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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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Mechanical properties in flexure and shear of resin/glass fiber laminates at various times, temperatures and pressure exposures, postulating degradation mechanism
Quantum mechanical theory of thermal unimolecular breakdown kinetics of activated molecule in inert host gas based on Lindemann-Hinshelwood mechanism
Conference on mechanical engineering aspects of satellite systems - dynamic structural analyses and developments of control mechanisms, design specifications, and equipment components
Thermochemical and mechanical ablation mechanisms for Apollo heat shield material, comparing surface thermochemistry computer program and arc plasma tunnel data
Hydrogen embrittlement mechanism in steel based on modified pressure theory, discussing crack propagation mechanisms and stress corrosion cracking
Aerospace mechanisms conference including spacecraft booms, antennas, design, and power supplies, and mechanical devices operated in planetary environments
Book on celestial mechanics covering perturbation methods, two body problems, astronomical coordinates, orbital mechanics, satellite rotation, gravitational effects, etc
Ni-Ni Nb eutectic composite, investigating monotonic mechanical response, deformation and fracture mechanisms
Two cylindrical shutter mechanisms having fixed outer sleeves and rotating inner sleeves use single stepping motor and Geneva mechanism to sequentially move optical components into path of ultraviolet monochromator for output control to photomultiplier. Photometric and wavelength calibration sources insure shutter positions according to operational phases.
Conference of structural design principles and mechanical engineering methods for aerospace mechanisms used in orbital and space flights
The mechanical properties are presented of solution treated and age hardened A-286 corrosion resistant steel bar stock. Material solution treated at 899 C or 982 C, each followed by an age hardening treatment of 718 C, was evaluated. Test specimens manufactured from 1.50 inch (3.81 cm) diameter bar stock were tested at temperatures from +649 C to -253 C. The test data indicated excellent tensile, yield, elongation and reduction-in-area properties at all testing temperatures for both solution treated and aged materials. Cryogenic temperature notched tensile, impact, and shear tests indicated excellent notch strength, ductility, and shear values. There was very little difference in the mechanical properties of the two solution treated and aged materials. The only exception was that the 962 C solution treated and aged material had superior stress rupture properties at 649 C.
The mechanical properties of bare ZM-21 magnesium alloy flat tensile specimens were determined for test temperatures of +400 F, +300 F, +200 F, +80 F, 0 F, -100 F, -200 F, and -320 F. The ultimate tensile and yield strengths of the material increased with decreasing temperature with a corresponding reduction in elongation values. Stress corrosion tests performed under: (1) MSFC atmospheric conditions; (2) 95% relative humidity; and (3) submerged in 100 ppm chloride solution for 8 weeks indicated that the alloy is not susceptible to stress corrosion. The corrosion tests indicated that the material is susceptible to attack by crevice corrosion in high humidity and chemical type attack by chloride solution. Atmospheric conditions at MSFC did not produce any adverse effects on the material, probably due to the rapid formation of a protective oxide coating. In both the mechanical properties and the stress corrosion evaluations the test specimens which were cut transverse to the rolling direction had superior properties when compared to the longitudinal properties.
The Apollo 15 soil-mechanics experiment has offered greater opportunity for study of the mechanical properties of the lunar soil than previous missions, not only because of the extended lunar-surface stay time and enhanced mobility provided by the lunar roving vehicle (rover), but also because four new data sources were available for the first time. These sources were: (1) the self-recording penetrometer (SRP), (2) new, larger diameter, thin-walled core tubes, (3) the rover, and (4) the Apollo lunar-surface drill (ALSD). These data sources have provided the best bases for quantitative analyses thus far available in the Apollo Program.
The mechanism by which small quantities of dissolved tin, sodium, and lithium lower the rate of evaporation of mercury in vacuum is determined. An apparatus was built in which dilute amalgams could be prepared and studied in an oxygen-free environment before being exposed to oxygen under controlled conditions. The apparatus was able to maintain a pressure of less than 1.3 x 0.000001 N/sqm (10 to the minus 8th power torr) of gases and vapors other than mercury and less than 1.3 x 10 to the minus 8th N/sq m (10 to the minus 10th power torr) partial pressure of oxygen; also, it provided for mechanical sweeping of the liquid metal surfaces in the vacuum environment. The rates of evaporation of pure mercury and of dilute amalgams of tin (52 ppm), sodium (229 ppm), and lithium (165 ppm) were determined at temperature between 25 and 55 C both before and after 70 minute exposures to an approximately 270 N/sq m (2 torr) pressure of oxygen. The rates of evaporation of the pure mercury and the amalgams as first prepared were similar but the rates for the amalgams were reduced by at least 80% at 25 C as a result of the exposure to oxygen. The effect of the oxygen treatment could be completely removed by sweeping the amalgam surfaces. It was concluded that the reduced rates of evaporation resulted from the formation of transparent, insoluble, oxide films on the amalgam surfaces.
A study of molybdenum and three dilute molybdenum-rhenium alloys was undertaken to determine the effects of rhenium on the low temperature ductility and other mechanical properties of molybdenum. Alloys containing 3.9, 5.9, and 7.7 atomic percent rhenium exhibited lower ductile-brittle transition temperatures than did the unalloyed molybdenum. The maximum improvement in the annealed condition was observed for molybdenum - 7.7 rhenium, which had a ductile-brittle transition temperature approximately 200 C (360 F) lower than that for unalloyed molybdenum. Rhenium additions also increased the low and high temperature tensile strengths and the high temperature creep strength of molybdenum. The mechanical behavior of dilute molybdenum-rhenium alloys is similar to that observed for dilute tungsten-rhenium alloys.
The symposium includes presentation of both succe88es and failures in the design and development of mechanisms for spacecraft. Emphasis is given to aerospace mechanisms which have been either flight qualified or light demonstrated. Questions by various attendees and answers by the authors are also included.
The mechanisms of the TV camera and surface sampler retrieved from the Surveyor 3 spacecraft during the Apollo 12 mission are discussed. Data are presented showing the performance of these mechanisms before and after operation for one lunar day and storage for 2-1/2 years on the surface of the moon. An analysis of the critical component materials is also given.
Materials, design considerations, and design details for textile mechanical elements used in aerospace vehicle parachute systems are briefly reviewed. Friction burns are noted as a major cause of parachute system failures. The friction burn hazard can be minimized by designing for predeployment and deployment sequence control with textile mechanical restraints. Two basic restraint designs (restraint loops and line ties) are discussed and various applications of the designs shown.