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  • Other Sources  (146)
  • MECHANICAL ENGINEERING  (146)
  • 1980-1984  (146)
  • 1981  (146)
  • 1
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    A clamp mechanism for deployable three-ton payloads (1981)
    In:  CASI
    Details
    Publication Date: 2006-01-16
    Description: The requirements, capabilities, and unique design features of the instrument payload subsystem payload clamp assembly (PCA) are presented. The PCA is designed to have the flexibility to accommodate a wide payload range varying from 0.5 m to 3 m in diameter and from 500 kg to 3000 kg mass. This is achieved by modular clamp design in connection with replaceable struts. The design features include clamping of payload in a statically determined way and actuation of clamp latches by means of single linear actuator via ropes. The vibration and TV environmental conditions for the mechanism are extremely severe. A structural and prototype model was built. Test results of the operating characteristic are presented. In addition, problems of tribology are highlighted.
    Keywords: MECHANICAL ENGINEERING
    Type: NASA. Marshall Space Flight Center The 15th Aerospace Mech. Symp.; p 375-390
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  • 2
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    An antenna pointing mechanism for large reflector antennas (1981)
    In:  CASI
    Details
    Publication Date: 2006-01-16
    Description: An antenna pointing mechanism for large reflector antennas on direct broadcasting communication satellites was built and tested. After listing the requirements and constraints for this equipment the model is described, and performance figures are given. Futhermore, results of the qualification level tests, including functional, vibrational, thermovacuum, and accelerated life tests are reported. These tests were completed successfully.
    Keywords: MECHANICAL ENGINEERING
    Type: NASA. Marshall Space Flight Center The 15th Aerospace Mech. Symp.; p 253-261
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  • 3
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    A drive unit for the instrument pointing system (1981)
    In:  CASI
    Details
    Publication Date: 2006-01-16
    Description: The requirements, capabilities, and unique design features of the instrument pointing system drive units (DU) are presented. The DU's are identical for all three gimbal axes (elevation, cross elevation, and azimuth) and provide alternating rotation of shaft versus the housing of + or - 180 deg. The design features include: two ball bearing cartridges using cemented carbide balls coated with TiC a layer; redundant brushless torque motors and resolvers; a load by-pass mechanism driven by a dc torque motor to off-load the bearings during ascent/descent, ground transportation, and to provide an emergency breaking capability; and cabling over each gimbal axis by means of cable follow-up consisting of 13 signal and 15 power flat band cable loops. Test results of disturbance torque characteristics are presented.
    Keywords: MECHANICAL ENGINEERING
    Type: NASA. Marshall Space Flight Center The 15th Aerospace Mech. Symp.; p 263-278
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  • 4
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    An antenna fine pointing mechanism (1981)
    In:  CASI
    Details
    Publication Date: 2006-01-16
    Description: SOFA, a device designed for the highly accurate 2 axis pointing of antenna or any feature installed on a spacecraft is described. The major characteristic of this system is complete freedom from friction and wear out, resulting in numerous advantages, such as outstanding precision, virtually endless service life, high simplicity, and reliability. The sizing method is described and performances are analyzed. The results from analogue simulations are presented. A functional model of the electrical and mechanical parts was built and subjected to on ground tests using a 2 axis platform simulating the spacecraft's motions. The results obtained are thoroughly in keeping with the predictions and simulations. Various possible applications of the SOFA system are mentioned.
    Keywords: MECHANICAL ENGINEERING
    Type: NASA. Marshall Space Flight Center The 15th Aerospace Mech. Symp.; p 235-252
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  • 5
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    A mechanical drive for retractable telescopic masts (1981)
    In:  CASI
    Details
    Publication Date: 2006-01-16
    Description: Test results on the mechanical drive have indicated that the system is capable of deploying a typical telescopic mast under ambient conditions. The design can be considered for a wide range of space applications since, in theory, there is no limit to the number of tubes that can be deployed. The mechanical system offers a number of advantages over a gas driven system, such as the ability to retract and also provide a significant mass saving.
    Keywords: MECHANICAL ENGINEERING
    Type: NASA. Marshall Space Flight Center The 15th Aerospace Mech. Symp.; p 205-217
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  • 6
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    Tribology experiment (1981)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: A two-dimensional concept for Spacelab rack 7 was developed to study the interaction of liquid lubricants and surfaces under static and dynamic conditions in a low-gravity environment fluid wetting and spreading experiments of a journal bearing experiments, and means to accurately measure and record the low-gravity environment during experimentation are planned. The wetting and spreading process of selected commercial lubricants on representative surface are to the observes in a near-zero gravity environment.
    Keywords: MECHANICAL ENGINEERING
    Type: NASA. Marshall Space Flight Center Spacecraft Dyn. as Related to Lab. Expt. in Space; p 58-60
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  • 7
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    The transfer of polytetrafluoroethylene studied by X-ray photoelectron spectroscopy (1981)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: A polytetrafluoroethylene (PTFE) sphere of radius 4.8 mm was rubbed against nickel and S-Monel at speeds from 0.94 to 94 mm/s and at loads from 0.19 to 3.9 N. The transfer film of PTFE on the metal was examined with X-ray photoelectron spectroscopy. In all cases the film was found to be indistinguishable from bulk PTFE. A trace of metal fluoride was observed whether the rubbing took place on oxidized or atomically clean metal. The film was of the order of a molecule thick for the entire range of loads and did not increase with repeated passes over the same rubbed area. An erratic increase in thickness at rubbing speeds above 10 mm/s was taken as evidence of random transfer of bulk material.
    Keywords: MECHANICAL ENGINEERING
    Type: Wear; 66; Feb. 16
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  • 8
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    Ball bearing lubrication: The elastohydrodynamics of elliptical contacts (1981)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: The history of ball bearings is examined, taking into account rollers and the wheel in the early civilizations, the development of early forms of rolling-element bearings in the classical civilizations, the Middle Ages, the Industrial Revolution, the emergence of the precision ball bearing, scientific studies of contact mechanics and rolling friction, and the past fifty years. An introduction to ball bearings is presented, and aspects of ball bearing mechanics are explored. Basic characteristics of lubrication are considered along with lubrication equations, the lubrication of rigid ellipsoidal solids, and elastohydrodynamic lubrication theory. Attention is given to the theoretical results for fully flooded elliptical hydrodynamic contacts, the theoretical results for starved elliptical contacts, experimental investigations, the elastohydrodynamics of elliptical contacts for materials of low elastic modulus, the film thickness for different regimes of fluid-film lubrication, and applications.
    Keywords: MECHANICAL ENGINEERING
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  • 9
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    Development of a polymetric grout for the hydrostatic bearing at DSS 14 (1981)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: Results of an investigation into the causes of the deterioration and premature failure of the grout under the hydrostatic bearing runner at DSS 14 are reported. Generic types of materials were screened and tested to find a grout material more resistive to the causes of grout failure. Emphasis was placed on the physical properties, strength, modulus of elasticity, and resistance to erosion and chemical attack by oil and unique requirements imposed by each material for mixing, placing, compacting, and cooling. The polymetric grout developed to replace the dry grout is described.
    Keywords: MECHANICAL ENGINEERING
    Type: The Telecommun. and Data Acquisition; p 115-148
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  • 10
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    Torque characteristics of a 122-centimeter butterfly valve with a hydro/pneumatic actuator (1981)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: Actuating torque data from field testing of a 122-centimeter (48 in.) butterfly valve with a hydro/pneumatic actuator is presented. The hydraulic cylinder functions as either a forward or a reverse brake. Its resistance torque increases when the valve speeds up and decreases when the valve slows down. A reduction of flow resistance in the hydraulic flow path from one end of the hydraulic cylinder to the other will effectively reduce the hydraulic resistance torque and hence increase the actuating torque. The sum of hydrodynamic and friction torques (combined resistance torque) of a butterfly valve is a function of valve opening time. An increase in the pneumatic actuating pressure will result in a decrease in both the combined resistance torque and the actuator opening torque; however, it does shorten the valve opening time. As the pneumatic pressure increases, the valve opening time for a given configuration approaches an asymptotical value.
    Keywords: MECHANICAL ENGINEERING
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  • 11
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    Hostile environmental conditions facing candidate alloys for the automotive Stirling engine (1981)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: The materials research program in support of the Automotive Stirling Engine Project focuses on the hot heater head of the engine including the heater head tubes, cylinders, and regenerator housings, which are considered to be the most critical components from a materials viewpoint. The specific areas of investigation in the program involve hydrogen permeability testing, doping of the hydrogen working fluid to reduce permeability rates, oxidation/corrosion studies, creep-rupture evaluation, and assessing effects of hydrogen environment on mechanical properties. Emphasis is placed on the materials challenges that result from the use of hydrogen as the working fluid. Previously announced in STAR as N81-26236
    Keywords: MECHANICAL ENGINEERING
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  • 12
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    Design aspects of a solar array drive for spot, with a high platform stability objective (1981)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: A solar array drive mechanism (MEGS) for the SPOT platform, which is a prototype of a multimission platform, is described. High-resolution cameras and other optical instruments are carried by the platform, requiring excellent platform stability in order to obtain high-quality pictures. Therefore, a severe requirement for the MEGS is the low level of disturbing torques it may generate considering the 0.6 times 10 to the minus 3 power deg/sec stability required. The mechanical design aspects aiming at reducing the mean friction torque, and therefore its fluctuations, are described as well as the method of compensation of the motor imperfections. It was concluded, however, that this is not sufficient to reach the stability requirement.
    Keywords: MECHANICAL ENGINEERING
    Type: NASA. Kennedy Space Center The 16th Aerospace Mech. Symp.; p 143-157
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  • 13
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    An extended model for determining dynamic loads in spur gearing (1981)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: In this study a large scale digitized approach is used for an uninterrupted static and dynamic analysis of spur gearing. An interactive method was developed to calculate directly the variable gear mesh stiffness as a function of transmitted load, gear profile errors, gear tooth deflections and gear hub torsional deformation, and position of contacting profile points. The developed methods are applicable to both the normal and high contact ratio gearing. Certain types of simulated sinusoidal profile errors and pitting can cause interruptions of the normal gear mesh stiffness function and, thus, increase the dynamic loads in gearing.
    Keywords: MECHANICAL ENGINEERING
    Type: ASME PAPER 80-C2/DET-90
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  • 14
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    Low thermal conductance rigidizer for reducing torsional oscillations in cryogenic Dewars (1981)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: A rigidizer, which provides greater rigidity against torsional oscillations, is highly resistant to radial motions, and has low thermal conductivity, has been developed to decrease vibrational levels affecting infrared detectors operated in cryostats (e.g., HD-3L Dewar) in aircraft such as NASA's Kuiper Airborne Observatory. The rigidizer is composed of two triangular elements and an intermediate support structure which joins them at the centers of their sides. The reentrant design provides a long heat path, while the triangular truss structure provides high rigidity in the horizontal plane. The structure is relatively compliant in the vertical direction, a desirable feature since the internal structure of the Dewar contracts as it cools. Rigidity in the vertical direction is provided by the neck tube. The support structure is quite compact. Several variants of the rigidizer have been fabricated, using flat sheets of G-10 fiberglass epoxy in thicknesses between 0.75-1.5 mm for the upper and lower truss assemblies, and either G-10 or stainless steel for the intermediate structure.
    Keywords: MECHANICAL ENGINEERING
    Type: Review of Scientific Instruments; 52; Mar. 198
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  • 15
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    Terminal guidance sensor system (1981)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: A system is described for guiding a claw to the proper distance and into the proper orientation in yaw and pitch, to engage a grappling fixture. The system includes four proximity sensors on the claw, that are arranged at corners of an imaginary square, which sense the distance to the top surface of the grappling fixture. If a pair of sensors at opposite corners of the square sense a different distance to the top surface of the grappling fixture, then it is known that the claw is rotated about a corresponding axis with respect to the plane of the grappling fixture.
    Keywords: MECHANICAL ENGINEERING
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  • 16
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    Method of cold welding using ion beam technology (1981)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: A method for cold welding metal joints is described. In order to remove the contamination layer on the surface of the metal, an ion beam generator is used in a vacuum environment. A gas, such as xenon or argon, is ionized and accelerated toward the metal surface. The beam of gas effectively sputters away the surface oxides and contamination layer so that clean underlying metal is exposed in the area to be welded. The use of this method allows cold welding with minimal deformation. Both similar and dissimilar metals can be cold welded with this method.
    Keywords: MECHANICAL ENGINEERING
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  • 17
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    Performance of jet- and inner-ring-lubricated 35 millimeter bore ball bearings operating to 2.5 million DN (1981)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Parametric tests were conducted with a 35 millimeter bore, angular contact ball bearing having a single outer land guided cage. Lubrication was achieved by flowing oil through axial grooves and radial holes machined in the inner ring of the bearing. Test conditions were a thrust load of 667 N (150 lb), shaft speeds from 48,000 to 72,000 rpm, and an oil inlet temperature of 394 K (250 F). Data from tests where the distribution of the total oil supplied to the inner ring was 50 percent for bearing lubrication and 50 percent for bearing inner ring cooling were compared with those where the distribution pattern was 25 percent lubrication and 75 percent cooling. Successful operation was experienced with both the 50-50 and 25-75 percent flow distribution patterns to 2.5 million DN. The 50-50 percent flow pattern provided the cooler bearing operation of the two inner ring lubricated bearings. The jet lubricated bearing had lower outer ring and higher inner ring temperatures than the inner ring lubricated bearings. Maximum power loss of 2.8 kW (3.7 hp) was experienced with the 25-75 percent flow distribution, and maximum percent cage slip of 7.0 occurred at 72,300 rpm with the 50-50 percent flow distribution.
    Keywords: MECHANICAL ENGINEERING
    Type: NASA-TP-1808 , E-515
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  • 18
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    Transient dynamic analysis of high-speed lightly loaded cylindrical roller bearings. 2: Computer program and results (1981)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: The governing differential equations of motion for a high speed cylindrical roller bearing are programmed for numerical solution and plotted output. This computer program has the capability of performing a two dimensional or three dimensional simulation. Two numerical solutions of the governing differential equations were obtained to simulate the motion of a roller bearing, one for the two dimensional equations of motion and one for the three dimensional equations of motion. Computer generated plots were obtained and present such data as roller/cage interaction forces, roller/race traction forces, roller/race relative slip velocities and cage angular speed over a nondimensional time equivalent to 1.2 revolutions of the inner race. Roller axial displacement, roller skew angle, and skew moment are also plotted for the three dimensional solution. The trajectory of the cage center is plotted for both the two dimensional and three dimensional solutions.
    Keywords: MECHANICAL ENGINEERING
    Type: NASA-CR-3335
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  • 19
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    History of ball bearings (1981)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: The familiar precision rolling-element bearings of the twentieth century are products of exacting technology and sophisticated science. Their very effectiveness and basic simplicity of form may discourage further interest in their history and development. Yet the full story covers a large portion of recorded history and surprising evidence of an early recognition of the advantages of rolling motion over sliding action and progress toward the development of rolling-element bearings. The development of rolling-element bearings is followed from the earliest civilizations to the end of the eighteenth century. The influence of general technological developments, particularly those concerned with the movement of large building blocks, road transportation, instruments, water-raising equipment, and windmills are discussed, together with the emergence of studies of the nature of rolling friction and the impact of economic factors. By 1800 the essential features of ball and rolling-element bearings had emerged and it only remained for precision manufacture and mass production to confirm the value of these fascinating machine elements.
    Keywords: MECHANICAL ENGINEERING
    Type: NASA-TM-81689 , E-209
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  • 20
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    Reciprocating engines (1981)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: An intake valve arrangement for positively controlling the opening and closing of the poppet valve in a hot gas cylinder in a hydrazine powered engine is described. The poppet valve is operated by the piston and gas pressure only. The poppet valve uses a pneumatic spring which holds the poppet valve against the piston while the valve is opened and closed. To accomplish this, a poppet valve is slidably mounted in a pneumatic spring chamber which reaches a pressure approaching the gas supply pressure and, during the opening of the valve, the spring chamber retains enough pressure to hold the poppet valve onto the piston. In addition, the bottom of the poppet valve can have a suction cup type configuration to hold the poppet valve on the piston during the down stroke.
    Keywords: MECHANICAL ENGINEERING
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  • 21
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    The 34-meter antenna drive control system (1981)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Detailed definitions of the baseline antenna drive and control/instrumentation equipment for 34 meter antennas included in Network Consolidation Program of the Deep Space Network are presented. The overall antenna control and monitor system and its interfaces with other higher level control and monitor equipment is described. Explicit descriptions of the antenna axis drive motors and motor controllers, the axis angle encoding systems, and miscellaneous antenna located components are presented, and related to system functional and performance requirements. Some potential alternates to the baseline system configuration are described and discussed.
    Keywords: MECHANICAL ENGINEERING
    Type: NASA-CR-164683 , WDL-TR9153 , JPL-9950584
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  • 22
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    Development of high-speed balancing technology (1981)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: An investigation into laser material removal showed that laser burns act in a manner typical of mechanical stress raisers causing a reduction in fatigue strength; the fatigue strength is lowered relative to the smooth specimen fatigue strength. Laser-burn zones were studied for four materials: Alloy Steel 4340, Stainless Steel 17-4 PH, Inconel 718, and Aluminum Alloy 6061-T6. Calculations were made of stress concentration factors K, for laser-burn grooves of each material type. A comparison was then made to experimentally determine the fatigue strength reduction factor. These calculations and comparisons indicated that, except for the 17-4 PH material, good agreement (a ratio of close to 1.0) existed between Kt and Kf. The performance of the 17-4 PH material has been attributed to early crack initiation due to the lower fatigue resistance of the soft, unaged laser-affected zone. Also covered in this report is the development, implementation, and testing of an influence coefficient approach to balancing a long, slender shaft under applied-torque conditions. Excellent correlation existed between the analytically predicted results and those data obtained from testing.
    Keywords: MECHANICAL ENGINEERING
    Type: NASA-CR-165314 , MTI-81TR8
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  • 23
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    Life analysis of multiroller planetary traction drive (1981)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: A contact fatigue life analysis was performed for a constant ratio, Nasvytis Multiroller Traction Drive. The analysis was based on the Lundberg-Palmgren method for rolling element bearing life prediction. Life adjustment factors for materials, processing, lubrication and traction were included. The 14.7 to 1 ratio drive consisted of a single stage planetary configuration with two rows of stepped planet rollers of five rollers per row, having a roller cluster diameter of approximately 0.21 m, a width of 0.06 m and a weight of 9 kg. Drive system 10 percent life ranged from 18,800 hours at 16.6 kW (22.2 hp) and 25,000 rpm sun roller speed, to 305 hours at maximum operating conditions of 149 kw (200 hp) and 75,000 rpm sun roller speed. The effect of roller diameter and roller center location on life were determined. It was found that an optimum life geometry exists.
    Keywords: MECHANICAL ENGINEERING
    Type: NASA-TP-1710 , AVRADCOM-TR-80-C-16 , E-484
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  • 24
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    Lubrication background (1981)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Surface topography, including the various physical methods of measuring surfaces, and the various lubrication regimes (hydrodynamic, elastohydrodynamic, boundary, and mixed) are discussed. The historical development of elastohydrodynamic lubrication is outlined. The major accomplishments in four periods, the pre-1950's, the 1950's, the 1960's, and the 1970's are presented.
    Keywords: MECHANICAL ENGINEERING
    Type: NASA-TM-81692 , E-209 , NAS 1.15:81692
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  • 25
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    Advanced Gas Turbine (AGT) powertrain system (1981)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: A 74.5 kW(100 hp) advanced automotive gas turbine engine is described. A design iteration to improve the weight and production cost associated with the original concept is discussed. Major rig tests included 15 hours of compressor testing to 80% design speed and the results are presented. Approximately 150 hours of cold flow testing showed duct loss to be less than the design goal. Combustor test results are presented for initial checkout tests. Turbine design and rig fabrication is discussed. From a materials study of six methods to fabricate rotors, two have been selected for further effort. A discussion of all six methods is given.
    Keywords: MECHANICAL ENGINEERING
    Type: NASA-CR-165346 , NAS 1.26:165346 , EDR-10578 , SATSR-2
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  • 26
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    A pad perturbation method for the dynamic coefficients of tilting-pad journal bearings (1981)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: A pad assembly method for analyzing tilting-pad bearings is presented. The method results in the complete coefficient matrix for a tilting-pad bearing; the matrix is independent of the pad inertia, the pitch frequency and the number of degrees of freedom of the pad. A pad assembly method is used because it allows the collection of more bearing data with less computer time than a brute force iterative procedure. The results given show the complete dynamical matrices for a five-pad tilting-pad bearing both including and ignoring the damping effects of the unloaded (top) pads. For a symmetrical tilting-pad bearing the reduced cross-coupling coefficients are zero when the moment of inertia of the pad is ignored.
    Keywords: MECHANICAL ENGINEERING
    Type: Wear; 72; Oct. 1
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  • 27
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    Reusable captive blind fastener (1981)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: A one piece reusable fastener capable of joining materials together from one side (blind backside) comprises a screw driven pin ending in a wedge-shaped expander cone. The cone cooperates within a slotted collar end which has a number of tangs on a cylindrical body. The fastener is set by inserting it through aligned holes in the workpieces to be joined. Turning the pin in one direction draws the cone into the collar, deforming the tangs radially outward to mate with tapered back-tapered hold in the workpiece, thus fastening the two pieces together. Reversing the direction of the pin withdraws the cone from the collar, and allows the tangs to resume their contracted configuration without withdrawing the fastener from the insertion hole. The fastener is capable of joining materials together from only one side with substantial strength in tension and shear over many resue attachment cycles, with no special operations on the main assembly parts other than the tapering of the back end of the insertion hole.
    Keywords: MECHANICAL ENGINEERING
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  • 28
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    A multi-purpose method for analysis of spur gear tooth loading (1981)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: A large digitized approach was developed for the static and dynamic load analysis of spur gearing. An iterative procedure was used to calculate directly the "variable-variable" gear mesh stiffness as a function of transmitted load, gear tooth profile errors, gear tooth deflections and gear hub torsional deformation, and position of contacting profile points. The developed approach can be used to analyze the loads, Hertz stresses, and PV for the normal and high contrast ratio gearing, presently the modeling is limited to the condition that for a given gear all teeth have identical spacing and profiles (with or without surface imperfections). Certain types of simulated sinusoidal profile errors and pitting can cause interruptions of the gear mesh stiffness function and, thus, increase the dynamic loads in spur gearing. In addition, a finite element stress and mesh subprogram was developed for future introduction into the main program for calculating the gear tooth bending stresses under dynamic loads.
    Keywords: MECHANICAL ENGINEERING
    Type: NASA-CR-165163
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  • 29
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    Electrical servo actuator bracket (1981)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: An electrical servo actuator is mounted on a support arm which is allowed to pivot on a bolt through a fixed mounting bracket. The actuator is pivotally connected to the end of the support arm by a bolt which has an extension allowed to pass through a slot in the fixed mounting bracket. An actuator rod extends from the servo actuator to a crank arm which turns a control shaft. A short linear thrust of the rod pivots the crank arm through about 90 for full-on control with the rod contracted into the servo actuator, and full-off control when the rod is extended from the actuator. A spring moves the servo actuator and actuator rod toward the control crank arm once the actuator rod is fully extended in the full-off position. This assures the turning of the control shaft to a full-off position. A stop bolt and slot are provided to limit pivot motion. Once fully extended, the spring pivots the motion.
    Keywords: MECHANICAL ENGINEERING
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  • 30
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    Fracture analysis of HPOTP bearing balls (1981)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: The fracture analysis conducted on four HPOTP (High Pressure Oxygen Turbopump) bearing balls from the SSME (Space Shuttle Main Engine) is described. Nondestructive evaluation, optical microscopy, and transmission microscopy techniques were used in the analysis. The cracks are initiated at or close to the ball surface under conditions of high cyclic stresses and high coefficient of friction. The cracks lead to spalls and subsequent crack propagation occurs by fatigue mode under concentrated loading of cyclic nature.
    Keywords: MECHANICAL ENGINEERING
    Type: NASA-TM-82428
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  • 31
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    Surface films and metallurgy related to lubrication and wear (1981)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: The nature of the tribological surface is identified and characterized with respect to adhesion, friction, wear, and lubricating properties. Surface analysis is used to identify the role of environmental constituents on tribological behavior. The effect of solid to solid interactions for metals in contact with metals, ceramics, semiconductors, carbons, and polymers is discussed. The data presented indicate that the tribological surface is markedly different than an ideal solid surface. The environment is shown to affect strongly the behavior of two solids in contact. Results also show that small amounts of alloying elements in base metals can alter markedly adhesion, friction, and wear by segregating to the solid surface.
    Keywords: MECHANICAL ENGINEERING
    Type: NASA-TM-82645 , E-900
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  • 32
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    Abradable dual-density ceramic turbine seal system (1981)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: A plasma sprayed dual density ceramic abradable seal system for direct application to the HPT seal shroud of small gas turbine engines. The system concept is based on the thermal barrier coating and depends upon an additional layer of modified density ceramic material adjacent to the gas flow path to provide the desired abradability. This is achieved by codeposition of inert fillers with yttria stabilized zirconia (YSZ) to interrupt the continuity of the zirconia struture. The investigation of a variety of candidate fillers, with hardness values as low as 2 on Moh's scale, led to the conclusion that solid filler materials in combination with a YSZ matrix, regardless of their hardness values, have a propensity for compacting rather than shearing as originally expected. The observed compaction is accompanied by high energy dissipation in the rub interaction, usually resulting in the adhesive transfer of blade material to the stationary seal member. Two YSZ based coating systems which incorported hollow alumino silicate spheres as density reducing agents were surveyed over the entire range of compositions from 100 percent filler to 100 percent YSZ. Abradability and erosion characteristics were determined, hardness and permeability characterized, and engine experience acquired with several system configurations.
    Keywords: MECHANICAL ENGINEERING
    Type: NASA-CR-165309 , EDR-10600
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  • 33
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    Large platform assembler non-structural system requirements (1981)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: The impact on the design and operation of an automated structure assembler of requiring the assembler to also install the platform electrical and/or fluid utility circuits was examined. Possible utility requirements were defined and examined in conjunction with the automated assembler. Preliminary concepts are presented which permit the electrical and fluid circuits to be installed with the structural elements.
    Keywords: MECHANICAL ENGINEERING
    Type: NASA-CR-165743 , LMSC-D760269
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  • 34
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    Tire/wheel concept (1981)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: A tire and wheel assembly is disclosed in which a low profile pneumatic tire (having sidewalls which deflect inwardly under load) and a wheel (having a rim featuring a narrow central channel and extended rim flanges) form the combination. The extended rim flanges support the tire sidewalls under static and dynamic loading conditions to produce a combination particularly suited to aircraft applications.
    Keywords: MECHANICAL ENGINEERING
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  • 35
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    Self-stabilizing radial face seal (1981)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: A self-stabilizing radial face seal comprises an axial member and a primary seal ring juxtapositioned to a seal seat. At least one primary seal ring and seal seat unit is affixed to the axial member so as to rotate with it. The primary seal ring has a front face which opposes a face of the seal seat. The seal has both high-pressure and low-pressure regions of fluid, and seal seat is provided with a porous ring-like circumferential structure in the face of the seal seat opposite the front face of the primary seal ring.
    Keywords: MECHANICAL ENGINEERING
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  • 36
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    An Experimental Evaluation of Oil Pumping Rings (1981)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: The design and construction of a reciprocating test vehicle to be used in evaluating hydrodynamic oil pumping rings are discussed. In addition, experimental test data are presented for three pumping ring designs that were constructed from Tin-Based Babbitt (SAE 11), Bearing Bronze (SAE 660), and Mechanical Carbon Graphite (Union Carbide Grade CNF-J). Data of pumped flow rate versus delivered pressure, as well as friction loss, are reported for the following conditions: frequencies of 10, 35 and 45 Hz; strokes of 25.4 mm (1.00 in.), 38.1 mm (1.50 in.) and 50.8 mm (2.00 in.) oil inlet temperature of 49 degrees (120 degrees); and pumping ring close-in pressures of 10.3 MPa (1500 lb/square inch. A 20W40 automotive oil was used for all tests. The maximum delivered pressure was 11 MPa (1600 lb/square inch. An analysis of hydrodynamic oil pumping rings was performed and the results of the analysis were compared to measured test data.
    Keywords: MECHANICAL ENGINEERING
    Type: NASA-CR-165271 , DOE/NASA/0119-81/1 , MTI-81TR3
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  • 37
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    An evaluation of grease type ball bearing lubricants operating in various environments (1981)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Because many future spacecraft or space stations will require mechanisms to operate for long periods of time in environments which are adverse to most bearing lubricants, a series of tests is continuing to evaluate 38 grease type lubricants in R-4 size bearings in five different environments for a 1 year period. Four repetitions of each test are made to provide statistical samples. These tests were used to select four lubricants for 5 year tests in selected environments with five repetitions of each test for statistical samples. At the present time, 100 test sets are completed and 22 test sets are underway. Three 5 year tests were started in (1) continuous operation and (2) start-stop operation, with both in vacuum at ambient temperatures, and (3) continuous operation at 93.3 C. In the 1 year tests the best results to date in all environments were obtained with a high viscosity index perfluoroalkylpolyether (PFPE) grease.
    Keywords: MECHANICAL ENGINEERING
    Type: NASA-TM-82391 , SR-5
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  • 38
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    Roller skewing measurements in cylindrical roller bearings (1981)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Measurements of roller skewing in a 118 mm bore roller bearing operating at shaft speeds to 12,000 rpm are reported. High speed motion pictures of a modified roller were taken through a derotation prism to record skewing as the roller moved through loaded and unloaded regions of the bearing. Subsequent frame by frame measurement of the photographic film provided information on roller skewing. Radial and tangential skew amplitudes of 0.4 to 0.5 degrees were observed with 0.5 degree misalignment.
    Keywords: MECHANICAL ENGINEERING
    Type: NASA-CR-3381
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  • 39
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    Transient dynamic analysis of high-speed lightly loaded cylindrical roller bearings. 1: Analysis (1981)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: The governing differential equations of motion for a high speed cylindrical roller bearing are developed under the assumptions that the bearing is isothermal and that the roller tilt and skew are very small. Two sets of differential equations are presented: the first which deals with planar motion of the roller bearing system; and the second which includes the effect of roller skewing. The equations as presented are in a format for programming on a digital computer.
    Keywords: MECHANICAL ENGINEERING
    Type: NASA-CR-3334
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  • 40
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    Precision heat forming of tetrafluoroethylene tubing (1981)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: An invention that provides a method of altering the size of tetrafluoroethylene tubing which is only available in limited combination of wall thicknesses and diameter are discussed. The method includes the steps of sliding the tetrafluoroethylene tubing onto an aluminum mandrel and clamping the ends of the tubing to the mandrel by means of clamps. The tetrafluorethylene tubing and mandrel are then placed in a supporting coil which with the mandrel and tetrafluorethylene tubing are then positioned in a insulated steel pipe which is normally covered with a fiber glass insulator to smooth out temperature distribution therein. The entire structure is then placed in an event which heats the tetrafluorethylene tubing which is then shrunk by the heat to the outer dimension of the aluminum mandrel. After cooling the aluminum mandrel is removed from the newly sized tetrafluorethylene tubing by a conventional chemical milling process.
    Keywords: MECHANICAL ENGINEERING
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  • 41
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    Suspension system for a wheel rolling on a flat track (1981)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: An improved suspension system for an uncrowned wheel rolling on a flat track is presented. It is characterized by a wheel frame assembly including a wheel frame and at least one uncrowned wheel connected in supporting relation with the frame. It is adapted to be seated in rolling engagement with a flat track, a load supporting bed, and a plurality of flexural struts interconnecting the bed in supported relation with the frame. Each of said struts is disposed in a plane passing through the center of the uncrowned wheel surface along a line substantially bisecting the line of contact established between the wheel surface and the flat surface of the truck and characterized by a modulus of elasticity sufficient for maintaining the axis of rotation for the wheel in substantial parallelism with the line of contact established between the surfaces of the wheel and track.
    Keywords: MECHANICAL ENGINEERING
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  • 42
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    Conventional engine technology. Volume 1: Status of OTTO cycle engine technology (1981)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Federally-mandated emissions standards have led to major changes in automotive technology during the last decade. Efforts to satisfy the new standards were directed more toward the use of add-on devices, such as catalytic converters, turbochargers, and improved fuel metering, than toward complete engine redesign. The resulting changes are described and the improvement brought about by them in fuel economy and emissions levels are fully documented. Four specific categories of gasoline-powered internal combustion engines are covered, including subsystem and total engine development. Also included are the results of fuel economy and exhaust emissions tests performed on representative vehicles from each category.
    Keywords: MECHANICAL ENGINEERING
    Type: NASA-CR-168643 , JPL-PUB-81-65-VOL-1 , DOE/CS-50194/1
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  • 43
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    Composite seal for turbomachinery (1981)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: A gas path seal suitable for use with a turbine engine or compressor is provided. A shroud wearable or abradable by the abrasion of the rotor blades of the turbine or compressor shrouds the rotor blades. A compliant backing surrounds the shroud. The backing is a yieldingly deformable porous material covered with a thin ductile layer. A mounting fixture surrounds the backing.
    Keywords: MECHANICAL ENGINEERING
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  • 44
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    Study of methods for applying and enhancing transfer film coatings of polytetrafluoroethylene (PTEE) to Space Shuttle Main Engine (SSME) High Pressure Oxygen Turbo Pump (HPOTP) bearings (1981)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Machines were constructed and evaluated for burnishing polytetrafluoroethylene on balls for use in the high pressure oxygen turbopump (HPOTP). The most positive performance was obtained with single-ball burnishing, but one technique for burnishing three balls simultaneously holds promise. Evaluations of the coatings in a HPOTP bearing of earlier design (employed smaller diameter balls) showed very little life enhancement before high torque and ball and race wear initiated. Other coating techniques, such as molybdenum disulfide combined with PTFE transfer films, hold promise for providing the more durable quantities of solid lubricant needed for the bearings.
    Keywords: MECHANICAL ENGINEERING
    Type: NASA-CR-161916
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  • 45
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    Scriber for silicon wafers (1981)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: A device for dividing silicon wafers into rectangular chips is characterized by a base including a horizontally oriented bed with a planar support surface, a vacuum chuck adapted to capture a silicon wafer seated on the support for translation in mutually perpendicular directions. A stylus support mounted on the bed includes a shaft disposed above and extended across the bed and a truck mounted on the shaft and supported thereby for linear translation along a path extended across the bed a vertically oriented scribe has a diamond tip supported by the truck also adapted as to engage a silicon wafer captured by the chuck and positioned beneath it in order to form score lines in the surface of the wafer as linear translation is imparted to the truck. A chuck positioning means is mounted on the base and is connected to the chuck for positioning the chuck relative to the stylus.
    Keywords: MECHANICAL ENGINEERING
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  • 46
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    Preliminary study of temperature measurement techniques for Stirling engine reciprocating seals (1981)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Methods of determining the contact surface temperature in reciprocating seals are investigated. Direct infrared measurement of surface temperatures of a rod exiting a loaded cap seal or simulated seal are compared with surface thermocouple measurements. Significant cooling of the surface requires several milliseconds so that exit temperatures may be considered representative of internal contact temperatures.
    Keywords: MECHANICAL ENGINEERING
    Type: NASA-CR-165479 , DOE/NASA/0227-1 , MTI82-TR-4
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  • 47
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    Surface geometry of circular cut spiral bevel gears (1981)
    In:  Other Sources
    Details
    Publication Date: 2019-07-27
    Description: An analysis of the surface geometry of spiral bevel gears formed by a circular cutter is presented. The emphasis is upon determining the tooth surface principal radii of curvature of crown (flat) gears. Specific results are presented for involute, straight, and hyperbolic cutter profiles. It is shown that the geometry of circular cut spiral bevel gears is somewhat simpler than a theoretical logarithmic spiral bevel gear.
    Keywords: MECHANICAL ENGINEERING
    Type: ASME PAPER 81-DET-114 , American Society of Mechanical Engineers, Design Engineering Technical Conference; Sept. 20-23, 1981; Hartford, CT
    Format: text
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  • 48
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    Optimal tooth numbers for compact standard spur gear sets (1981)
    In:  Other Sources
    Details
    Publication Date: 2019-07-27
    Description: The design of a standard gear mesh is treated with the objective of minimizing the gear size for a given ratio, pinion torque, and allowable tooth strength. Scoring, pitting fatigue, bending fatigue, and the kinematic limits of contact ratio and interference are considered. A design space is defined in terms of the number of teeth on the pinion and the diametral pitch. This space is then combined with the objective function of minimum center distance to obtain an optimal design region. This region defines the number of pinion teeth for the most compact design. The number is a function of the gear ratio only. A design example illustrating this procedure is also given.
    Keywords: MECHANICAL ENGINEERING
    Type: ASME PAPER 81-DET-115 , American Society of Mechanical Engineers, Design Engineering Technical Conference; Sept. 20-23, 1981; Hartford, CT
    Format: text
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  • 49
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    Head for high speed spinner having a vacuum chuck (1981)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: The head for a high-speed spinner is characterized by a substantially cylindrical body adapted to be mounted at the distal end of a vertically oriented drive shaft. A vacuum chuck with an upwardly facing chamber is circumscribed by an annular surface for receiving in supported relation a silicon chip. An ordered array of low-pressure cavities is defined about the periphery of the body and connected in communication with the chamber via radially extended bores in order to translate low pressures to the chamber as the head is angularly displaced. A pressure differential is thereby established across the chip for securing it to the head.
    Keywords: MECHANICAL ENGINEERING
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  • 50
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    Mechanical design handbook for elastomers (1981)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: A comprehensive guide for the design of elastomer dampers for application in rotating machinery is presented. Theoretical discussions, a step by step procedure for the design of elastomer dampers, and detailed examples of actual elastomer damper applications are included. Dynamic and general physical properties of elastomers are discussed along with measurement techniques.
    Keywords: MECHANICAL ENGINEERING
    Type: NASA-CR-3423 , MTI-81TR5
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  • 51
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    Circumferential shaft seal (1981)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: A circumferential shaft seal comprising two sealing rings held to a rotating shaft by means of a surrounding elastomeric band is disclosed. The rings are segmented and are of a rigid sealing material such as carbon or a polyimide and graphite fiber composite.
    Keywords: MECHANICAL ENGINEERING
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  • 52
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    Sandblasting nozzle (1981)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: A nozzle for use with abrasive and/or corrosive materials is formed of sintered ceramic compositions having high temperature oxidation resistance, high hardness and high abrasion and corrosion resistance. The ceramic may be a binary solid solution of a ceramic oxide and silicon nitride, and preferably a ternary solid solution of a ceramic oxide, silicon nitride and aluminum nitride. The ceramic oxide is selected from a group consisting of Al2O3, Y2O3 and Cr2O3, or mixtures of those compounds. Titanium carbide particles are dispersed in the ceramic mixture before sintering. The nozzles are encased for protection from external forces while in use by a metal or plastic casing.
    Keywords: MECHANICAL ENGINEERING
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  • 53
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    Hot gas engine with dual crankshafts (1981)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: A hot gas engine, such as a Stirling engine is described which comprises a displacer portion and an expander portion with a heat exchanger connected between them. The expander portion has a piston which is operatively connected to and rotates an expander crankshaft. In like manner, the displacer portion is provided with a piston which is also operatively connected to and rotates with a separate displacer crankshafts. The two crankshafts are synchronized with respect to each other preferably by means of an idler gear. Banks of displacer pistons can also be provided for operation on a common displacer crankshaft and banks of cooperating expander pistons also can be provided for operation on a common expander crankshaft.
    Keywords: MECHANICAL ENGINEERING
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  • 54
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    Multiple plate hydrostatic viscous damper (1981)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: A device for damping radial motion of a rotating shaft is described. The damper comprises a series of spaced plates extending in a radial direction. A hydraulic piston is utilized to place a load in these plates. Each annular plate is provided with a suitable hydrostatic bearing geometry on at least one of its faces. This structure provides a high degree of dampening in a rotor case system of turbomachinery in general. The damper is particularly useful in gas turbine engines.
    Keywords: MECHANICAL ENGINEERING
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  • 55
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    Latch mechanism for the space telescope (1981)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Latch mechanisms to secure, release, and relatch deployables on the Space Telescope are described. The latch mechanisms are mechanical pre-loading devices composed of a four-bar linkage driven by an electro-mechanical rotary actuator. The latch mechanism requirements, unique design features, analytical highlights, and the development testing are discussed.
    Keywords: MECHANICAL ENGINEERING
    Type: NASA. Marshall Space Flight Center The 15th Aerospace Mech. Symp.; p 331-339
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  • 56
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    Transfer film evaluation for shuttle engine turbopump bearing (1981)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: A series of low speed experiments to evaluate the possible occurrence of transfer film lubrication and the effectiveness of burnished films in the shuttle spacecraft main engine thrust bearings were conducted. No evidence of transfer film lubrication was evident, although this could have been the result of the (used) condition of the bearing. Burnished films of either Teflon or Rulon were found to greatly enhance the performance of the bearing. Crush load experiments indicated that the bearing ultimate load capability is on the order of 489,000 N (110,000 pounds). The effect of ball (as well as race) burnishing techniques on bearing performance, different types of burnished films, and transfer film formation are suggested for further study.
    Keywords: MECHANICAL ENGINEERING
    Type: NASA-CR-161672
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  • 57
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    Introduction to ball bearings (1981)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: The purpose of a ball bearing is to provide a relative positioning and rotational freedom while transmitting a load between two structures, usually a shaft and a housing. For high rotational speeds (e.g., in gyroscope ball bearings) the purpose can be expanded to include rotational freedom with practically no wear in the bearing. This condition can be achieved by separating the bearing parts with a coherent film of fluid known as an elastohydrodynamic film. This film can be maintained not only when the bearing carries the load on a shaft, but also when the bearing is preloaded to position the shaft to within micro- or nano-inch accuracy and stability. Background information on ball bearings is provided, different types of ball bearings and their geometry and kinematics are defined, bearing materials, manufacturing processes, and separators are discussed. It is assumed, for the purposes of analysis, that the bearing carries no load.
    Keywords: MECHANICAL ENGINEERING
    Type: NASA-TM-81690 , E-209
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  • 58
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    Small passenger car transmission test: Mercury Lynx ATX transmission (1981)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: The testing of a Mercury Lynx automatic transmission is reported. The transmission was tested in accordance with a passenger car automatic transmission test code (SAE J65lb) which required drive performance, coast performance, and no load test conditions. Under these conditions, the transmission attained maximum efficiencies in the mid-ninety percent range both for drive performance test and coast performance tests. The torque, speed, and efficiency curves are presented, which provide the complete performance characteristics for the Mercury Lynx automatic transmission.
    Keywords: MECHANICAL ENGINEERING
    Type: NASA-CR-165510 , DOE/NASA/0124-7 , NAS 1.26:165510 , ERC-TR-8191
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  • 59
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    Conventional engine technology. Volume 2: Status of diesel engine technology (1981)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: The engines of diesel cars marketed in the United States were examined. Prominent design features, performance characteristics, fuel economy and emissions data were compared. Specific problems, in particular those of NO and smoke emissions, the effects of increasing dieselization on diesel fuel price and availability, current R&D work and advanced diesel concepts are discussed. Diesel cars currently have a fuel economy advantage over gasoline engine powered cars. Diesel drawbacks (noise and odor) were reduced to a less objectionable level. An equivalent gasoline engine driveability was obtained with turbocharging. Diesel manufacturers see a growth in the diesel market for the next ten years. Uncertainties regarding future emission regulation may inhibit future diesel production investments. With spark ignition engine technology advancing in the direction of high compression ratios, the fuel economy advantages of the diesel car is expected to diminish. To return its fuel economy lead, the diesel's potential for future improvement must be used.
    Keywords: MECHANICAL ENGINEERING
    Type: NASA-CR-168644 , JPL-PUB-81-65-VOL-2 , DOE/CS-50194/1
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  • 60
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    Conventional engine technology. Volume 3: Comparisons and future potential (1981)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: The status of five conventional automobile engine technologies was assessed and the future potential for increasing fuel economy and reducing exhaust emission was discussed, using the 1980 EPA California emisions standards as a comparative basis. By 1986, the fuel economy of a uniform charge Otto engine with a three-way catalyst is expected to increase 10%, while vehicles with lean burn (fast burn) engines should show a 20% fuel economy increase. Although vehicles with stratified-charge engines and rotary engines are expected to improve, their fuel economy will remain inferior to the other engine types. When adequate NO emissions control methods are implemented to meet the EPA requirements, vehicles with prechamber diesel engines are expected to yield a fuel economy advantage of about 15%. While successful introduction of direct injection diesel engine technology will provide a fuel savings of 30 to 35%, the planned regulation of exhaust particulates could seriously hinder this technology, because it is expected that only the smallest diesel engine vehicles could meet the proposed particulate requirements.
    Keywords: MECHANICAL ENGINEERING
    Type: NASA-CR-168645 , JPL-PUB-81-VOL-3 , DOE/CS-50194/1
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  • 61
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    Moving body velocity arresting line (1981)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: The arresting of a moving body is improved through the use of steel cables that elongate to absorb the kinetic energy of the body. A sleeve surrounds the cables, protecting them from chafing and providing a failsafe energy absorbing system should the cables fail.
    Keywords: MECHANICAL ENGINEERING
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  • 62
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    Basic lubrication equations (1981)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Lubricants, usually Newtonian fluids, are assumed to experience laminar flow. The basic equations used to describe the flow are the Navier-Stokes equation of motion. The study of hydrodynamic lubrication is, from a mathematical standpoint, the application of a reduced form of these Navier-Stokes equations in association with the continuity equation. The Reynolds equation can also be derived from first principles, provided of course that the same basic assumptions are adopted in each case. Both methods are used in deriving the Reynolds equation, and the assumptions inherent in reducing the Navier-Stokes equations are specified. Because the Reynolds equation contains viscosity and density terms and these properties depend on temperature and pressure, it is often necessary to couple the Reynolds with energy equation. The lubricant properties and the energy equation are presented. Film thickness, a parameter of the Reynolds equation, is a function of the elastic behavior of the bearing surface. The governing elasticity equation is therefore presented.
    Keywords: MECHANICAL ENGINEERING
    Type: NASA-TM-81693 , E-209
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  • 63
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    Traction contact performance evaluation at high speeds (1981)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: The results of traction tests performed on two fluids are presented. These tests covered a pressure range of 1.0 to 2.5 GPa, an inlet temperature range of 30 'C to 70 'C, a speed range of 10 to 80 m/sec, aspect ratios of .5 to 5 and spin from 0 to 2.1 percent. The test results are presented in the form of two dimensionless parameters, the initial traction slope and the maximum traction peak. With the use of a suitable rheological fluid model the actual traction curves measured can now be reconstituted from the two fluid parameters. More importantly, the knowledge of these parameters together with the fluid rheological model, allow the prediction of traction under conditions of spin, slip and any combination thereof. Comparison between theoretically predicted traction under these conditions and those measured in actual traction tests shows that this method gives good results.
    Keywords: MECHANICAL ENGINEERING
    Type: NASA-CR-165226 , DOE/NASA/0035-1
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  • 64
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    Surface conforming thermal/pressure seal (1981)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: An assembly is disclosed for sealing a variable gap between the surface of element and a second element in movable relation to it. A seal housing is attached to the second element for movement therewith and has a sealing surface. At least one elongated seal member carried by the housing has first and second conjugate sealing surfaces. The first sealing surface is for rubbing and sealing engagement with the first element surface and the second sealing surface is for sliding and sealing engagement with the housing sealing surface. A biasing assembly may be carried by the housing for biasing the first and second conjugate sealing surfaces of the sealing member toward sealing engagement with the first element surface and housing sealing surface, respectively.
    Keywords: MECHANICAL ENGINEERING
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  • 65
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    Open ended tubing cutters (1981)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: A self clamping cutting tool which includes a handle attached to a C-shaped housing is described. Rotatably mounted within the housing is a C-shaped tool body carrying a set of clamping rolls, two support rolls, and an edged cutting roll (64). The support rolls are disposed to one side of the axis of a pipe and the cutting roll is disposed to the other side of a pipe axis so that these rolls contact a pipe at three circumferential points. Cutter advancing apparatus advance the cutting roll toward the support rollers. The support rolls and cutting roll are rotatable independently of the C-shaped housing. A one way ratchet mechanism disposed between the C-shaped housing and the C-shaped tool body permits operation by movement in one rotational direction about the pipe axis.
    Keywords: MECHANICAL ENGINEERING
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  • 66
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    Convergent-tapered annular seals - Analysis for rotordynamic coefficients (1981)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: A combined analytical-computational solution based on Hirs' lubrication equations (1970) is developed for tapered high-pressure annular seals typical of neck-ring and interstage seals employed in multistage centrifugal pumps. The results obtained coincide with earlier straight seal results at taper angles approaching zero and, under comparable assumptions, agree with Fleming's (1977) predictions for the direct stiffness coefficients. An optimal taper angle is shown to exist with respect to direct stiffness and the ratio of direct stiffness to leakage. Stiffness increases of about 85% are predicted.
    Keywords: MECHANICAL ENGINEERING
    Type: Fluid/structure interactions in turbomachinery; Nov 15, 1981 - Nov 20, 1981; Washington, DC
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  • 67
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    Rub energetics of compressor blade tip seals (1981)
    In:  Other Sources
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    Publication Date: 2019-07-13
    Description: The rub mechanics of aircraft gas turbine engine compressor abradable blade tip seals was studied at simulated engine conditions. In 12 statistically planned, instrumented rub tests using single titanium blades and fiber-metal rubstrips the rub velocity, incursion rate, incursion depth, blade thickness, and abradable strength were varied to determine the effects on rub energy, heat split between the blade, rubstrip surface and rub debris, and blade and seal wear. The rub energies were found to be most significantly affected by the incursion rate while rub velocity and blade thickness were of secondary importance. In five additional rub tests using single nickel alloy blades and multiple titanium alloy blades, rub energy and wear effects were found to be similar for titanium and nickel alloy blades while rub energies increased for multiple blades relative to single blade test results.
    Keywords: MECHANICAL ENGINEERING
    Type: In: Wear of materials 1981; Mar 30, 1981 - Apr 01, 1981; San Francisco, CA
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  • 68
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    Development of CdO-graphite-Ag coatings for gas bearings to 427 C (1981)
    In:  Other Sources
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    Publication Date: 2019-07-13
    Description: Graphite is one of the most commonly known lubricants. Its effectiveness in a range between room temperature (RT) and 540 C is reportedly improved by adding cadmium oxide. CdO-graphite powder in a gas carrier has been used in numerous applications that rely on dry lubrication. A coating of this composition was developed and successfully tested in foil air bearings for long periods up to a temperature of 427 C and at a normal contacting load (during starting and stopping) of 14 kPa based on bearing projected area. The addition of ultra-fine silver to the CdO-graphite has improved the coating endurance. At 427 C, the CdO-graphite-Ag coating performed better than CdO-graphite without silver, both for extended periods at 14 kPa loading and for limited periods at 35 kPa. At 288 C, the coating was tested for an extended period up to 28 kPa and has also successfully completed high-speed shock tests to an acceleration level of 100g.
    Keywords: MECHANICAL ENGINEERING
    Type: In: Wear of materials 1981; Mar 30, 1981 - Apr 01, 1981; San Francisco, CA
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  • 69
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    Effect of load, area of contact, and contact stress on the tribological properties of polyimide bonded graphite fluoride films (1981)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: A pin-on-disk type of friction and wear apparatus was used to study the effect of load, contact stress and rider area of contact on the friction and wear properties of polyimide-bonded graphite fluoride films. Different rider area contacts were obtained by initially generating flats (with areas of 0.0035, 0.0071, 0.0145, and 0.0240 cm) on 0.476-cm radius hemispherically-tipped riders. Different projected contact stresses were obtained by applying loads of 2.5-to 58.8-N to the flats. Two film wear mechanisms were observed. The first was found to be a linear function of contact stress and was independent of rider area of contact. The second was found to increase exponentially as the stress increased. The second also appeared to be a function of rider contact area. Wear equations for each mechanism were empirically derived from the experimental data. In general, friction coefficients increased with increasing rider contact area and with sliding duration. This was related to the build-up of thick rider transfer films.
    Keywords: MECHANICAL ENGINEERING
    Type: In: Wear of materials 1981; Mar 30, 1981 - Apr 01, 1981; San Francisco, CA
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  • 70
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    Effect of mechanical surface and heat treatments on erosion resistance (1981)
    In:  Other Sources
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    Publication Date: 2019-07-13
    Description: The effect of erosion by glass beads and crushed glass and by heat treatments on the erosional resistance of 6061 aluminum alloy and 1045 steel were studied. The aluminum alloy's erosion resistance was found to be insensitive to mechanical surface treatment applied before testing, and was determined to depend on the properties of the work-hardened surface layer; this was also demonstrated for aluminum alloy single crystals. The aluminum alloy heat treatments included annealing, solution, and precipitation. Solution was found to increase erosion resistance but precipitation had the opposite effect. Hardness showed no correlation with erosion resistance for either aluminum alloy steel. The steel tests showed that crushed glass provides an order of magnitude more erosion than glass beads.
    Keywords: MECHANICAL ENGINEERING
    Type: In: Wear of materials 1981; Mar 30, 1981 - Apr 01, 1981; San Francisco, CA
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  • 71
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    Anisotropic tribological properties of silicon carbide (1981)
    In:  Other Sources
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    Publication Date: 2019-07-13
    Description: The effects of crystallographic orientation on the tribological properties of single-crystal silicon carbide surfaces in contact with various solids are investigated for adhesive and abrasive wear processes. In the adhesive wear process, the adhesion and wear of silicon carbide is found to be markedly dependent on crystallographic orientation. The force resisting shearing fracture of the adhesive bonds at the interface is lower in preferred crystallographic direction of slip. In the abrasive wear process, the 1 0 -1 0 direction on the basal plane of silicon carbide exhibits the lowest coefficient of friction and the greatest resistance to abrasion.
    Keywords: MECHANICAL ENGINEERING
    Type: In: Wear of materials 1981; Mar 30, 1981 - Apr 01, 1981; San Francisco, CA
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  • 72
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    Helicopter vibration suppression using simple pendulum absorbers on the rotor blade (1981)
    In:  Other Sources
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    Publication Date: 2019-07-13
    Description: A design procedure is presented for the installation of simple pendulums on the blades of a helicopter rotor to suppress the root reactions. The procedure consists of a frequency response analysis for a hingeless rotor blade excited by a harmonic variation of spanwise airload distributions during forward flight, as well as a concentrated load at the tip. The structural modeling of the blade provides for elastic degrees of freedom in flap and lead-lag bending plus torsion. Simple flap and lead-lag pendulums are considered individually. Using a rational order scheme, the general nonlinear equations of motion are linearized. A quasi-steady aerodynamic representation is used in the formation of the airloads. The solution of the system equations derives from their representation as a transfer matrix. The results include the effect of pendulum tuning on the minimization of the hub reactions.
    Keywords: MECHANICAL ENGINEERING
    Type: National Specialists Meeting on Helicopter Vibration; Nov 02, 1981 - Nov 04, 1981; Hartford, CT
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  • 73
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    Sputtering and ion plating for aerospace applications (1981)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: Sputtering and ion plating technologies are reviewed in terms of their potential and present uses in the aerospace industry. Sputtering offers great universality and flexibility in depositing any material or in the synthesis of new ones. The sputter deposition process has two areas of interest: thin film and fabrication technology. Thin film sputtering technology is primarily used for aerospace mechanical components to reduce friction, wear, erosion, corrosion, high temperature oxidation, diffusion and fatigue, and also to sputter-construct temperature and strain sensors for aircraft engines. Sputter fabrication is used in intricate aircraft component manufacturing. Ion plating applications are discussed in terms of the high energy evaporant flux and the high throwing power. Excellent adherence and 3-dimensional coverage are the primary attributes of this technology.
    Keywords: MECHANICAL ENGINEERING
    Type: National Conference; Jun 28, 1981 - Jul 02, 1981; Boston, MA
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  • 74
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    Ion plating for the future (1981)
    In:  Other Sources
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    Publication Date: 2019-07-13
    Description: The ion plating techniques are classified relative to the instrumental set up, evaporation media and mode of transport. Distinction is drawn between the low vacuum (plasma) and high vacuum (ion beam) techniques. Ion plating technology is discussed at the fundamental and industrial level. At the fundamental level, the capabilities and limitations of the plasma (evaporant flux) and film characteristics are evaluated. On the industrial level, the performance and potential uses of ion plated films are discussed.
    Keywords: MECHANICAL ENGINEERING
    Type: Annual Technical Conference; May 12, 1981 - May 14, 1981; Dearborn, MI
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  • 75
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    Ion source design for industrial applications (1981)
    In:  Other Sources
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    Publication Date: 2019-07-13
    Description: The more frequently used design techniques for the components of broad-beam electron bombardment ion sources are discussed. The approach used emphasizes refractory metal cathodes and permanent-magnet multipole discharge chambers. Design procedures and sample calculations are given for the discharge chamber, ion optics, the cathodes, and the magnetic circuit. Hardware designs are included for the isolator, cathode supports, anode supports, pole-piece assembly, and ion-optics supports. A comparison is made between two-grid and three-grid optics. The designs presented are representative of current technology and are adaptable to a wide range of configurations.
    Keywords: MECHANICAL ENGINEERING
    Type: AIAA PAPER 81-0668 , International Electric Propulsion Conference; Apr 21, 1981 - Apr 23, 1981; Las Vegas, NV; US
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  • 76
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    Surface geometry of circular cut spiral bevel gears (1981)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: The tooth surface principal radii of curvature of crown (flat) gears were determined. Specific results are presented for involute, straight, and hyperbolic cutter profiles. It is shown that the geometry of circular cut spiral bevel gears is somewhat simpler than a theoretical logarithmic spiral bevel gear.
    Keywords: MECHANICAL ENGINEERING
    Type: NASA-TM-82622 , E-873 , AVRADCOM-TR-81-C-13 , The Design Eng. Tech. Conf.; Sep 20, 1981 - Sep 23, 1981; Hartford, CT; United States
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  • 77
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    Sputtering and ion plating for aerospace applications (1981)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Sputtering and ion plating technologies are reviewed in terms of their potential and present uses in the aerospace industry. Sputtering offers great universality and flexibility in depositing any material or in the synthesis of new ones. The sputter deposition process has two areas of interest: thin film and fabrication technology. Thin film sputtering technology is primarily used for aerospace mechanical components to reduce friction, wear, erosion, corrosion, high temperature oxidation, diffusion and fatigue, and also to sputter-construct temperature and strain sensors for aircraft engines. Sputter fabrication is used in intricate aircraft component manufacturing. Ion plating applications are discussed in terms of the high energy evaporant flux and the high throwing power. Excellent adherence and 3 dimensional coverage are the primary attributes of this technology.
    Keywords: MECHANICAL ENGINEERING
    Type: NASA-TM-81726 , E-778 , Natl. Conf. of the Am. Electroplaters Soc.,; Jun 28, 1981 - Jul 02, 1981; Boston, MA; United States
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  • 78
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    Advanced Gas Turbine (AGT) powertrain system development for automotive applications (1981)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Preliminary layouts were made for the exhaust system, air induction system, and battery installation. Points of interference were identified and resolved by altering either the vehicle or engine designs. An engine general arrangement evolved to meet the vehicle engine compartment constraints while minimizing the duct pressure losses and the heat rejection. A power transfer system (between gasifier and power turbines) was developed to maintain nearly constant temperatures throughout the entire range of engine operation. An advanced four speed automatic transmission was selected to be used with the engine. Performance calculations show improvements in component efficiencies and an increase in fuel economy. A single stage centrifugal compressor design was completed and released for procurement. Gasifier turbine, power turbine, combustor, generator, secondary systems, materials, controls, and transmission development are reported.
    Keywords: MECHANICAL ENGINEERING
    Type: NASA-CR-165178 , DOE/NASA/0168-80/1 , NAS 1.26:165178 , DDA-EDR-10327 , SAR-1
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  • 79
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    Advanced superposition methods for high speed turbopump vibration analysis (1981)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: The small, high pressure Mark 48 liquid hydrogen turbopump was analyzed and dynamically tested to determine the cause of high speed vibration at an operating speed of 92,400 rpm. This approaches the design point operating speed of 95,000 rpm. The initial dynamic analysis in the design stage and subsequent further analysis of the rotor only dynamics failed to predict the vibration characteristics found during testing. An advanced procedure for dynamics analysis was used in this investigation. The procedure involves developing accurate dynamic models of the rotor assembly and casing assembly by finite element analysis. The dynamically instrumented assemblies are independently rap tested to verify the analytical models. The verified models are then combined by modal superposition techniques to develop a completed turbopump model where dynamic characteristics are determined. The results of the dynamic testing and analysis obtained are presented and methods of moving the high speed vibration characteristics to speeds above the operating range are recommended. Recommendations for use of these advanced dynamic analysis procedures during initial design phases are given.
    Keywords: MECHANICAL ENGINEERING
    Type: NASA-CR-165379 , RI/RD81-149
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  • 80
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    Rehabilitation of 64-meter-antenna radial bearing (1981)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: The performances of the radial bearings on three 64-meter antennas are presented. Explanations for the distortion of the bearing at DSS 14 are made and the repairs are described. Recommendations for future tests and action are given.
    Keywords: MECHANICAL ENGINEERING
    Type: The Telecommun. and Data Acquisition Rept.; p 151-161
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  • 81
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    Magnetohydrodynamics (MHD) Engineering Test Facility (ETF) 200 MWe power plant. Design Requirements Document (DRD) (1981)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: A description and the design requirements for the 200 MWe (nominal) net output MHD Engineering Test Facility (ETF) Conceptual Design, are presented. Performance requirements for the plant are identified and process conditions are indicated at interface stations between the major systems comprising the plant. Also included are the description, functions, interfaces and requirements for each of these major systems. The lastest information (1980-1981) from the MHD technology program are integrated with elements of a conventional steam electric power generating plant.
    Keywords: MECHANICAL ENGINEERING
    Type: NASA-TM-82705 , DOE/NASA/10769-20-REV-3
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  • 82
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    Ionospheric propagation correction modeling for satellite altimeters (1981)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: The theoretical basis and avaliable accuracy verifications were reviewed and compared for ionospheric correction procedures based on a global ionsopheric model driven by solar flux, and a technique in which measured electron content (using Faraday rotation measurements) for one path is mapped into corrections for a hemisphere. For these two techniques, RMS errors for correcting satellite altimeters data (at 14 GHz) are estimated to be 12 cm and 3 cm, respectively. On the basis of global accuracy and reliability after implementation, the solar flux model is recommended.
    Keywords: MECHANICAL ENGINEERING
    Type: NASA-CR-156881
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  • 83
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    Modified face seal for positive film stiffness (1981)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: The film stiffness of a face seal is improved without increasing the sealing and dam area by using an apparatus which includes a primary seal ring in the form of a nose piece. A spring forces a sealing surface on the seal ring into sealing contact with a seat to form a face seal. A circumferential clearance seal is formed in series with this face seal by a lip on the piece. The width of the surface of the lip is substantially the same as the width of the sealing surface on the face seal and the clearance between the surface on the lip and the shaft is substantially the same as the spacing between the face sealing surfaces on the face seal when the shaft is rotating. The circumferential clearance seal restricts the flow of fluid from a main cavity to an intermediate cavity with a resulting pressure drop. The hydrostatic opening face is strongly dependent on the face seal clearance, and the desired axial stiffness is achieved.
    Keywords: MECHANICAL ENGINEERING
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  • 84
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    Liquid immersion apparatus for minute articles (1981)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Apparatus is disclosed for immersing minute integrated circuit chips in an etching solution in manufacturing integrated circuits during research and development. The apparatus includes a holder, having a handle and basket support for carrying a removable unitary basket and lid structure where fluid flow-through passages are formed, and wherein graduated openings in the handle provide for adjustably supporting the basket in a breaker at a desired level.
    Keywords: MECHANICAL ENGINEERING
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  • 85
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    AGT-102 automotive gas turbine (1981)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Development of a gas turbine powertrain with a 30% fuel economy improvement over a comparable S1 reciprocating engine, operation within 0.41 HC, 3.4 CO, and 0.40 NOx grams per mile emissions levels, and ability to use a variety of alternate fuels is summarized. The powertrain concept consists of a single-shaft engine with a ceramic inner shell for containment of hot gasses and support of twin regenerators. It uses a fixed-geometry, lean, premixed, prevaporized combustor, and a ceramic radial turbine rotor supported by an air-lubricated journal bearing. The engine is coupled to the vehicle through a widerange continuously variable transmission, which utilizes gearing and a variable-ratio metal compression belt. A response assist flywheel is used to achieve acceptable levels of engine response. The package offers a 100 lb weight advantage in a Chrysler K Car front-wheel-drive installation. Initial layout studies, preliminary transient thermal analysis, ceramic inner housing structural analysis, and detailed performance analysis were carried out for the basic engine.
    Keywords: MECHANICAL ENGINEERING
    Type: NASA-CR-165353 , DOE/NASA/2749-81/1
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  • 86
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    Low-thrust chemical propulsion system pump technology (1981)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Candidate pump and driver systems for low thrust cargo orbit transfer vehicle engines which deliver large space structures to geosynchronous equatorial orbit and beyond are evaluated. The pumps operate to 68 atmospheres (1000 psi) discharge pressure and flowrates suited to cryogenic engines using either LOX/methane or LOX/hydrogen propellants in thrust ranges from 445 to 8900 N (100 to 2000 lb F). Analysis of the various pumps and drivers indicate that the low specific speed requirement will make high fluid efficiencies difficult to achieve. As such, multiple stages are required. In addition, all pumps require inducer stages. The most attractive main pumps are the multistage centrifugal pumps.
    Keywords: MECHANICAL ENGINEERING
    Type: NASA-CR-165219
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  • 87
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    Liquid oxygen turbopump technology (1981)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: A small, high-pressure, LOX turbopump was designed, fabricated and tested. The pump is a single-stage centrifugal type with power to the pump supplied by a single-stage partial-admission axial-impulse turbine. Design conditions included an operating speed of 7330 rad/s (70,000 rpm), pump discharge pressure of 2977 N/sqcm (4318 psia), and a pump flowrate of 16.4 Kg/s (36.21 lb/s). The turbopump contains a self-compensating axial thrust balance piston to eliminate axial thrust loads on the bearings during steady-state operation. Testing of the turbopump was achieved usng a gaseous hydrogen high-pressure flow to drive the turbine, which generally is propelled by LOX/LH2 combustion products, at 1041K (1874 R) inlet temperature and at a design pressure ratio of 1.424. Test data obtained with the turbopump are presented which include head-flow-efficiency performance, suction performance, balance piston performance and LOX seal performance. Mechanical performance of the turbopump is also discussed.
    Keywords: MECHANICAL ENGINEERING
    Type: NASA-CR-165487 , RI/RD81-199
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  • 88
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    Modular antenna design study (1981)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: The mechanical design of a modular antenna concept was developed sufficiently to allow manufacture of a working demonstration model of a module, to predict mass properties, and to make performance estimates for antenna reflectors composed of these modules. The primary features of this concept are: (1) each module is an autonomous structural element which can be attached to adjacent modules through a three point connection; (2) the upper surface is a folding hexagonal truss plate mechanism which serves as the supporting structure for a reflective surface; and (3) the entire truss and surface can be folded into a cylindrical envelope in which all truss elements are essentially parallel. The kinematic studies and engineering demonstration model fully verified the deployment kinematics, stowing philosophy, and deployment sequencing for large antenna modules. It was established that such modules can be stowed in packages as small as 25 cm in diameter, using 1.27 cm diameter structural tubes. The development activity indicates that this deployable modular approach towards building large structures in space will support erection of 450 m apertures for operation up to 3 GHz with a single space shuttle flight.
    Keywords: MECHANICAL ENGINEERING
    Type: NASA-CR-3316 , LMSC-D714622
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    Analysis of the market for a new frozen coal release device (1981)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Conditions that contribute to coal freezing and the costs of frozen coal handling are discussed. The various methods currently used to handle frozen coal are examined and assessed relative to costs, effectiveness, and advantages and disadvantages. A NASA designed gas detonation lance for breaking the ice bonds between frozen coal nuggets is described and illustrated. Market demand for the controlled gas detonation lance is estimated to be at least 10 units.
    Keywords: MECHANICAL ENGINEERING
    Type: NASA-CR-170101 , NAS 1.26:170101
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    Magnetohydrodynamics (MHD) Engineering Test Facility (ETF) 200 MWe power plant. Conceptual Design Engineering Report (CDER) supplement. Magnet system special investigations (1981)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: The results of magnet system special investigations listed below are summarized: 4 Tesla Magnet Alternate Design Study; 6 Tesla Magnet Manufacturability Study. The conceptual design for a 4 Tesla superconducting magnet system for use with an alternate (supersonic) ETF power train is described, and estimated schedule and cost are identified. The magnet design is scaled from the ETF 6 T Tesla design. Results of a manufacturability study and a revised schedule and cost estimate for the ETF 6 T magnet are reported. Both investigations are extensions of the conceptual design of a 6 T magnet system performed earlier as a part of the overall MED-ETF conceptual design described in Conceptual Design Engineering Report (CDER) Vol. V, System Design Description (SDD) 503 dated September, 1981, DOE/NASA/0224-1; NASA CR-165/52.
    Keywords: MECHANICAL ENGINEERING
    Type: NASA-CR-165509 , DOE/NASA/0100-1 , NAS 1.26:165509 , NAS-E-1
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    Fully plasma-sprayed compliant backed ceramic turbine seal (1981)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: A seal with a high temperature abradable lining material which encircles the tips of turbine blades in turbomachinery was designed. The seal is directed to maintaining the minimum operating clearances between the blade tips and the lining of a high pressure turbine. A low temperature easily decomposable material in powder form is blended with a high temperature oxidation resistant metal powder. The two materials are simultaneously deposited on a substrate formed by the turbine casing. Alternately, the polymer powder may be added to the metal powder during plasma spraying. A ceramic layer is then deposited directly onto the metal-polymer composite. The polymer additive mixed with the metal is then completely volatilized to provide a porous layer between the ceramic layer and the substrate. Thermal stresses are reduced by the porous structure which gives a cushion effect. No brazing is required by using only plasma spraying for depositing both the powders of the metal and polymer material as well as the ceramic powder.
    Keywords: MECHANICAL ENGINEERING
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  • 92
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    Observation of pressure variation in the cavitation region of submerged journal bearings (1981)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: Visual observations and pressure measurements in the cavitation zone of a submerged journal bearing are described. Tests are run at speeds of 1840 and 3000 rpm, and at each speed, four different levels of the ambient supply pressure are applied, ranging from 13.6 KPa to 54.4 KPa. A strong reverse flow is detected inside the cavitation area adjacent to its downstream end, and significant pressure variations on the order of 50 KPa are found inside the cavitation region at the downstream portion of its circumferential extent. Results indicate that the assumption of a constant cavitation pressure is incorrect in the case of enclosed cavitations, and it is postulated that oil which is saturated with air under atmospheric pressure becomes oversaturated in the subcavity pressure loop.
    Keywords: MECHANICAL ENGINEERING
    Type: ASME PAPER 81-LUB-11 , Joint Lubrication Conference; Oct 05, 1981 - Oct 07, 1981; New Orleans, LA
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  • 93
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    Regimes of traction in concentrated contact lubrication (1981)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: Experimental evidence is presented for the existence of three regimes of traction in concentrated contacts. Data are obtained in a rolling contact simulator by varying the lubricant, temperature, rolling speed, load and surface roughness at a fixed slide-to-roll ratio. At lower thicknesses the mixed regime is encountered, and traction is increased due to asperity interaction, while at higher film thicknesses, the lubricant pressure is distributed over a greater area than the Hertzian region, resulting in a lower average pressure and reduced traction.
    Keywords: MECHANICAL ENGINEERING
    Type: ASME PAPER 81-LUB-16 , Joint Lubrication Conference; Oct 05, 1981 - Oct 07, 1981; New Orleans, LA
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    Stress concentration in the vicinity of a hole defect under conditions of Hertzian contact (1981)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: Two-dimensional photoelastic stress analyses were conducted for epoxy resin models containing a hole defect under the conditions of Hertzian contact. Stress concentrations around the defect were determined as a function of several parameters. These were hole diameter, its vertical distance from the contact surface, and the horizontal distance from the Hertzian contact area. Also determined was the effect of tangential traction (generated by a friction coefficient of 0.1) on the stress concentration. Sharp stress concentrations occur in the vicinity of both the left and the right side of the hole. The stress concentration becomes more distinct the larger the hole diameter and the smaller the distance between the hole and the contact surface. The stress concentration is greatest when the disk imposing a normal load is located at the contact surface directly over the hole. The magnitude and the location of stress concentration varies with the distance between the Hertzian contact area and the hole. Taking into account the stress amplitude, the area which can be involved in a process of rolling contact fatigue seems to be confined to a shallow region at both sides of the hole. The effect of tangential traction is comparatively small on the stress concentration around the hole.
    Keywords: MECHANICAL ENGINEERING
    Type: ASLE PREPRINT 81-LC-6B-2 , Lubrication Conference; Oct 05, 1981 - Oct 07, 1981; New Orleans, LA
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  • 95
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    The AGT101 technology - An automotive alternative (1981)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: The Advanced Gas Turbine Powertrain System Development Project is oriented at providing the United States automotive industry the technology base necessary to produce gas turbine powertrains for automotive applications that will have: (1) reduced fuel consumption, (2) the ability to use a variety of fuels, (3) low emissions, and (4) competitive cost/performance. The AGT101 powertrain being developed consists of a regenerated single-shaft gas turbine engine flat rated at 74.6 kW (100 hp) coupled to a split-differential gearbox and a Ford automatic overdrive production transmission. Performance predictions for the AGT101 powertrain represent a 59-percent improvement in mileage estimates over a 1985 conventionally-powered automobile for the combined federal driving cycle.
    Keywords: MECHANICAL ENGINEERING
    Type: In: Intersociety Energy Conversion Engineering Conference; Aug 09, 1981 - Aug 14, 1981; Atlanta, GA
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  • 96
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    Effects of artificially produced defects on film thickness distribution in sliding EHD point contacts (1981)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: The effects of artificially produced dents and grooves on the elastohydrodynamic (EHD) film thickness profile in a sliding point contact were investigated by means of optical interferometry. The defects, formed on the surface of a highly polished ball, were held stationary at various locations within and in the vicinity of the contact region while the disk was rotating. It is shown that the defects, having a geometry similar to what can be expected in practice, can dramatically change the film thickness which exists when no defects are present in or near the contact. This change in film thickness is mainly a function of the position of the defects in the inlet region, the geometry of the defects, the orientation of the defects in the case of grooves, and the depth of the defect relative to the central film thickness.
    Keywords: MECHANICAL ENGINEERING
    Type: NASA-TM-82732 , E-1042 , Joint Lubrication Conf.; Oct 05, 1981 - Oct 07, 1981; New Orleans, LA; United States
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  • 97
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    Application of surface analysis to solve problems of wear (1981)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Results are presented for the use of surface analytical tools including field ion microscopy, Auger emission spectroscopy analysis (AES), cylindrical mirror Auger analysis and X-ray photoelectron spectroscopy (XPS). Data from the field ion microscope reveal adhesive transfer (wear) at the atomic level with the formation of surface compounds not found in the bulk, and AES reveals that this transfer will occur even in the presence of surface oxides. Both AES and XPS reveal that in abrasive wear with silicon carbide and diamond contacting the transition metals, the surface and the abrasive undergo a chemical or structural change which effects wear. With silicon carbide, silicon volatilizes leaving behind a pseudo-graphitic surface and the surface of diamond is observed to graphitize.
    Keywords: MECHANICAL ENGINEERING
    Type: NASA-TM-82753 , E-1069 , Ideele Traeger der SURTEC Berlin ''81; Jun 29, 1981 - Jul 03, 1981; Berlin; Germany
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  • 98
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    JT8D high pressure compressor performance improvement (1981)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: An improved performance high pressure compressor with potential application to all models of the JT8D engine was designed. The concept consisted of a trenched abradable rubstrip which mates with the blade tips for each of the even rotor stages. This feature allows tip clearances to be set so blade tips run at or near the optimum radius relative to the flowpath wall, without the danger of damaging the blades during transients and maneuvers. The improved compressor demonstrated thrust specific fuel consumption and exhaust gas temperature improvements of 1.0 percent and at least 10 C over the takeoff and climb power range at sea level static conditions, compared to a bill-of-material high pressure compressor. Surge margin also improved 4 percentage points over the high power operating range. A thrust specific fuel consumption improvement of 0.7 percent at typical cruise conditions was calculated based on the sea level test results.
    Keywords: MECHANICAL ENGINEERING
    Type: NASA-CR-165531 , PWA-5515-162
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    Preliminary results on the development of vacuum brazed joints for cryogenic wind tunnel aerofoil models (1981)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: The results of initial experiments show that high-strength void-free bonds can be formed by vacuum brazing of stainless steels using copper and nickel-based filler metals. In Nitronic 40, brazed joints have been formed with strengths in excess of the yield strength of the parent metal, and even at liquid nitrogen temperatures the excellent mechanical properties of the parent metal are only slightly degraded. The poor toughness of 15-5 P.H. stainless steel at cryogenic temperatures is lowered even further by the presence of the brazed bonds investigated. It is highly unlikely that the technique would be used for any critical areas of aerofoil models intended for low-temperature service. Nevertheless, the potential advantages of this simplified method of construction still have attractions for use at ambient temperatures.
    Keywords: MECHANICAL ENGINEERING
    Type: International Cryogenic Materials Conference; Aug 10, 1981 - Aug 14, 1981; San Diego, CA
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    NASA five-ball fatigue tester - Over 20 years of research (1981)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: The paper reviews, from both a technical and historic perspective, the results of research conducted using the NASA Five-Ball Fatigue Tester. The test rig was conceived by W. J. Anderson in late 1958. The first data was generated in March 1959. Since then a total of approximately 500,000 test hours have been accumulated on a group of eight test rigs which are capable of running 24 hours a day, 7 days a week. Studies have been conducted to determine the effect on rolling-element fatigue life of contact angle, material hardness, chemistry, heat treatment, and processing, lubricant type and chemistry, elastohydrodynamic film thickness, deformation and wear, vacuum, and temperature as well as Hertzian and residual stresses. Correlation was established between the results obtained using the five-ball tester and those obtained with full-scale rolling-element bearings.
    Keywords: MECHANICAL ENGINEERING
    Type: International Symposium on Contact Rolling Fatigue Testing of Bearing Steel; May 12, 1981 - May 14, 1981; Phoenix, AZ
    Format: text
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