRS1989

An advanced telerobotic system for shuttle payload changeout room processing applications

To potentially alleviate the inherent difficulties in the ground processing of the Space Shuttle and its associated payloads, a teleoperated, semi-autonomous robotic processing system for the Payload Changeout Room (PCR) is now in the conceptual stages. The complete PCR robotic system as currently conceived is described and critical design issues and the required technologies are discussed.

Sklar, M.↗

NASA NTRS1989

Torsional and biaxial (tension-torsion) fatigue damage mechanisms in Waspaloy at room temperature

Strain controlled torsional and biaxial (tension-torsion) low cycle fatigue behavior of Waspaloy was studied at room temperature as a function of heat treatment. Biaxial tests were conducted under proportional and nonproportional cyclic conditions. The deformation behavior under these different cyclic conditions was evaluated by slip trace analysis. For this, a Schmidt-type factor was defined for multiaxial loading conditions, and it was shown that when the slip deformation is predominant, nonproportional cycles are more damaging than proportional or pure axial or torsional cycles. This was attributed to the fact that under nonproportional cyclic conditions, deformation was through multiple slip, as opposed to single slip for other loading conditions, which gave rise to increased hardening. The total life for a given test condition was found to be independent of heat treatment. This was interpreted as being due to the differences in the cycles to initiation and propagation of cracks.

Jayaraman, N.↗

NASA NTRS1989

Tribological reactions of perfluoroalkyl polyether oils with stainless steel under ultrahigh vacuum conditions at room temperature

The reaction between three types of commercial perfluoroalkyl polyether (PFPE) oils and stainless steel 440C was investigated experimentally during sliding under ultrahigh vacuum conditions at room temperature. It is found that the tribological reaction of PFPE is mainly affected by the activity of the mechanically formed fresh surfaces of metals rather than the heat generated at the sliding contacts. The fluorides formed on the wear track act as a boundary layer, reducing the friction coefficient.

Mori, Shigeyuki↗

NASA NTRS1989

Notch effects on room temperature tensile and bend properties of Ni3Al and Ni3Al+B

The notched mechanical properties of Ni3Al and Ni3Al+B prepared by powder metallurgy techniques have been determined in both tension and bending at room temperature. Tensile tests performed using double-notched specimens containing relatively blunt notches produced intergranular fracture in both Ni3Al and Ni3Al+B, with evidence of fracture initiating in an intergranular manner ahead of the blunt notch in both cases. Estimates of notched fracture toughness from bend tests and of local grain boundary fracture stress from the notched tensile tests suggest an increase in these values with boron addition.

Khadkikar, P. S.↗

NASA NTRS1990

Static compression of Ca(OH)2 at room temperature - Observations of amorphization and equation of state measurements to 10.7 GPa

X-ray diffraction measurements are reported for Ca(OH)2 portlandite as it is compressed to 37.6 GPa in the diamond cell at room temperature. Between 10.7 and 15.4 GPa crystalline Ca(OH)2 transforms to a glass, and on decompression the glass recrystallizes between 3.6 and 5.1 GPa. Below pressures of 10.7 GPa the elastic compression of crystalline Ca(OH)2 was measured. A finite strain analysis of these data shows that the isothermal bulk modulus and its pressure derivative are 37.8 + or - 1.8 GPa and 5.2 + or - 0.7 at zero pressure. The change in the unit cell dimensions indicates that the linear incompressibilities of Ca(OH)2 differ by a factor of three.

Meade, Charles↗

NASA NTRS1989

Room-temperature InGaAs detector arrays for 2.5 microns

This paper describes new alloy heterojunction detectors of In(.8)Ga(.2)As/InAs(.6)P(.4) which can detect light between 1.7 and 2.6 microns with 50 percent quantum efficiency and 5 mA/sq cm dark current (-1 V) density at room temperature. Wafer probe data showed that over 50 good contiguous 100 micron diameter devices (spaced 400 microns) could be made on a 25 x 30 mm wafer with overall yield above 93 percent. The ability to operate under -1 V reverse bias makes these devices ideally compatible with existing commercial multiplexer readouts.

Olsen, G. H.↗

NASA NTRS1990

Humidity-induced room-temperature decomposition of Au contacted indium phosphide

It has been found that Au-contacted InP is chemically unstable at room temperature in a humid ambient due to the leaching action of indium nitrate islands that continually remove In from the contact metallization and thus, in effect, from the Inp substrate. While similar appearing islands form on Au-contacted GaAs, that system appears to be stable since leaching of the group III element does not take place.

Fatemi, Navid S.↗

NASA NTRS1991

Spatial variations in ac susceptibility and microstructure for the YBa2Cu3O(7-x) superconductor and their correlation with room-temperature ultrasonic measurements

The spatial (within-sample) uniformity of superconducting behavior and microstructure in YBa2Cu3O(7-x) specimens over the pore fraction range of 0.10 to 0.25 was examined. The viability of using a room-temperature, nondestructive characterization method (ultrasonic velocity imaging) to predict spatial variability was determined. Spatial variations in superconductor properties were observed for specimens containing 0.10 pore fraction. An ultrasonic velocity image constructed from measurements at 1 mm increments across one such specimen revealed microstructural variation between edge and center locations that correlated with variations in alternating-current shielding and loss behavior. Optical quantitative image analysis on sample cross-sections revealed pore fraction to be the varying microstructural feature.

Roth, Don J.↗

NASA NTRS1991

DSS 13 phase 2 pedestal room microwave layout

The design and predicted performance is described of the microwave layout for three band operation of the beam waveguide antenna Deep Space Station 13. Three pedestal room microwave candidate layout designs were produced for simultaneous X/S and X/Ka band operation. One of the three designs was chosen based on given constraints, and for this design the microwave performance was estimated.

Cwik, T.↗

NASA NTRS1990

Exodus - Distributed artificial intelligence for Shuttle firing rooms

This paper describes the Expert System for Operations Distributed Users (EXODUS), a knowledge-based artificial intelligence system developed for the four Firing Rooms at the Kennedy Space Center. EXODUS is used by the Shuttle engineers and test conductors to monitor and control the sequence of tasks required for processing and launching Shuttle vehicles. In this paper, attention is given to the goals and the design of EXODUS, the operational requirements, and the extensibility of the technology.

Heard, Astrid E.↗

NASA NTRS1990

Mechanical characterization of unnotched SCS6/Ti-15-3 metal matrix composites at room temperature

The Ti-15-3 metal matrix composites containing silicon-carbide (SCS6) fibers, in five different lay-ups, have been tested at room temperature to determine static strengths and mechanical properties. Experimental data and predicted values of the laminate properties and strengths showed good correlation. The off-axis laminate plies (that is, 90 and 45 deg) suffered fiber/matrix interface failures at stress levels as low as 20 ksi, thus significantly affecting the mechanical properties of the laminate. Edge replicas were used to verify the fiber/matrix separations. Microscopic examinations determined that the fiber/matrix failures were occurring in the titanium/silicon reaction layer. Fatigue tests were performed on unnotched specimens to determine the number of cycles to failure versus cyclic stress level. It was found that the stress in the 0 deg fiber could be used to correlate the fatigue life of different laminates containing 0 deg plies.

Johnson, W. S.↗

NASA NTRS1990

Mercuric iodine room temperature gamma-ray detectors

high resolution mercuric iodide room temperature gamma-ray detectors have excellent potential as an essential component of space instruments to be used for high energy astrophysics. Mercuric iodide detectors are being developed both as photodetectors used in combination with scintillation crystals to detect gamma-rays, and as direct gamma-ray detectors. These detectors are highly radiation damage resistant. The list of applications includes gamma-ray burst detection, gamma-ray line astronomy, solar flare studies, and elemental analysis.

Patt, Bradley E.↗

NASA NTRS1991

Correlation of mechanical properties with metallurgical structure for 18Ni 200 grade maraging steel at room and cryogenic temperatures

An extensive metallurgical study is presented which is intended to explain variations in the mechanical properties of Ni18 200 grade maraging steel in various product forms and orientations. Fracture toughness and Charpy impact values are found to decrease with decreasing temperature and be dependent on product form, specimen orientation, and metallurgical condition. Fatigue crack growth rates are dependent on temperature only. Fractographic analysis reveals that the decrease in toughness at -170 C is not associated with cleavage-type fracture morphology. Those specimens exhibiting low fracture toughness at room temperature or -170 C are found to have a significantly larger number of titanium-rich particles associated with dimple formation on the fracture surface.

Wagner, J. A.↗