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  • Other Sources  (195)
  • MECHANICAL ENGINEERING  (195)
  • 1995-1999  (1)
  • 1980-1984  (194)
  • 1996  (1)
  • 1980  (194)
  • 1
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    Gas bearings (1980)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: The present work deals with the fundamentals of gas lubrication theory, which forms the foundation of all analytical design tools for gas bearings. Most of the hard lessons learned in the past are outlined with reference to dry contact, debris ingestion, sliding speed, and chemical stability of lubricant. The mathematical theory of gas lubrication is described for scaling rules in thin-film viscous flow, momentum conservation, mass conservation, energy conservation, isothermal gas bearing theory, coupling effects, and global bearing characteristics. Particular attention is given to the governing differential equations for common bearing configurations. Also discussed are representative solutions of self-acting gas bearings, externally pressurized bearings, and time-dependent effects.
    Keywords: MECHANICAL ENGINEERING
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  • 2
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    Adhesion and friction of single-crystal diamond in contact with transition metals (1980)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: An investigation was conducted to examine the adhesion and friction of single-crystal diamond in contact with various transition metals and the nature of metal transfer to diamond. Sliding friction experiments were conducted with diamond in sliding contact with the metals yttrium, titanium, zirconium, vanadium, iron, cobalt, nickel, tungsten, platinum, rhenium and rhodium. All experiments were conducted with loads of 0.05 to 0.3 N, at a sliding velocity of 0.003 m per minute, in a vacuum of 10 to the -8th Pa, at room temperature, and on the (111) plane of diamond with sliding in the 110 line type direction. The results of the investigation indicate that the coefficient of friction for diamond in contact with various metals is related to the relative chemical activity of the metals in high vacuum. The more active the metal, the higher the coefficient of friction. All the metals examined transferred to the surface of diamond in sliding.
    Keywords: MECHANICAL ENGINEERING
    Type: Applications of Surface Science; 6; 1980
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  • 3
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    Power distribution for electron beam welding (1980)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The power distribution of an electron seam is analyzed. Digital computer techniques are used to evaluate the radial distribution of power detected by a wire probe circulating through the beam. Results are reported.
    Keywords: MECHANICAL ENGINEERING
    Type: Alabama Univ. Res. Rept.: The 1980 NASA(ASEE Summer Fac. Fellowship Program; 31 p
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  • 4
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    Fluid dynamic analysis of the space shuttle main engine high pressure oxidizer turbopump slinger seal (1980)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: The details of the flow on the bladed side of a centrifugal type dynamic shaft seal utilized to contain liquid oxygen in the Space Shuttle Main Engine high pressure oxidizer turbopump were clarified. The governing equations are solved to predict the pressure and temperature gradients and to aid in investigating the nature of the liquid-vapor interface. Recommendations for design improvements are discussed.
    Keywords: MECHANICAL ENGINEERING
    Type: Alabama Univ. Res. Rept.: The 1980 NASA(ASEE Summer Fac. Fellowship Program; 22 p
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  • 5
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    Incipient Failure Detection (IFD) of antifriction ball bearings (1980)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: Two methods were investigated for retrieving the ball bearing signals buried by the overall signature of an operating large engine such as the main space shuttle engine. The signal averaging method averages n** signals over a time duration equaling the known period of the ball bearing defect frequency. With this method, the desired ball bearing defect signal will be enhanced over the noise by a factor of the square root of n. A second method is to perform a further frequency analysis on the logarithmic spectrum in order to detect and separate different families of harmonics and sidebands, thereby giving information about modulating frequencies. These two alternate IFD methods were carried out with a Norland 3001 waveform and data system. The obtained results are then compared with the power spectral density (PSD) of the overall machine signals and conclusions are made accordingly.
    Keywords: MECHANICAL ENGINEERING
    Type: Alabama Univ. Res. Rept.: The 1980 NASA(ASEE Summer Fac. Fellowship Program; 24 p
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  • 6
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    Rolling-element bearings (1980)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: In contrast to hydrodynamic bearings, which depend for low-friction characteristics on a fluid film between the journal and the bearing surfaces, roller-element bearings employ a number of balls or rollers that roll in an annular space. The paper briefly outlines the advantages and disadvantages of roller-element bearings as compared to hydrodynamic bearings. The discussion covers bearing types, rolling friction, friction losses in rolling bearings, contact stresses, deformations, kinematics (normal and high speeds), bearing dynamics including elastohydrodynamics, load distribution, lubrication (grease, solid oil, oil-air mist), specific dynamic capacity and life, specific static capacity, and fatigue or wearout (elastohydrodynamics, wear). Rolling bearing wear factor as a function of operating environment is plotted and discussed.
    Keywords: MECHANICAL ENGINEERING
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  • 7
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    Wear of seal materials used in aircraft propulsion systems (1980)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: A review of various types of seal locations in a gas turbine engine and the significance of wear for each type are presented. Material selection guidelines and the PV (contact pressure times sliding velocity) criteria for seal materials are discussed, and examples of wear mechanisms in positive contact seals are given. It is suggested that improved wear, erosion, and oxidation resistant materials will be required for improved seal durability; finally, a correlation is proposed between wear characteristics and a factor that includes material strength, ductility, specific heat and hot-working temperature to attain low porosity metallic gas path seal materials.
    Keywords: MECHANICAL ENGINEERING
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  • 8
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    Computation of flow in radial- and mixed-flow cascades by an inviscid-viscous interaction method (1980)
    In:  CASI
    Details
    Publication Date: 2017-10-02
    Description: The use of inviscid-viscous interaction methods for the case of radial or mixed-flow cascade diffusers is discussed. A literature review of investigations considering cascade flow-field prediction by inviscid-viscous iterative computation is given. Cascade aerodynamics in the third blade row of a multiple-row radial cascade diffuser are specifically investigated.
    Keywords: MECHANICAL ENGINEERING
    Type: AGARD Centrifugal Compressors, Flow Phenomena and Performance; 11 p
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  • 9
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    Parametric instabilities of rotor-support systems with application to industrial ventilators (1980)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: Rotor support systems interaction with parametric excitation is considered for both unequal principal shaft stiffness (generators) and offset disc rotors (ventilators). Instability regions and types of instability are computed in the first case, and parametric resonances in the second case. Computed and experimental results are compared for laboratory machine models. A field case study of parametric vibrations in industrial ventilators is reported. Computed parametric resonances are confirmed in field measurements, and some industrial failures are explained. Also the dynamic influence and gyroscopic effect of supporting structures are shown and computed.
    Keywords: MECHANICAL ENGINEERING
    Type: NASA. Lewis Res. Center Rotordyn. Instability Probl. in High-Performance Turbomachinery; p 383-400
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  • 10
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    Fluid forces on rotating centrifugal impeller with whirling motion (1980)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: Fluid forces on a centrifugal impeller, whose rotating axis whirls with a constant speed, were calculated by using unsteady potential theory. Calculations were performed for various values of whirl speed, number of impeller blades and angle of blades. Specific examples as well as significant results are given.
    Keywords: MECHANICAL ENGINEERING
    Type: NASA. Lewis Res. Center Rotordyn. Instability Probl. in High-Performance Turbomachinery; p 317-328
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  • 11
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    Non-Synchronous Whirling Due to Fluid-Dynamic Forces in Axial Turbo-Machinery Rotors (1980)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: The role of fluid forces acting on the blades of an axial turborotor with regards to whirling was analyzed. The dynamic equations were formulated for the coning mode of an overhung rotor. The exciting forces due to the motion were defined through a set of rotor stability derivatives, and analytical expressions of the aerodynamic contributions were found for the case of small mean stream deflection, high solidity and equivalent flat plate cascade. For a typical case, only backward whirl was indicated when the phase shifting of the rotor wake effect was ignored. A parametric study of the dynamic stability boundary reveals that a reduction in blade stagger angle, mass flow rate, fluid density and an increase in stiffness and external damping are all inductive for improved stability.
    Keywords: MECHANICAL ENGINEERING
    Type: NASA. Lewis Res. Center Rotordyn. Instability Probl. in High-Performance Turbomachinery; p 267-284
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  • 12
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    Effect of fluid forces on rotor stability of centrifugal compressors and pumps (1980)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: A simple two dimensional model for calculating the rotordynamic effects of the impeller force in centrifugal compressors and pumps is presented. It is based on potential flow theory with singularities. Equivalent stiffness and damping coefficients are calculated for a machine with a vaneless volute formed as a logarithmic spiral. It is shown that for certain operating conditions, the impeller force has a destablizing effect on the rotor.
    Keywords: MECHANICAL ENGINEERING
    Type: NASA. Lewis Res. Center Rotordyn. Instability Probl. in High-Performance Turbomachinery; p 249-265
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  • 13
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    Experimental results concerning centrifugal impeller excitations (1980)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: The effect of working fluid on the dynamics of an impeller with radial vanes was investigated. The impeller was supported vertically from a very flexible quill shaft in order to produce a low critical speed, and to allow the fluid dynamic effects on the impeller to predominate. The shaft was supported from ball bearings, so that there was no possibility of oil whip from fluid film bearings as a destabilizing influence. The impeller was run both in the atmosphere, and submerged in working fluids contained in a cylindrical housing, open at the top. Variable speed was obtained with a dc gearmotor drive unit. The speed was measured with a proximity probe pulse tachometer and electronic digital counter.
    Keywords: MECHANICAL ENGINEERING
    Type: NASA. Lewis Res. Center Rotordyn. Instability Probl. in High-Performance Turbomachinery; p 361-367
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  • 14
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    Limit cycles of a flexible shaft with hydrodynamic journal bearings in unstable regimes (1980)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: A symmetric 3 mass rotor supported on hydrodynamic bearings is described. An approximate method of representing finite bearings is used to calculate bearing forces. As the method sums forces from a number of independent circular lobes lemon 3 and 4 lobe bearings are taken into account. The calculations are based on an axial groove bearing. Linear analysis precedes nonlinear simulation of some unstable conditions. The demonstration of small limit cycles suggests that necessarily flexible rotors e.g., helicopter tail rotors, may be practical without either tilt pad bearings or external dampers.
    Keywords: MECHANICAL ENGINEERING
    Type: NASA. Lewis Res. Center Rotordyn. Instability Probl. in High-Performance Turbomachinery; p 331-343
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  • 15
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    Asynchronous vibration problem of centrifugal compressor (1980)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: An unstable asynchronous vibration problem in a high pressure centrifugal compressor and the remedial actions against it are described. Asynchronous vibration of the compressor took place when the discharge pressure (Pd) was increased, after the rotor was already at full speed. The typical spectral data of the shaft vibration indicate that as the pressure Pd increases, pre-unstable vibration appears and becomes larger, and large unstable asynchronous vibration occurs suddenly (Pd = 5.49MPa). A computer program was used which calculated the logarithmic decrement and the damped natural frequency of the rotor bearing systems. The analysis of the log-decrement is concluded to be effective in preventing unstable vibration in both the design stage and remedial actions.
    Keywords: MECHANICAL ENGINEERING
    Type: NASA. Lewis Res. Center Rotordyn. Instability Probl. in High-Performance Turbomachinery; p 109-118
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  • 16
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    Analysis and identification of subsynchronous vibration for a high pressure parallel flow centrifugal compressor (1980)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: The summary of a complete analytical design evaluation of an existing parallel flow compressor is presented and a field vibration problem that manifested itself as a subsynchronous vibration that tracked at approximately 2/3 of compressor speed is reviewed. The comparison of predicted and observed peak response speeds, frequency spectrum content, and the performance of the bearing-seal systems are presented as the events of the field problem are reviewed. Conclusions and recommendations are made as to the degree of accuracy of the analytical techniques used to evaluate the compressor design.
    Keywords: MECHANICAL ENGINEERING
    Type: NASA. Lewis Res. Center Rotordyn. Instability Probl. in High-Performance Turbomachinery; p 45-63
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  • 17
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    Use of cryopumps on large space simulation systems (1980)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: The need for clean, oil free space simulation systems has demanded the development of large, clean pumping systems. The assurance of optically dense liquid nitrogen baffles over diffusion pumps prevents backstreaming to a large extent, but does not preclude contamination from accidents or a control failure. Turbomolecular pumps or ion pumps achieve oil free systems but are only practical for relatively small chambers. Large cryopumps were developed and checked out which do achieve clean pumping of very large chambers. These pumps can be used as the original pumping system or can be retrofitted as a replacement for existing diffusion pumps.
    Keywords: MECHANICAL ENGINEERING
    Type: NASA. Johnson Space Center The 11th Space Simulation Conf.; p 71-78
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  • 18
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    On the role of oil-film bearings in promoting shaft instability: Some experimental observations (1980)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: The occurrence of oil whirl instability in rigid and flexible rotor systems was investigated. The effect of various bearing parameters on the oil whirl frequency and amplitude of rigid and flexible shafts supported on fluid film bearings was also studied.
    Keywords: MECHANICAL ENGINEERING
    Type: NASA. Lewis Res. Center Rotordyn. Instability Probl. in High-Performance Turbomachinery; p 345-357
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  • 19
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    Vibration exciting mechanisms induced by flow in turbomachine stages (1980)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: The quasisteady computer analysis of the perturbated centrifugal impeller passage flow was reviewed. A total of 115 stage calculations were used to define the fluid damping coefficient, delta sub fluid. Results indicate that the average total damping coefficient per stage needed for stability is delta sub total 1.85.
    Keywords: MECHANICAL ENGINEERING
    Type: NASA. Lewis Res. Center Rotordyn. Instability Probl. in High-Performance Turbomachinery p285-302 (SEE N80-29706 20-37)
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  • 20
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    Hydraulic forces caused by annular pressure seals in centrifugal pumps (1980)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: The hydraulic forces caused by annular pressure seals were investigated. The measured inlet and exit loss coefficients of the flow through the seals were much smaller than the conventional values. The results indicate that the damping coefficient and the inertia coefficient of the fluid film in the seal are not affected much by the rotational speed or the eccentricity of the rotor, though the stiffness coefficient seemed to be influenced by the eccentricity.
    Keywords: MECHANICAL ENGINEERING
    Type: NASA. Lewis Res. Center Rotordyn. Instability Probl. in High-Performance Turbomachinery p213-225 (SEE N80-29706 20-37)
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  • 21
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    Damping in ring seals for compressible fluids (1980)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: An analysis is presented to calculate damping in ring seals for a compressible fluid. Results show that damping in tapered ring seals (optimized for stiffness) is less than that in straight bore ring seals for the same minimum clearance. Damping in ring seals can promote fractional frequency whirl and can, thus, be detrimental. Thus, tapered seals can benefit rotor and seal stability by having lower damping as well as higher stiffness. Use of incompressible results leads to large errors.
    Keywords: MECHANICAL ENGINEERING
    Type: Rotordyn. Instability Probl. in High-Performance Turbomachinery; p 169-188
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  • 22
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    Field verification of lateral-torsional coupling effects on rotor instabilities in centrifugal compressors (1980)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: Lateral and torsional vibration data obtained on a centrifugal compressor train which had shaft instabilities and gear failures is examined. The field data verifies that the stability of centrifugal compressors can be adversely affected by coincidence of torsional natural frequencies with lateral instability frequencies. The data also indicates that excitation energy from gear boxes can reduce stability margins if energy is transmitted either laterally or torsionally to the compressors. The lateral and torsional coupling mechanisms of shaft systems is discussed. The coupling mechanisms in a large industrial compressor train are documented and the potential effect on rotor stability is demonstrated. Guidelines are set forth to eliminate these potential problems by minimizing the interaction of torsional and lateral responses and their effect on rotor stability.
    Keywords: MECHANICAL ENGINEERING
    Type: NASA. Lewis Res. Center Rotordyn. Instability Probl. in High-Performance Turbomachinery; p 15-34
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  • 23
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    Triple-axis common-pivot arm wrist device for manipulative applications (1980)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: A concept in manipulator development to overcome the 'weak wrist syndrome', a triple-axis common-pivot arm wrist (TACPAW), is presented. It contains torque motors for actuation, tachometers for measuring rate, and resolvers for position measurements. Furthermore, it provides three degrees of freedom, i.e., pitch, yaw, and roll, in a single manipulator joint. The advantages of this development are increased strength, compactness, and simplification of controls. Designed to be compatible with the protoflight manipulator arm, the joints of TACPAW are back-driveable with + or - 45 deg rotation in pitch, + or - 45 deg in yaw and continuous roll in either direction while delivering 20.5 N-m (15 ft-lb) torque in each of the three movements.
    Keywords: MECHANICAL ENGINEERING
    Type: NASA. Langley Res. Center Proc. of the 14th Aerospace Mech. Symp.; p 111-124
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  • 24
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    Mechanisms of UK radiometers flown on Nimbus 5 and 6 with particular reference to bearings, pivots and lubrication (1980)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: The mechanisms incorporated in the vertical sounding infrared radiometry experiments which were launched on Nimbus 5 in 1972 and on Nimbus 6 in 1975 are discussed. Both use dry lubricants. The Nimbus 5 radiometer includes a rotating chopper driven via a carbon fiber-acetal resin gearwheel. The driving motor runs at 2000 rpm and has completed over 7 x 10 to the 9th power revolutions. Four gear driven filter wheels powered by stepper motors have each completed 2 x 10 to the 8th power changes. The input calibration mirror mechanism and its field of view compensation mechanisms are also described. All 25 ball races used in the experiment are of the film transfer type. The Nimbus 6 radiometer includes two cells. Each contains a piston supported on diaphragm springs and driven electromagnetically. The pistons are 6 cm in diameter with a stroke of 1 cm and are driven at their mechanical resonant frequency of approx. 15 Hz. The calibrating mirrors rotate periodically to view a target. The support pivots are synthetic sapphire ring stones with separate end thrust stones. The problems of mounting these stones to withstand vibration loads is described.
    Keywords: MECHANICAL ENGINEERING
    Type: NASA. Langley Res. Center Proc. of the 14th Aerospace Mech. Symp.; p 101-110
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  • 25
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    Centrifugal regulator for control of deployment rates of deployable elements (1980)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: The requirements, design, and performance of a centrifugal regulator aimed at limiting deployment rates of deployable elements are discussed. The overall mechanism is comprised of four distinct functional parts in a machined housing: (1) the centrifugal brake device, which checks the payout of a deployment cable; (2) the reducing gear, which produces the spin rate necesary for the braking device; (3) the payout device, which allows the unwinding of the cable; and (4) the locking device, which prevents untimely unwinding. The centrifugal regulator is set into operation by a threshold tension of the cable which unlocks the mechanism and allows unwinding. The pulley of the windout device drives the centrifugal brake with the help of the reducing gear. The centrifugal force pushes aside weights that produce friction of the studs in a cylindrical housing. The mechanism behaved well at qualification temperature and vibrations.
    Keywords: MECHANICAL ENGINEERING
    Type: NASA. Langley Res. Center Proc. of the 14th Aerospace Mech. Symp.; p 93-99
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  • 26
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    The Magsat magnetometer boom (1980)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: A lightweight extendable structure that can precisely position magnetically sensitive instruments safe distances from magnetic sources in a spacecraft is described as well as the major areas of concern that played dominant roles in its development. Weight, packaging volume, thermal distortion, mechanical misalignments, dimensional instability, launch environments, and low temperature functioning were areas that presented some formidable obstacles. The ways in which these obstacles were dealt with are examined for those involving the development of similar aerospace mechanisms with equally restrictive requirements.
    Keywords: MECHANICAL ENGINEERING
    Type: NASA. Langley Res. Center Proc. of the 14th Aerospace Mech. Symp.; p 267-278
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  • 27
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    Orbiter door closure tools (1980)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: Safe reentry of the shuttle orbiter requires that the payload bay doors be closed and securely latched. Since a malfunction in the door drive or bulkhead latch systems could make safe reentry impossible, the requirement to provide tools to manually close and secure the doors was implemented. The tools would disconnect a disabled door or latch closure system and close and secure the doors if the normal system failed. The tools required to perform these tasks have evolved into a set that consists of a tubing cutter, a winch, a latching tool, and a bolt extractor. The design, fabrication, and performance tests of each tool are described.
    Keywords: MECHANICAL ENGINEERING
    Type: NASA. Langley Res. Center Proc. of the 14th Aerospace Mech. Symp.; p 19-31
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  • 28
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    The Eccentuator: A new concept in actuation (1980)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: A new concept in actuation for aerospace mechanisms is presented. This actuator, called an 'eccentuator', features unique output characteristics, installation and envelope efficiencies, and relative simplicity. The actuator can be powered by either hydraulic or mechanical inputs. Potential applications of the 'eccentuator' and development efforts are discussed.
    Keywords: MECHANICAL ENGINEERING
    Type: NASA. Langley Res. Center Proc. of the 14th Aerospace Mech. Symp.; p 57-67
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  • 29
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    The actuated latch pin and its development (1980)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: An actuated latch pin developed to meet the need for a reusable locking device is described. The unit can function as a pin puller or as a pin pusher latch. Initial prototype testing demonstrated the feasibility of the device with the unit being driven from a 28 V dc supply and using 15 W to drive a 12 mm diameter pin through a stroke of 10 mm with a side load of 100 N in 120 ms. High wear rates with a MOS2 lubrication on the ballscrew and angular contact bearings have necessitated the reduction in the duty cycle from 1000 cycles in air and vacuum to 100 in air and 1000 in vacuum.
    Keywords: MECHANICAL ENGINEERING
    Type: NASA. Langley Res. Center Proc. of the 14th Aerospace Mech. Symp.; p 69-78
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  • 30
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    Use of elastomeric elements in control of rotor instability (1980)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: The dynamic characteristics of elastomeric supports are discussed. Stiffness and damping characteristics for elastomers of various geometries including O-rings, buttons loaded in compression, and rectangular elements loaded in shear are presented. The effects of frequency, temperature, and amplitude are illustrated, as well as the effects of material and geometry. Empirical design methods are illustrated, and several examples are presented where elastomers have successfully controlled both synchronous and nonsynchronous vibrations.
    Keywords: MECHANICAL ENGINEERING
    Type: NASA. Lewis Res. Center Rotordyn. Instability Probl. in High-Performance Turbomachinery p453-465 (SEE N80-29706 20-37)
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  • 31
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    Physical explanations of the destabilizing effect of damping in rotating parts (1980)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: The destabilizing effect of rotating damping was investigated. When the rotation was faster than the whirl, rotating damping drags the orbiting particle forward. When stationary damping was also present, the stability borderline was readily determined by balancing the backward and forward drags. A key notion was that a forward whirl at rate omega a sub n with respect to stationary axes appears to be a backward whirl at rate Omega - omega sub n with respect to a system rotating supercritically at rate Omega. The growth rate of unstable whirls (or the decay rate of stable whirls was readily estimated by a simple energy balance.
    Keywords: MECHANICAL ENGINEERING
    Type: NASA. Lewis Res. Center Rotordyn. Instability Probl. in High-Performance Turbomachinery p369-382 (SEE N80-29706 20-37)
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  • 32
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    Self-excited rotor whirl due to tip-seal leakage forces (1980)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: The limitations in the performance of turbomachines which arise as a result of selfexcited vibration were investigated. Bearing forces, elastic hysteresis, and forces from fluid flow through clearances were considered as possible origins. A theoretical evaluation was made to determine the dependence of the forces form the leakage losses and from rotating flow in radial gaps.
    Keywords: MECHANICAL ENGINEERING
    Type: NASA. Lewis Res. Center Rotordyn. Instability Probl. in High-Performance Turbomachinery p303-316 (SEE N80-29706 20-37)
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  • 33
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    Flow Induced Spring Coefficients of Labyrinth Seals for Application in Rotor Dynamics (1980)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: Flow induced aerodynamic spring coefficients of labyrinth seals are discussed and the restoring force in the deflection plane of the rotor and the lateral force acting perpendicularly to it are also considered. The effects of operational conditions on the spring characteristics of these components are examined, such as differential pressure, speed, inlet flow conditions, and the geometry of the labyrinth seals. Estimation formulas for the lateral forces due to shaft rotation and inlet swirl, which are developed through experiments, are presented. The utilization of the investigations is explained and results of stability calculations, especially for high pressure centrifugal compressors, are added. Suggestions are made concerning the avoidance of exciting forces in labyrinths.
    Keywords: MECHANICAL ENGINEERING
    Type: NASA. Lewis Res. Center Rotodyn. Instability Probl. in High-Performance Turbomachinery; p 189-212
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  • 34
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    Evaluation of instability forces of labyrinth seals in turbines or compressors (1980)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: The effects of a force induced by the labyrinth seal on the stability of rotor systems and the factors of the seal which affect the stability are investigated. In the analysis, it is assumed that the fluid in the seal is steady and that the rotor is set vertically in order to avoid the effects of gravity force. The force induced by the seal is expressed in terms proportional to the velocity and displacement of the rotor and is deduced to that expression for the oil film force in journal bearings. That force is taken into account in the equations of motion; then the stability of the system is discussed by energy concept. The force induced by the labyrinth seal always makes the rotor system unstable, and the tendency is marked when seal leakages are small. The resonance point of the rotor system is also affected by the labyrinth seal (the resonance point of the rotor system is removed by the seal leakages). The force induced by the labyrinth seal was measured by using a water-tunnel experimental system which was designed to measure the labyrinth seal force by using the similarity between gas and liquid flow theory.
    Keywords: MECHANICAL ENGINEERING
    Type: NASA. Lewis Res. Center Rotordyn. Instability Probl. in High-Performance Turbomachinery p139-167 (SEE N80-29706 20-37)
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  • 35
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    The parameters and measurements of the destabilizing actions of rotating machines, and the assumptions of the 1950's (1980)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: The measurability of destabilizing actions is demonstrated for a rotor built to produce a forward circular, self excited malfunction (gas whip). It is argued that the continued use of past modeling technqiues is unfortunate in that it has led to the use of inappropriate words to express what is happening and a lack of full understanding of the category of forward circular whip instability mechanisms.
    Keywords: MECHANICAL ENGINEERING
    Type: NASA. Lewis Res. Center Rotordyn. Instability Probl. in High-Performance Turbomachinery p95-106 (SEE N80-29706 20-37)
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  • 36
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    Field experiences with rotordynamic instability in high-performance turbomachinery (1980)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: Two field situations illustrate the consequences of rotordynamic instability in centrifugal compressors. One involves the reinjection of produced gas into a North Sea oil formation for the temporary extraction of crude. The other describes on-shore compressors used to deliver natural gas from off-shore wells. The problems which developed and the remedies attempted in each case are discussed. Instability problems resulted in lost production, extended construction periods and costs, and heavy maintenance expenditures. The need for effective methods to properly identify the problem in the field and in the compressor design stage is emphasized.
    Keywords: MECHANICAL ENGINEERING
    Type: NASA. Lewis Res. Center Rotordyn. Instability Probl. in High-Performance Turbomachinery; p 3-13
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  • 37
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    The design and application of an antenna positioner mechanism for Intelsat-5 series communication satellite (1980)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: In opertion, the East/West spot beam reflectors on the Intelsat-5 series communication satellite are required to satisfy initial precise-pointing to particular Earth locations; and repositioning and pointing to different Earth locations as traffic changes dictate during the seven year mission. Two 2 axis antenna positioner mechanisms (APM) are utilized in fulfilling these requirements. Each APM is comprised of three components which consist of one center pivot and two linear actuators rather than an integral two axis gimbal design. The step resolution of the APM can be adjusted as required with the present design, at a step resolution of 0.002865 degrees. The design philosophy and considerations, test program, and test results are discussed as well as some major problems encountered during the course of testing and their resolution.
    Keywords: MECHANICAL ENGINEERING
    Type: NASA. Langley Res. Center Proc. of the 14th Aerospace Mech. Symp.; p 311-322
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  • 38
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    Ku band deployed assembly and gimbal (1980)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: Requirements for shuttle orbiter missions to locate satellites for servicing and to communicate when out of touch with a direct ground link were established. A Ku Band deployed antenna system providing an integrated radar and communications function was designed to meet these requirements. The unique features of the gimbal assembly are described with emphasis on the following: edge mounted antenna to minimize stowage volume in shuttle and maximize gain; unique two axis housing and shaft arrangement to accommodate two runs of waveguide and 55 electrical conductors without requiring slip rings; maximum use of aluminum in gimbal structure to reduce costs; and lubricant chosen to survive Earth and space environments.
    Keywords: MECHANICAL ENGINEERING
    Type: NASA. Langley Res. Center Proc. of the 14th Aerospace Mech. Symp.; p 163-172
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  • 39
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    Unknown
    Automated beam builder (1980)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: Requirements for the space fabrication of large space structures are considered with emphasis on the design, development, manufacture, and testing of a machine which automatically produces a basic building block aluminum beam. Particular problems discussed include those associated with beam cap forming; brace storage, dispensing, and transporting; beam component fastening; and beam cut-off. Various critical process tests conducted to develop technology for a machine to produce composite beams are also discussed.
    Keywords: MECHANICAL ENGINEERING
    Type: NASA. Langley Res. Center Proc. of the 14th Aerospace Mech. Symp.; p 247-265
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  • 40
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    Unknown
    A mechanical adapter for installing mission equipment on large space structures (1980)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: A mechanical attachment adapter was designed, constructed, and tested. The adapter was was included in a simulation program that investigated techniques for assembling erectable structures under simulated zero-g conditions by pressure-suited subjects in a simulated EVA mode. The adapter was utilized as an interface attachment between a simulated equipment module and one node point of a tetrahedral structural cell. The mating performance of the adapter, a self-energized mechanism, was easily and quickly demonstrated and required little effort on the part of the test subjects.
    Keywords: MECHANICAL ENGINEERING
    Type: NASA. Langley Res. Center Proc. of the 14th Aerospace Mech. Symp.; p 237-245
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  • 41
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    A precision bearing gimbal system for the Teal Ruby program (1980)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: A precision bearing gimbal system designed to allow a spaceborne infrared sensor to stare at points on the Earth while in orbit is described. The problems encountered, analytical tools and test methods used, and data applicable to users of similar systems are presented. Assembly procedures, bearing preload effects, moisture control, structural analysis, and noise control are specifically examined.
    Keywords: MECHANICAL ENGINEERING
    Type: NASA. Langley Res. Center Proc. of the 14th Aerospace Mech. Symp.; p 143-153
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  • 42
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    Fuel/hydraulic transfer valve improves reliability of Atlas space launch vehicle (1980)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: The Atlas fuel hydraulic transfer valve design is described. The design satisfies primary goals such as fuel and oil isolation before launch in order to use existing ground support and airborne hardware and procedures. The valve operates only after the vehicle has been committed to launch. Hydraulic system function is maintained if the valve fails to function. Valve operation is mechanical and interfaces only with the propulsion system.
    Keywords: MECHANICAL ENGINEERING
    Type: NASA. Langley Res. Center Proc. of the 14th Aerospace Mech. Symp.; p 155-161
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  • 43
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    The mechanisms of the SAMS experiment flown on Nimbus 7 with particular reference to the 2 axis scanning mirror (1980)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: The stratospheric and mesospheric sounder (SAMS) experiment on Nimbus 7 includes a 2 axis scanning mirror and 7 pressure modulator cells. The SAMS experiment is a limb sounding instrument to measure the temperature profile and minor constituents of the atmosphere. The limb scan requires small mirror steps over a 3 deg range, while the scan in azimuth is in larger steps over a 15 deg range. The mirror is plane, 20 cm in diameter, and of zero expansion glass-ceramic. It is supported on two tilt tables, fitted one on the other, with the axes at right angles. The angle of tilt is adjusted by means of recirculating ball screws which are ion plated with lead for lubrication and driven by stepper motors. The seven gas filled cells are each pressure modulated by a 3 cm diameter, 0.3 cm stroke piston which is supported by diaphragm springs and driven electromagnetically at the system's mechanical resonant frequency. The mean pressure of the filling gas, which is the atmospheric constituent being measured, is changed by varying the temperature of a suitable molecular sieve.
    Keywords: MECHANICAL ENGINEERING
    Type: NASA. Langley Res. Center Proc. of the 14th Aerospace Mech. Symp.; p 323-333
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  • 44
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    Ball bearing versus magnetic bearing reaction and momentum wheels as momentum actuators (1980)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: Different bearing technologies of momentum actuators for the attitude control of satellites are compared and a guideline for the selection of the suitable momentum actuators or momentum actuator configurations to meet given mission goals with high reliability and low cost is developed. The comparison between ball bearing and magnetic bearing momentum actuators shows that given mission requirements can be economically met by employing the ball bearing technology without decreasing reliability and lifetime. However, for some special mission requirements, such as 'zero friction at zero speed,' fine pointing (met by vernier gimballing), and/or active damping, magnetic bearings may be advantageous. This makes it evident that magnetic bearing technology will not replace ball bearing technology for momentum actuators, but will supplement it for some special mission requirements.
    Keywords: MECHANICAL ENGINEERING
    Type: NASA. Langley Res. Center Proc. of the 14th Aerospace Mech. Symp.; p 79-91
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  • 45
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    Subsynchronous instability of a geared centrifugal compressor of overhung design (1980)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: The original design analysis and shop test data are presented for a three stage (poster) air compressor with impellers mounted on the extensions of a twin pinion gear, and driven by an 8000 hp synchronous motor. Also included are field test data, subsequent rotor dynamics analysis, modifications, and final rotor behavior. A subsynchronous instability existed on a geared, overhung rotor. State-of-the-art rotor dynamics analysis techniques provided a reasonable analytical model of the rotor. A bearing modification arrived at analytically eliminated the instability.
    Keywords: MECHANICAL ENGINEERING
    Type: NASA. Lewis Res. Center Rotordyn. Instability Probl. in High-Performance Turbomachinery; p 67-83
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  • 46
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    Practical experience with unstable compressors (1980)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: Using analytical mathematical modeling techniques for the system components, an attempt is made to gauge the destabilizing effects in a number of compressor designs. In particular the overhung (or cantilevered) compressor designs and the straddle-mounted (or simply supported) compressor designs are examined. Recommendations are made, based on experiences with stable and unstable compressors, which can be used as guides in future designs. High and low pressure compressors which operate well above their fundamental rotor-bearing lateral natural frequencies can suffer from destructive subsynchronous vibration. Usually the elements in the system design which contribute to this vibration, other than the shafting and the bearings, are the seals (both gas labyrinth and oil breakdown bushings) and the aerodynamic components.
    Keywords: MECHANICAL ENGINEERING
    Type: NASA. Lewis Res. Center Rotordyn. Instability Probl. in High-Performance Turbomachinery p35-43 (SEE N80-29706 20-37)
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  • 47
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    The reverse laser drilling of transparent materials (1980)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: Within a limited range of incident laser-beam intensities, laser drilling of a sapphire wafer initiates on the surface of the wafer where the laser beam exits and proceeds upstream in the laser beam to the surface where the laser beam enters the wafer. This reverse laser drilling is the result of the constructive interference between the laser beam and its reflected component on the exit face of the wafer. Constructive interference occurs only at the exit face of the sapphire wafer because the internally reflected laser beam suffers no phase change there. A model describing reverse laser drilling predicts the ranges of incident laser-beam intensity where no drilling, reverse laser drilling, and forward laser drilling can be expected in various materials. The application of reverse laser drilling in fabricating feed-through conductors in silicon-on-sapphire wafers for a massively parallel processer is described.
    Keywords: MECHANICAL ENGINEERING
    Type: Journal of Applied Physics; 51; Nov. 198
    Format: text
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  • 48
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    Development of assembly and joint concepts for erectable space structures (1980)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: The technology associated with the on-orbit assembly of tetrahedral truss platforms erected of graphite epoxy tapered columns is examined. Associated with the assembly process is the design and fabrication of nine member node joints. Two such joints demonstrating somewhat different technology were designed and fabricated. Two methods of automatic assembly using the node designs were investigated, and the time of assembly of tetrahedral truss structures up to 1 square km in size was estimated. The effect of column and node joint packaging on the Space Shuttle cargo bay is examined. A brief discussion is included of operating cost considerations and the selection of energy sources. Consideration was given to the design assembly machines from 5 m to 20 m. The smaller machines, mounted on the Space Shuttle, are deployable and restowable. They provide a means of demonstrating the capabilities of the concept and of erecting small specialized platforms on relatively short notice.
    Keywords: MECHANICAL ENGINEERING
    Type: NASA-CR-3131
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  • 49
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    Device for coupling a first vehicle to a second vehicle (1980)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: A device is disclosed, carried by a first vehicle such as an orbiting space shuttle, having a plurality of contact members for engaging and holding an annular ring on a second vehicle such as an orbiting payload. The contact members are connected to manipulator arms which are mounted at a fulcrum point and which are moved by an iris type mechanism. Movement of the manipulator arms causes the contact members to grasp or release the annular ring. Bumper devices are provided to axially align the annular ring and draw the contact members into engagement therewith.
    Keywords: MECHANICAL ENGINEERING
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  • 50
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    Computer program documentation for the dynamic analysis of a noncontacting mechanical face seal (1980)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: A computer program is presented which achieves a numerical solution for the equations of motion of a noncontacting mechanical face seal. The flexibly-mounted primary seal ring motion is expressed by a set of second order differential equations for three degrees of freedom. These equations are reduced to a set of first order equations and the GEAR software package is used to solve the set of first order equations. Program input includes seal design parameters and seal operating conditions. Output from the program includes velocities and displacements of the seal ring about the axis of an inertial reference system. One example problem is described.
    Keywords: MECHANICAL ENGINEERING
    Type: NASA-TM-81636 , E-650
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  • 51
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    Pressure control valve (1980)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: A control valve is provided which is adapted to be connected between a pressure source, such as a vacuum pump, and a pressure vessel so as to control the pressure in the vessel. The valve comprises a housing having a longitudinal bore which is connected between the pump and vessel, and a transversely movable valve body which controls the air flow through an air inlet in the housing. The valve body includes cylindrical and conical shaped portions which cooperate with reciprocally shaped portions of the housing to provide flow control. A filter in the air inlet removes foreign matter from the air. The bottom end of the valve body is screwed into the valve housing control knob formed integrally with the valve body and controls translation of the valve body, and the opening and closing of the valve.
    Keywords: MECHANICAL ENGINEERING
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  • 52
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    Phase-angle controller for Stirling engines (1980)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: An actuator includes a restraint link adapted to be connected with a pivotal carrier arm for a force transfer gear interposed between the crankshaft for an expander portion of a Stirling engine and a crankshaft for the displacer portion of the engine. The restraint link is releasably trapped hydraulic fluid for selectively establishing a phase angle relationship between the crankshaft. A second embodiment incorporates a hydraulic coupler for use in varying the phase angle of gear-coupled crank fpr a Stirling engine whereby phase angle changes are obtainable.
    Keywords: MECHANICAL ENGINEERING
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  • 53
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    Computer-aided roll pass design in rolling of airfoil shapes (1980)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: This paper describes two computer-aided design (CAD) programs developed for modeling the shape rolling process for airfoil sections. The first program, SHPROL, uses a modular upper-bound method of analysis and predicts the lateral spread, elongation, and roll torque. The second program, ROLPAS, predicts the stresses, roll separating force, the roll torque and the details of metal flow by simulating the rolling process, using the slab method of analysis. ROLPAS is an interactive program; it offers graphic display capabilities and allows the user to interact with the computer via a keyboard, CRT, and a light pen. The accuracy of the computerized models was evaluated by (a) rolling a selected airfoil shape at room temperature from 1018 steel and isothermally at high temperature from Ti-6Al-4V, and (b) comparing the experimental results with computer predictions. The comparisons indicated that the CAD systems, described here, are useful for practical engineering purposes and can be utilized in roll pass design and analysis for airfoil and similar shapes.
    Keywords: MECHANICAL ENGINEERING
    Type: Journal of Applied Metalworking; 1; July 198
    Format: text
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  • 54
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    Speed control device for a heavy duty shaft (1980)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: A speed control device is characterized by a reference speed shaft spatially related to a heavy duty shaft, a drive train for driving the reference speed shaft at a constant angular velocity, a drive train for driving the heavy duty shaft at a variable angular velocity and a speed control assembly for continuously comparing the angular velocity of the heavy duty shaft with the angular velocity of the reference speed shaft. A brake assembly is connected to the heavy duty shaft and is adapted to respond to errors in the angular velocity of the heavy duty shaft in order to reduce the angular velocity of the heavy duty shaft to that of the reference speed shaft.
    Keywords: MECHANICAL ENGINEERING
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  • 55
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    Thermal barrier pressure seal (1980)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: An apparatus is described for providing thermal and pressure sealing in an elongated space of varying width between adjacent surface of two members. The apparatus is mounted for at least limited lateral movement between the members and may comprise: an elongated support attached to one of the adjacent surfaces; a second elongated support member attached to the other of the adjacent surfaces, and an elongated seal member sandwiched between the first and second support members. In its non-deformed state, the elongated seal member may be substantially cylindrical but capable of deformation to accommodate limited lateral movement between the adjacent surfaces and varying widths of the space.
    Keywords: MECHANICAL ENGINEERING
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  • 56
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    Comparisons of modified Vasco X-2 and AISI 9310 gear steels (1980)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Endurance tests were conducted with four groups of spur gears manufactured from three heats of consumable electrode vacuum melted (CVM) modified Vasco X-2. Endurance tests were also conducted with gears manufactured from CVM AISI 9310. Bench type rolling element fatigue tests were conducted with both materials. Hardness measurements were made to 811 K. There was no statistically significant life difference between the two materials. Life differences between the different heats of modified Vasco X-2 can be attributed to heat treat variation and resultant hardness. Carburization of gear flanks only can eliminate tooth fracture as a primary failure mode for modified Vasco X-2. However, a tooth surface fatigue spall can act as a nucleus of a tooth fracture failure for the modified Vasco X-2.
    Keywords: MECHANICAL ENGINEERING
    Type: NASA-TP-1731 , E-070
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  • 57
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    Development of procedures for calculating stiffness and damping of elastomers in engineering applications, part 7 (1980)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: An elastomer shear damper was designed, tested, and compared with the performance of the T 55 power turbine supported on the production engine roller bearing support. The Viton 70 shear damper was designed so that the elastomer damper could be interchanged with the production T 55 power turbine roller bearing support. The results show that the elastomer sheer dampener permitted stable operation of the power turbine to the maximum operating speed of 16,000 rpm.
    Keywords: MECHANICAL ENGINEERING
    Type: NASA-CR-165138 , REPT-80TR63
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  • 58
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    Small passenger car transmission test; Chevrolet LUV transmission (1980)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: A 1978 Chevrolet LUV manual transmission tested per the applicable portions of a passenger car automatic transmission test code (SAE J65lb) which required drive performance, coast performance, and no load test conditions. Under these test conditions, the transmission attained maximum efficiencies in the upper ninety percent range for both drive performance tests and coast performance tests. The major results of this test (torque, speed, and efficiency curves) are presented. Graphs map the complete performance characteristics for the Chevrolet LUV transmission.
    Keywords: MECHANICAL ENGINEERING
    Type: NASA-CR-159882 , ERC-LIB-80121 , DOE/NASA/0124-3
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  • 59
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    Small passenger car transmission test; Ford C4 transmission (1980)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: A 1979 Ford C4 automatic transmission was tested per a passenger car automatic transmission test code (SAE J651b) which required drive performance, coast performance, and no load test conditions. Under these test conditions, the transmission attained maximum efficiencies in the mid-eighty percent range for both drive performance tests and coast performance tests. The major results of this test (torque, speed, and efficiency curves) are presented. Graphs map the complete performance characteristics for the Ford C4 transmission.
    Keywords: MECHANICAL ENGINEERING
    Type: NASA-CR-159881 , ERC-LIB-8060 , DOE/NASA/0124-2
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  • 60
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    SSME turbopump bearing analytical study (1980)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: Three shuttle pump bearings operating under severe overspeed and shut-down conditions are evaluated. The specific parameters investigated include outer race stresses, cage stresses, cage-race drag, bearing heating, and crush loading. A quasi-dynamic version of the BASDAP computer code was utilized which involved the calculation of ball-race forces (inner and outer), contact pressures, contact dimensions, and contact angles as a function of (1) axial load, (2) radial load, and (3) centrifugal load on the bearing. Generally, radial loads on the order of 13,300 N (3000 pounds) per bearing or 26,700 N (6000 pounds) per bearing pair, could be expected to cause severe problems to any of the bearings with a 17,800 N (4000 pounds) axial load. Further, when possible temperature excursions are considered, even a load of 8900 N (2000 pounds) may be excessive. However, high momentary radial loads with a 3800 N (850 pounds) axial load would not be anticipated to cause catastrophic failure of the fuel pump bearing.
    Keywords: MECHANICAL ENGINEERING
    Type: NASA-CR-161554
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    Free-piston regenerative hot gas hydraulic engine (1980)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: A displacer piston which is driven pneumatically by a high-pressure or low-pressure gas is included in a free-piston regenerative hydraulic engine. Actuation of the displacer piston circulates the working fluid through a heater, a regenerator and a cooler. The present invention includes an inertial mass such as a piston or a hydraulic fluid column to effectively store and supply energy during portions of the cycle. Power is transmitted from the working fluid to a hydraulic fluid across a diaphragm or lightweight piston to achieve a hydraulic power out-put. The displacer piston of the present invention may be driven pneumatically, hydraulically or electromagnetically. In addition, the displacer piston and the inertial mass of the present invention may be positioned on the same side of the diaphragm member or may be separated by the diaphragm member.
    Keywords: MECHANICAL ENGINEERING
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  • 62
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    A propulsion system for the Mars rover vehicle (1980)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: The vehicle control electronics for the Mars rover vehicle is described. A functional description of the electronics and its place in the entire system is given. The hardware involved is described from a user's point of view. Changes and additions to the software are included.
    Keywords: MECHANICAL ENGINEERING
    Type: NASA-CR-163494 , RPI-TR-MP-70
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  • 63
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    A propulsion and steering control system for the Mars rover (1980)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: The design of a propulsion and steering control system for the Rensselaer Polytechnic Institute prototype autonomous Mars roving vehicle is presented. The vehicle is propelled and steered by four independent electric motors. The control system must regulate the speeds of the motors so they work in unison during turns and on irregular terrain. An analysis of the motor coordination problem on irregular terrain, where each motor must supply a different torque at a different speed is presented. A procedure was developed to match the output of each motor to the varying load. A design for the control system is given. The controller uses a microprocessor which interprets speed and steering commands from an off-board computer, and produces the appropriate drive voltages for the motors.
    Keywords: MECHANICAL ENGINEERING
    Type: NASA-CR-163501 , RPI-TR-MP-77
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  • 64
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    An advanced terrain modeler for an autonomous planetary rover (1980)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: A roving vehicle capable of autonomously exploring the surface of an alien world is under development and an advanced terrain modeler to characterize the possible paths of the rover as hazardous or safe is presented. This advanced terrain modeler has several improvements over the Troiani modeler that include: a crosspath analysis, better determination of hazards on slopes, and methods for dealing with missing returns at the extremities of the sensor field. The results from a package of programs to simulate the roving vehicle are then examined and compared to results from the Troiani modeler.
    Keywords: MECHANICAL ENGINEERING
    Type: NASA-CR-163485 , RPI-TR-MP-67
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  • 65
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    Feasibility of active feedback control of rotordynamic instability (1980)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: Some of the considerations involved in the use of feedback control as a means of eliminating or alleviating rotordynamic instability are discussed. A simple model of a mass on a flexible shaft is used to illustrate the application of feedback control concepts.
    Keywords: MECHANICAL ENGINEERING
    Type: NASA. Lewis Res. Center Rotordyn. Instability Probl. in High-Performance Turbomachinery; p 467-476
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  • 66
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    Lubrication of optimized-design tapered-roller bearings to 2.4 million DN (1980)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: The performance of 120.65 mm (4.75 in.) bore high speed design, tapered roller bearings was investigated at shaft speeds to 20,000 rpm (2.4 million DN) under combined thrust and radial load. The test bearing design was computer optimized for high speed operation. Temperature distribution bearing heat generation were determined as a function of shaft speed, radial and thrust loads, lubricant flow rates, and lubricant inlet temperature. The high speed design, tapered roller bearing operated successfully at shaft speeds up to 20,000 rpm under heavy thrust and radial loads. Bearing temperatures and heat generation with the high speed design bearing were significantly less than those of a modified standard bearing tested previously. Cup cooling was effective in decreasing the high cup temperatures to levels equal to the cone temperature.
    Keywords: MECHANICAL ENGINEERING
    Type: NASA-TP-1714 , E-270
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  • 67
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    Stabilization of aerodynamically excited turbomachinery with hydrodynamic journal bearings and supports (1980)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: A method of analyzing the first mode stability and unbalance response of multimass flexible rotors is presented whereby the multimass system is modeled as an equivalent single mass modal model including the effects of rotor flexibility, general linearized hydrodynamic journal bearings, squeeze film bearing supports and rotor aerodynamic cross coupling. Expressions for optimum bearing and support damping are presented for both stability and unbalance response. The method is intended to be used as a preliminary design tool to quickly ascertain the effects of bearing and support changes on rotor-bearing system performance.
    Keywords: MECHANICAL ENGINEERING
    Type: NASA. Lewis Res. Center Rotordyn. Instability Probl. in High-Performance Turbomachinery; p 429-452
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  • 68
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    Surface temperatures and glassy state investigations in tribology (1980)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: Measurements were made of the limiting shear stress for two naphthenic oils of differing molecular weight and three blends of the lower molecular weight oil and polymers of differing molecular weight. All reached the same limiting shear stress for the same temperature and pressure; although the polymer solutions reduced the limiting shear stress by about fifteen percent. A falling body viscometer was constructed to operate to 230 C and to 0.6 GPa and another was constructed to extend the pressure range to 1.1 GPa. A concentrated contact simulator was developed which allows recording of the traction force while the slide-roll ratio is continuously varied and the rolling speed is maintained essentially constant. Measurement of lubricant minimum film thickness of elliptical EHD contacts of various aspect ratios were made by optical interferometry. The experimental data were thirty percent greater than that predicted by the Hamrock and Dowson model. Preliminary development of the application of a scanning infrared radiation system to a tribological system was completed.
    Keywords: MECHANICAL ENGINEERING
    Type: NASA-CR-163389
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  • 69
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    Circumferential shaft seal (1980)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: A circumferential shaft seal is described which comprises two sealing rings held to a rotating shaft by means of a surrounding elastomeric band. 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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  • 70
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    Release mechanism for releasing and reattaching experiments on the Space Shuttle (1980)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: The release mechanism (REM) unlatches an experiment so that it can be moved about inside and outside the shuttle bay by the remote manipulator system (RMS), and then reattaches it to the REM base. Operated from the crew compartment after the RMS has been attached to the experiment, the REM releases the experiment by an electric motor driving a gear train and linkage which extracts four pins from holes in four plates. Electrical connectors on the REM are disengaged by the mechanical action of the structural pins retracting from the plates. When the REM releases the experiment, an unlatched indicator is actuated in the crew compartment, and then the experiment can be moved by using the RMS. To reattach the experiment to the REM, the RMS places the experiment with REM attachment angles against the flat, smooth surface of the REM; then the RMS moves the experiment into position for latchup. Actuation of an electric motor drives the four pins into the four holes in the plates. When fully latched, a switch actuated by the motion of the linkage, shuts the electric motor off and gives an indication to the crew compartment that the REM is latched.
    Keywords: MECHANICAL ENGINEERING
    Type: NASA-TP-1702 , M-301
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  • 71
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    Dynamic analysis of noncontacting face seals (1980)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: The dynamic behavior of a noncontacting coned face seal is analyzed taking into account various design parameters and operating conditions. The primary seal ring motion is expressed by a set of nonlinear equations for three degrees of freedom. These equations, which are solved numerically, allow identification of two dimensionless groups of parameters that affect the seal dynamic behavior. Stability maps for various seals are presented. These maps contain a stable-to-unstable transition region in which the ring wobbles at half the shaft frequency. The effect of various parameters on seal stability is discussed and an empirical expression for critical stability is offered.
    Keywords: MECHANICAL ENGINEERING
    Type: NASA-TM-79294 , E-458
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  • 72
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    Spur-Gear-System Efficiency at Part and Full Load (1980)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: A simple method for predicting the part- and full-load power loss of a steel spur gearset of arbitrary geometry supported by ball bearings is described. The analysis algebraically accounts for losses due to gear sliding, rolling traction, and windage in addition to support-ball-bearing losses. The analysis compares favorably with test data. A theoretical comparison of the component losses indicates that losses due to gear rolling traction, windage, and support bearings are significant and should be included along with gear sliding loss in a calculation of gear-system power loss.
    Keywords: MECHANICAL ENGINEERING
    Type: NASA-TP-1622 , AVRADCOM-TR-79-46 , E-061
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  • 73
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    Thermal elastohydrodynamic lubrication of spur gears (1980)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: An analysis and computer program called TELSGE were developed to predict the variations of dynamic load, surface temperature, and lubricant film thickness along the contacting path during the engagement of a pair of involute spur gears. The analysis of dynamic load includes the effect of gear inertia, the effect of load sharing of adjacent teeth, and the effect of variable tooth stiffness which are obtained by a finite-element method. Results obtained from TELSGE for the dynamic load distributions along the contacting path for various speeds of a pair of test gears show patterns similar to that observed experimentally. Effects of damping ratio, contact ratio, tip relief, and tooth error on the dynamic load were examined. In addition, two dimensionless charts are included for predicting the maximum equilibrium surface temperature, which can be used to estimate directly the lubricant film thickness based on well established EHD analysis.
    Keywords: MECHANICAL ENGINEERING
    Type: NASA-CR-3241
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  • 74
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    Self-acting lift-pad geometry for circumferential seals: A noncontacting concept (1980)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: A segmented circumferential seal with lift pads for hydrodynamic action was analyzed over ranges of speed and sealed pressure. Performance predictions, which predicted noncontact operation for speeds as high as 600 revolutions per second at sealed pressures to 86 N/sq cm, are discussed. Performance tests were performed on the seals and compared with the performance predictions.
    Keywords: MECHANICAL ENGINEERING
    Type: NASA-TP-1583 , E-154
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  • 75
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    Floating nut retention system (1980)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: A floating nut retention system includes a nut with a central aperture. An inner retainer plate has an opening which is fixedly aligned with the nut aperture. An outer retainer member is formed of a base plate having an opening and a surface adjacent to a surface of the inner retainer plate. The outer retainer member includes a securing mechanism for retaining the inner retainer plate adjacent to the outer retainer member. The securing mechanism enables the inner retainer plate to float with respect to the outer retainer number, while simultaneously forming a bearing surface for inner retainer plate.
    Keywords: MECHANICAL ENGINEERING
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  • 76
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    Drawer drive for space shuttle vacuum canister (1980)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: A sliding drawer type canister was designed to contain long duration exposure facility experiments which require vacuum storage before and after space exposure. The elastomeric seals require high closing loads which are generated through camming levers and transmitted through a spring loaded pressure plate. Lubrication was provided by various dry surface coatings. Higher than expected friction required some redesign after which the assembly functioned well and provided good sealing.
    Keywords: MECHANICAL ENGINEERING
    Type: NASA. Langley Res. Center Proc. of the 14th Aerospace Mech. Symp.; p 279-288
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  • 77
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    Fluid circulating pump operated by same incident solar energy which heats energy collection fluid (1980)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: The application of using a spacecraft solar powered pump terrestrially to reduce or eliminate the need for fossil fuel generated electricity for domestic solar hot water systems was investigated. A breadboard prototype model was constructed utilizing bimetals to convert thermal energy into mechanical motion by means of a toggle operated shutter mechanism. Although it did not meet expected thermal efficiency, the prototype model was sufficient to demonstrate the mechanical concept.
    Keywords: MECHANICAL ENGINEERING
    Type: NASA. Langley Res. Center Proc. of the 14th Aerospace Mech. Symp.; p 47-56
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  • 78
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    Design study of flat belt CVT for electric vehicles (1980)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: A continuously variable transmission (CVT) was studied, using a novel flat belt pulley arrangement which couples the high speed output shaft of an energy storage flywheel to the drive train of an electric vehicle. A specific CVT arrangement was recommended and its components were selected and sized, based on the design requirements of a 1700 KG vehicle. A design layout was prepared and engineering calculations made of component efficiencies and operating life. The transmission efficiency was calculated to be significantly over 90% with the expected vehicle operation. A design consistent with automotive practice for low future production costs was considered, together with maintainability. The technology advancements required to develop the flat belt CVT were identified and an estimate was made of how the size of the flat belt CVT scales to larger and smaller design output torques. The suitability of the flat belt CVT for alternate application to an electric vehicle powered by an electric motor without flywheel and to a hybrid electric vehicle powered by an electric motor with an internal combustion engine was studied.
    Keywords: MECHANICAL ENGINEERING
    Type: NASA-CR-159822 , P-1006
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  • 79
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    Dynamic response to rotating-seat runout in non-contacting face seals (1980)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: The dynamic response of a flexibly mounted ring to runout of the rotating seat in mechanical face seals is analyzed assuming small perturbations. It is found that tracking ability of the stator depends only on its dynamic characteristics and operating conditions and is not affected by the amount of runout. Three different modes of dynamic response are shown and the condition for parallel tracking is presented.
    Keywords: MECHANICAL ENGINEERING
    Type: NASA-TM-81490 , E-392
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  • 80
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    On the characteristics of centrifugal-reciprocating machines (1980)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: A method of compressing helium gas for cryogenic coolers is presented which uses centrifugal force to reduce the forces on the connecting rod and crankshaft in the usual reciprocating compressor. This is achieved by rotating the piston-cylinder assembly at a speed sufficient for the centrifugal force on the piston to overcome the compressional force due to the working fluid. The rotating assembly is dynamically braked in order to recharge the working space with fluid. The intake stroke consists of decelerating the rotating piston-cylinder assembly and the exhaust stroke consists of accelerating the assembly.
    Keywords: MECHANICAL ENGINEERING
    Type: NASA-CR-162881 , JPL-PUB-79-108
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  • 81
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    Ferrographic and spectrographic analysis of oil sampled before and after failure of a jet engine (1980)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: An experimental gas turbine engine was destroyed as a result of the combustion of its titanium components. Several engine oil samples (before and after the failure) were analyzed with a Ferrograph as well as plasma, atomic absorption, and emission spectrometers. The analyses indicated that a lubrication system failure was not a causative factor in the engine failure. Neither an abnormal wear mechanism, nor a high level of wear debris was detected in the oil sample from the engine just prior to the test in which the failure occurred. However, low concentrations of titanium were evident in this sample and samples taken earlier. After the failure, higher titanium concentrations were detected in oil samples taken from different engine locations. Ferrographic analysis indicated that most of the titanium was contained in spherical metallic debris after the failure.
    Keywords: MECHANICAL ENGINEERING
    Type: NASA-TM-81430 , E-353
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  • 82
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    Damping in tapered annular seals for an incompressible fluid (1980)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: Damping in annular seals is calculated for an incompressible fluid. Results show that damping in tapered seals optimized for stiffness is considerably less than that in straight seals for the same minimum clearance. Damping in rotating seals can promote fractional frequency whirl. Neglecting fluid acceleration makes solution much easier, but leads to errors in calculated damping of up to 16 percent.
    Keywords: MECHANICAL ENGINEERING
    Type: NASA-TP-1646 , E-124
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  • 83
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    Analysis and design of a uniform-clearance, pumping-ring rod seal for the Stirling engine (1980)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: A uniform clearance pumping ring, as opposed to the conventional taper clearance one, is described. The uniform clearance concept eliminates complex elastohydrodynamic problems and enables a simple analytical treatment to be made. An analytical expression is derived for the pumping rate showing the effect of various design parameters on the pumping ring's performance. An optimum clearance is found by which the pumping rate is maximized and a numerical example is presented to demonstrate the potential of the uniform clearance design.
    Keywords: MECHANICAL ENGINEERING
    Type: NASA-TM-81463 , E-080
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  • 84
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    Cryogenic container compound suspension strap (1980)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: A support strap for use in a cryogenic storage vessel for supporting the inner shell from the outer shell with a minimum heat leak is presented. The compound suspension strap is made from a unidirectional fiberglass epoxy composite material with an ultimate tensile strength and fatigue strength which are approximately doubled when the material is cooled to a cryogenic temperature.
    Keywords: MECHANICAL ENGINEERING
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  • 85
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    A linear photodiode array employed in a short range laser triangulation obstacle avoidance sensor (1980)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: An opto-electronic receiver incorporating a multi-element linear photodiode array as a component of a laser-triangulation rangefinder was developed as an obstacle avoidance sensor for a Martian roving vehicle. The detector can resolve the angle of laser return in 1.5 deg increments within a field of view of 30 deg and a range of five meters. A second receiver with a 1024 elements over 60 deg and a 3 meter range is also documented. Design criteria, circuit operation, schematics, experimental results and calibration procedures are discussed.
    Keywords: MECHANICAL ENGINEERING
    Type: NASA-CR-163613 , RPI-TR-MP-74
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  • 86
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    Belt for transmitting power from a cogged driving member to a cogged driven member (1980)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: A belt for transmitting power from a cogged driving member to a cogged driven member such as a pair of wheel sprockets is described. The belt has inflexible teeth spaced along the direction of its travel. Each of the teeth has a longitudinal axis transverse to the direction of belt travel. The belt also includes substantially inextensible fasts spaced transversely to the direction of belt travel. The fasts extend in the direction of belt travel adjacent to the teeth and are looped around preselected numbers of the teeth.
    Keywords: MECHANICAL ENGINEERING
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  • 87
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    Redundant motor drive system (1980)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: A drive system characterized by a base supporting a pair of pillars arranged in spaced parallelism, a shaft extended between and supported by the pillars for rotation about the longitudinal axis thereof, a worm gear affixed to the shaft and supported in coaxial relation therewith is described. A bearing housing of a sleeve like configuration is concentrically related to the shaft and is supported thereby for free rotation. A first and a second quiescent drive train, alternatively activatable, is provided for imparting rotation into said bearing housing. Each of the drive trains is characterized by a selectively energizable motor connected to a spur gear.
    Keywords: MECHANICAL ENGINEERING
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  • 88
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    Instability thresholds for flexible rotors in hydrodynamic bearings (1980)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: Two types of fixed pad hydrodynamic bearings (multilobe and pressure dam) were considered. Optimum and nonoptimum geometric configurations were tested. The optimum geometric configurations were determined by using a theoretical analysis and then the bearings were constructed for a flexible rotor test rig. It was found that optimizing bearings using this technique produces a 100% or greater increase in rotor stability. It is shown that this increase in rotor stability is carried out in the absence of certain types of instability mechanisms such as aerodynamic crosscoupling. However, the increase in rotor stability should greatly improve rotating machinery performance in the presence of such forces as well.
    Keywords: MECHANICAL ENGINEERING
    Type: NASA. Lewis Res. Center Rotordyn. Instability Probl. in High-Performance Turbomachinery; p 403-427
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  • 89
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    A test program to measure fluid mechanical whirl-excitation forces in centrifugal pumps (1980)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: The details of a test program for the measurement of the unsteady forces on centrifugal impellers are discussed. Various hydrodynamic flows are identified as possible contributors to these destabilizing forces.
    Keywords: MECHANICAL ENGINEERING
    Type: NASA. Lewis Res. Center Rotordyn. Instability Probl. in High-Performance Turbomachinery; p 229-247
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  • 90
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    Testing of turbulent seals for rotodynamic coefficients (1980)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: A test program developed for dynamic testing of straight and convergent-tapered seals, with the capability of separately determining both direct and cross-coupled stiffness, damping, and added mass coefficients is described. The test apparatus causes the seal journal to execute small-eccentricity centered circular orbits within its bearings. Dynamic measurements are made and recorded of the seal-displacement-vector components, and of the pressure field. The pressure field is integrated to yield seal reaction force components. The displacement and force vector components are analyzed via a generalized Newton-Raphson procedure to yield the desired seal dynamic coefficients. Representative test data are provided and discussed.
    Keywords: MECHANICAL ENGINEERING
    Type: NASA. Lewis Res. Center Rotordyn. Instability Probl. in High-Performance Turbomachinery; p 121-138
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  • 91
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    System for slicing silicon wafers (1980)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: An improved system is described which has at least one endless band saw blade that is characterized by a continuously regenerated cutting edge and is unidirectionally driven along a pair of courses extended in mutual parallelism through a cutting station located near the midportion of the courses. The blade is supported at the cutting station by pairs of guides continuously rotated through less than 360 deg of angular displacement during each cutting operation in order to continuously regenerate the blade supporting surfaces of the guide. Blade wobble is thus substantially eliminated.
    Keywords: MECHANICAL ENGINEERING
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  • 92
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    Superconducting bearings for application in cryogenic experiments in space (1980)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: Linear superconducting magnetic bearings suitable for use in a proposed orbital equivalence principle experiment and for general application in space were developed and tested. Current flows in opposite directions in adjacent superconducting wires arranged parallel to the axis of a cylinder. This configuration provides maximum stiffness radially while allowing the test mass to move freely along the cylinder axis. In a space application, the wires are extended to cover the entire perimeter of the cylinder: for the earth-based tests it was desirable to use only the bottom half. Control of the axial position of the test mass is by small control coils which may be positioned inside or outside the main bearing. The design is suitable for application to other geometries where maximum stiffness is desired. A working model scaled to operate in a 1-g environment was perfected approximate solutions for the bearings were developed. A superconducting transformer method of charging the magnets for the bearing, and a position detector based on a SQUID magnetometer and associated superconducting circuit were also investigated.
    Keywords: MECHANICAL ENGINEERING
    Type: NASA-CR-161526
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  • 93
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    Unknown
    Cables and connectors for Large Space System Technology (LSST) (1980)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: The effect of the environment and extravehicular activity/remote assembly operations on the cables and connectors for spacecraft with metallic and/or nonmetallic structures was examined. Cable and connector philosophy was outlined for the electrical systems and electronic compartments which contain high-voltage, high-power electrical and electronic equipment. The influence of plasma and particulates on the system is analyzed and the effect of static buildup on the spacecraft electrical system discussed. Conceptual cable and connector designs are assessed for capability to withstand high current and high voltage without danger of arcs and electromagnetic interference. The extravehicular activites required of the space station and/or supply spacecraft crew members to join and inspect the electrical system, using manual or remote assembly construction are also considered.
    Keywords: MECHANICAL ENGINEERING
    Type: NASA-CR-161423
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 94
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    Unknown
    Composite seal for turbomachinery (1980)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    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 compliant material covered with a thin ductile layer. A mounting fixture surrounds the backing.
    Keywords: MECHANICAL ENGINEERING
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 95
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    Unknown
    Design study of toroidal traction CVT for electric vehicles (1980)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: The development, evaluation, and optimization of a preliminary design concept for a continuously variable transmission (CVT) to couple the high-speed output shaft of an energy storage flywheel to the drive train of an electric vehicle is discussed. An existing computer simulation program was modified and used to compare the performance of five CVT design configurations. Based on this analysis, a dual-cavity full-toroidal drive with regenerative gearing is selected for the CVT design configuration. Three areas are identified that will require some technological development: the ratio control system, the traction fluid properities, and evaluation of the traction contact performance. Finally, the suitability of the selected CVT design concept for alternate electric and hybrid vehicle applications and alternate vehicle sizes and maximum output torques is determined. In all cases the toroidal traction drive design concept is applicable to the vehicle system. The regenerative gearing could be eliminated in the electric powered vehicle because of the reduced ratio range requirements. In other cases the CVT with regenerative gearing would meet the design requirements after appropriate adjustments in size and reduction gearing ratio.
    Keywords: MECHANICAL ENGINEERING
    Type: NASA-CR-159803 , DOE/NASA/0117-80/1 , REPT-80-16762
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 96
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    Unknown
    Study of rolling element dynamic interactions with separator and raceway paths. Roller skewing measurements in roller bearings (1980)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: Measurements of roller skewing in a 118 mm bore roller bearing operating at shaft speeds to 12000 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 .4 to .5 degrees were observed with .5 degree misalignment.
    Keywords: MECHANICAL ENGINEERING
    Type: NASA-CR-163186
    Format: application/pdf
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  • 97
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    Method and apparatus for holding two separate metal pieces together for welding (1980)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: A method of holding two separate metal pieces together for welding is described including the steps of overlapping a portion of one of the metal pieces on a portion of the other metal piece, encasing the overlapping metal piece in a compressible device, drawing the compressible device into an enclosure, and compressing a portion of the compressible device around the overlapping portions of the metal pieces for holding the metal pieces under constant and equal pressure during welding. The preferred apparatus for performing the method utilizes a support mechanism to support the two separate metal pieces in an overlapping configuration; a compressible device surrounding the support mechanism and at least one of the metal pieces, and a compressing device surrounding the compressible device for compressing the compressible device around the overlapping portions of the metal pieces, thus providing constant and equal pressure at all points on the overlapping portions of the metal pieces.
    Keywords: MECHANICAL ENGINEERING
    Format: application/pdf
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  • 98
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    Unknown
    Comparison of predicted and experimental performance of large-bore roller bearing operating to 3.0 million DN (1980)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: Bearing inner and outer race temperatures and the amount of heat transferred to the lubricant were calculated by using the computer program CYBEAN. The results obtained were compared with previously reported experimental data for a 118 mm bore roller bearing that operated at shaft speeds to 25,500 rpm, radial loads to 8,900 N (2000 lb), and total lubricant flow rates to 0.0102 cu m/min (2.7 gal/min). The calculated results compared well with the experimental data.
    Keywords: MECHANICAL ENGINEERING
    Type: NASA-TP-1599 , E-063
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 99
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    Modified spiral wound retaining ring (1980)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: A spiral wound retaining ring with angled ends is described. The ring is crimped at the same angle as the ring ends to maintain a constant thickness dimension. The angling of the ends of the ring and crimp allow the ends to be positioned closer together while maintaining enough clearance to enable insertion and removal of the ring. By reducing the separation distance between the ends a stronger ring results since the double layer area of the ring is maximized.
    Keywords: MECHANICAL ENGINEERING
    Format: application/pdf
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  • 100
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    Unknown
    Heat generation in aircraft tires under free rolling conditions (1980)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Effort is directed toward construction of a rational method for evaluating internal temperatures of aircraft tires. Enhanced predictability of tire temperature buildup is a design tool in both the tire and airframe industries.
    Keywords: MECHANICAL ENGINEERING
    Type: NASA-CR-164273
    Format: application/pdf
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