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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 865 records · Page 48
All sourcesNASA NTRSDOE OSTI
NASA NTRS1992

The Canadian Space Agency, Space Station, Strategic Technologies for Automation and Robotics Program technology development activity in protection of materials from the low Earth orbit space environment

The Strategic Technologies in Automation and Robotics (STEAR) program is managing a number of development contracts to improve the protection of spacecraft materials from the Low Earth Orbit (LEO) space environment. The project is structured in two phases over a 3 to 4 year period with a budget of 3 to 4 million dollars. Phase 1 is designed to demonstrate the technical feasibility and commercial potential of a coating/substrate system and its associated application process. The objective is to demonstrate a prototype fabrication capability using a full scale component of a commercially viable process for the protection of materials and surface finishes from the LEO space environment, and to demonstrate compliance with a set of performance requirements. Only phase 1 will be discussed in this paper.

Francoeur, J. R.↗
NASA NTRS1992

Development of a truss joint for robotic assembly of space structures

This report presents the results of a detailed study of mechanical fasteners which were designed to facilitate robotic assembly of structures. Design requirements for robotic structural assembly were developed, taking into account structural properties and overall system design, and four candidate fasteners were designed to meet them. These fasteners were built and evaluated in the laboratory, and the Hammer-Head joint was chosen as superior overall. It had a high reliability of fastening under misalignments of 2.54 mm (0.1 in) and 3 deg, the highest end fixity (2.18), the simplest end effector, an integral capture guide, good visual verification, and the lightest weight (782 g, 1.72 lb). The study found that a good design should incorporate chamfers sliding on chamfers, cylinders sliding on chamfers, and hard surface finishes on sliding surfaces. The study also comments on robot flexibility, sag, hysteresis, thermal expansion, and friction which were observed during the testing.

Parma, George F.↗
NASA NTRS1992

Lubricant evaluation of the alpha and beta joints, phase 2

A research study was conducted to evaluate dry film lubrication of long life space components such as the alpha and beta joints of the Space Station. The problem addressed in the report pertains to the longevity of sputtered MoS2 or ion plated lead films in a rolling contact environment. A special technique was devised for the experiments, which incorporated a coated ball cyclically loaded against a flat plate. At fixed intervals the surface of the coating was photographed at 100X magnification. By computer scanning the photographs, the rate of coating loss was determined. Experimental variables include load and surface finish of the plate. A theory was developed to analyze the state of stress between ball and flat. The stress condition in the ball apparatus was related to the state of stress under rolling contact conditions. Based on the experiments life appeared to decrease with increasing load and increasing surface roughness. An ion plated lead film gave better life than a sputtered MoS2 film. However, by keeping the interfacial shear stress at a low level, adequate coating life was achieved for either coating. For the lead film, the critical stress was about 0.19 GPa (28 ksi). The study dealt only with mechanical wear. Before a coating is selected for a critical space application, other factors such as reaction with atomic oxygen must also be considered.

Kannel, J. W.↗
NASA NTRS1991

Derivation of midinfrared (5-25 microns) optical constants of some silicates and palagonite

The 5-25 micron real and imaginary refraction indices are presented for palagonite and the silicates pyrophyllite, kaolinite, serpentine, montmorillonite, saponite, and orthopyroxene. Optical constants in the region of the H2O-bending fundamental near 6 microns are obtained for saponite, montmorillonite, and palagonite. It is established that, if a pellet of pure material can be polished to a mirror finish, the optical constants of such noncohesive materials as clays are easily derivable.

Roush, T.↗
NASA NTRS1992

Use of cobalt sulfide (black dye) anodize for thermal control of the Space Station Freedom airlock

This paper presents six thermal design options of the Space Station Freedom (SSF) airlock and shows the important role that exterior coatings had in minimizing heater power. Options included using anodized coatings separately or in combination, employing fans to circulate interior air, and using a solar shade that eliminates the adverse effect of degrading optical properties. The design that is most efficient, in terms of cost and minimum heater power, and that meets all temperature requirements, has a black anodized exterior finish and uses a maximum of 410 watts of heater power.

Saiz, John↗
NASA NTRS1992

Overview of the manufacturing sequence of the Advanced Solid Rocket Motor

The manufacturing sequence of NASA's new Advanced Solid Rocket Motor, developed as a replacement of the Space Shuttle's existing Redesigned Solid Rocket Motor, is overviewed. Special attention is given to the case preparation, the propellant mix/cast, the nondestructuve evaluation, the motor finishing, and the refurbishment. The fabrication sequences of the case, the nozzle, and the igniter are described.

Chapman, John S.↗
NASA NTRS1992

Thermal verification testing of commercial printed-circuit boards for spaceflight

A method developed to verify commercial printed-circuit boards for a Shuttle orbital flight is discussed. The test sequence is based on early fault detection, desire to test the final assembly, and integration with other verification testing. A component thermal screening test is performed first to force flaws in design, workmanship, parts, processes, and materials into observable failures. Temperature definition and vibration tests are performed next. Final assembly testing is performed to simulate the Shuttle flight. An abbreviated thermal screening test is performed as a check after the vibration test, and then a complete thermal operational test is performed. The final assembly test finishes up with a burn-in of 100 h of trouble-free operation. Verification is successful when all components and final assemblies have passed each test. This method was very successful in verifying that commercial printed-circuit boards will survive in the Shuttle environment.

Foster, William M., II↗
NASA NTRS1992

Supersonic and hypersonic quiet tunnel technology at NASA Langley

Quiet tunnel technology at NASA Langley is reviewed focusing on historical background, basic quiet tunnel concepts, design methodology, and significant results. Each of the NASA Langley quiet tunnels and recent flow quality results for a refurbished Mach 6 quiet nozzle are presented. It is concluded that high-speed quiet tunels should be viewed as a required adjunct to computational and experimental tools being developed to explore issues of instability and transition physics. The quiet tunnel technology can produce and maintain an adequately smooth nozzle finish, control settling chamber disturbances, and keep the facility clean and is capable of adequately measuring flow disturbances.

Wilkinson, S. P.↗
NASA NTRS1993

Pressurized Shell Molds For Metal-Matrix Composites

Balanced-pressure molds used to make parts in complex shapes from fiber-reinforced metal-matrix composite materials. In single step, molding process makes parts in nearly final shapes; only minor finishing needed. Because molding pressure same on inside and outside, mold does not have to be especially strong and can be made of cheap, nonstructural material like glass or graphite. Fibers do not have to be cut to conform to molds. Method produces parts with high content of continuous fibers. Parts stiff but light in weight, and coefficients of thermal expansion adjusted. Parts resistant to mechanical and thermal fatigue superior to similar parts made by prior fabrication methods.

Kashalikar, Uday K.↗
NASA NTRS1993

Generating Smooth Motions For Robotic Manipulators

In improved method for generating trajectory of robotic manipulator, each straight-line segment of trajectory composed of constant-velocity main portion sandwiched between smooth acceleration at start and smooth deceleration at finish. Algorithm implementing method computes velocity in each accelerating portion as sinusoidal function of position along line. This motion chosen for two reasons: closely approximates motion of human hand along straight-line trajectory, and provides very smooth transitions between constant-velocity portion and accelerated and decelerational end portions.

Bejczy, Antal K.↗
NASA NTRS1993

Eddy-Current Monitoring Of Composite Layups

Eddy-current-probe apparatus used to determine predominant orientations of fibers in fiber/matrix composite materials. Apparatus nondestructive, noninvasive means for monitoring composite prepregs and layups during fabrication to ensure predictable and repeatable mechanical properties of finished composite panels. Consists essentially of electromagnet coil wrapped around horseshoe-shaped powdered-iron or ferrite ore. Optionally, capacitor included in series or parallel with coil to form resonant circuit. Impedance monitor excites radio-frequency current in coil and measures impedance of probe circuit. Affected by whatever material placed near ends of core, where material intercepts alternating magnetic field excited in core by current in coil.

Fox, Robert L.↗
NASA NTRS1992

Changes in oxidation state of chromium during LDEF exposure

The solar collector used for the McDonnell-Douglas Cascade Variable Heat Pipe, Experiment A0076 (Michael Grote - Principal Investigator) was finished with black chromium plating as a thermal control coating. The coating is metallic for low emittance, and is finely microcrystalline to a dimension which yields its high absorptivity. An underplate of nickel was applied to the aluminum absorber plate in order to achieve optimal absorptance characteristics from the black chromium plate surface. Experiment A0076 was located at tray position F9, receiving a projected 8.7 x 10 exp 21 atomic oxygen atoms/sq cm and 11,200 ESH solar radiation. During retrieval, it was observed that the aluminized kapton thermal blankets covering most of the tray were severely eroded by atomic oxygen, and that a 'flap' of aluminum foil was overlaying a roughly triangular shaped portion of the absorber panel. The aluminum foil 'flap' was lost sometime between the Long Duration Exposure Facility (LDEF) retrieval and deintegration. At deintegration, the black chromium was observed to have discolored where it had been covered by the foil 'flap'. A summary of the investigation into the cause of the discoloration is presented.

Golden, Johnny L.↗
NASA NTRS1992

Static assignment of complex stochastic tasks using stochastic majorization

We consider the problem of statically assigning many tasks to a (smaller) system of homogeneous processors, where a task's structure is modeled as a branching process, and all tasks are assumed to have identical behavior. We show how the theory of majorization can be used to obtain a partial order among possible task assignments. Our results show that if the vector of numbers of tasks assigned to each processor under one mapping is majorized by that of another mapping, then the former mapping is better than the latter with respect to a large number of objective functions. In particular, we show how measurements of finishing time, resource utilization, and reliability are all captured by the theory. We also show how the theory may be applied to the problem of partitioning a pool of processors for distribution among parallelizable tasks.

Nicol, David↗
NASA NTRS1989

Tether deployment monitoring system, phase 2

An operational Tether Deployment Monitoring System (TEDEMS) was constructed that would show system functionality in a terrestrial environment. The principle function of the TEDEMS system is the launching and attachment of reflective targets onto the tether during its deployment. These targets would be tracked with a radar antenna that was pointed towards the targets by a positioning system. A spring powered launcher for the targets was designed and fabricated. An instrumentation platform and launcher were also developed. These modules are relatively heavy and will influence tether deployment scenarios, unless they are released with a velocity and trajectory closely matching that of the tether. Owing to the tracking range limitations encountered during field trails of the Radar system, final TEDEMS system integration was not completed. The major module not finished was the system control computer. The lack of this device prevented any subsystem testing or field trials to be conducted. Other items only partially complete were the instrumentation platform launcher and modules and the radar target launcher. The work completed and the tests performed suggest that the proposed system continues to be a feasible approach to tether monitoring, although additional effort is still necessary to increase the range at which modules can be detected. The equipment completed and tested, to the extent stated, is available to NASA for use on any future program that requires tether tracking capability.

Source record↗
NASA NTRS1992

The 1992 NASA/ASEE Summer Faculty Fellowship Program

This is the administrative report for the 1992 NASA/ASEE Summer Faculty Fellowship Program which was held at the George C. Marshall Space Flight Center (MSFC) for the 28th consecutive year. The nominal starting and finishing dates for the ten week program were June 1, 1992 through August 7, 1992. The program was sponsored by NASA Headquarters, Washington, D.C., and operated under the auspices of the American Society for Engineering Education (ASEE). The program was one of eight such programs at eight NASA centers sponsored and funded by NASA Headquarters. The basic objectives of the program are the following: (1) to further the professional knowledge of qualified engineering and science faculty members; (2) to stimulate an exchange of ideas between participants and NASA; (3) to enrich and refresh the research and teaching activities at the participants' institutions; and (4) to contribute to the research objectives of the NASA centers. The major activities of the 1992 program were the following: (1) recruitment, selection, and assignment of faculty fellows; (2) research performed by the participants in collaboration with the MSFC colleague; (3) a seminar and tour program aimed at providing information concerning activities at MSFC; (4) an activities program of a social/non-technical nature aimed at providing the fellows and their families a means of learning about the MSFC/Huntsville area; and (5) preparation of a volume containing the written reports of the details of the research performed by each of the summer faculty. The success of the 1992 program activities in meeting the stated objectives was measured through questionnaires, which were filled out by participants and their MSFC colleagues. The following sections describe the major activities in more detail and the results of the questionnaires are summarized showing that the 1992 program was highly successful. This year's program also included 19 participants in the Summer Teacher Enrichment Program (STEP) which is comprised of middle school and high school math and science teachers.

Source record↗
NASA NTRS1992

Research in robust control for hypersonic vehicles

During the first reporting period research concentrated on finishing the modeling work required for a representative model of a scramjet propulsion system for hypersonic vehicles. An existing hypersonic propulsion code was adjusted to the winged-cone configuration. In this process the complete force and moment calculation was revised. The advantageous feature of the code to account for angle of attack variations was then used to compute the thrust, lift, and pitching moment contributions of the propulsion system not only for various Mach numbers and fuel equivalence ratios, but also for different angles of attack.

Calise, A. J.↗
NASA NTRS1993

A macro-micro robot for precise force applications

This paper describes an 8 degree-of-freedom macro-micro robot capable of performing tasks which require accurate force control. Applications such as polishing, finishing, grinding, deburring, and cleaning are a few examples of tasks which need this capability. Currently these tasks are either performed manually or with dedicated machinery because of the lack of a flexible and cost effective tool, such as a programmable force-controlled robot. The basic design and control of the macro-micro robot is described in this paper. A modular high-performance multiprocessor control system was designed to provide sufficient compute power for executing advanced control methods. An 8 degree of freedom macro-micro mechanism was constructed to enable accurate tip forces. Control algorithms based on the impedance control method were derived, coded, and load balanced for maximum execution speed on the multiprocessor system.

Marzwell, Neville I.↗
NASA NTRS1993

A new technology for manufacturing scheduling derived from space system operations

A new technology for producing finite capacity schedules has been developed in response to complex requirements for operating space systems such as the Space Shuttle, the Space Station, and the Deep Space Network for telecommunications. This technology has proven its effectiveness in manufacturing environments where popular scheduling techniques associated with Materials Resources Planning (MRPII) and with factory simulation are not adequate for shop-floor work planning and control. The technology has three components. The first is a set of data structures that accommodate an extremely general description of a factory's resources, its manufacturing activities, and the constraints imposed by the environment. The second component is a language and set of software utilities that enable a rapid synthesis of functional capabilities. The third component is an algorithmic architecture called the Five Ruleset Model which accommodates the unique needs of each factory. Using the new technology, systems can model activities that generate, consume, and/or obligate resources. This allows work-in-process (WIP) to be generated and used; it permits constraints to be imposed or intermediate as well as finished goods inventories. It is also possible to match as closely as possible both the current factory state and future conditions such as promise dates. Schedule revisions can be accommodated without impacting the entire production schedule. Applications have been successful in both discrete and process manufacturing environments. The availability of a high-quality finite capacity production planning capability enhances the data management capabilities of MRP II systems. These schedules can be integrated with shop-floor data collection systems and accounting systems. Using the new technology, semi-custom systems can be developed at costs that are comparable to products that do not have equivalent functional capabilities and/or extensibility.

Hornstein, R. S.↗