Scientific and Technical Aerospace Reports Volume 38 July 28, 2000

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20000067635 NASA Marshall Space Flight Center, Huntsville, AL USA A Survey of Active Vibration Isolation Systems for Microgravity Applications Grodsinsky, Carlos M., Bicron Corp., USA; Whorton, Mark S., NASA Marshall Space Flight Center, USA; [2000]; 45p; In English Contract(s)/Grant(s): RTOP 398-96-02; No Copyright; Avail: CASI; A03, Hardcopy; A01, Microfiche In view of the utility of space vehicles as orbiting science laboratories, the need for vibration isolation systems for acceleration sensitive experiments has gained increasing visibility. to date, three active microgravity vibration isolation systems have successfully been demonstrated in flight. This paper provides a tutorial discussion of the microgravity vibration isolation problem including a description of the acceleration environment of the International Space Station and attenuation requirements as well as a comparison of the dynamics of passive isolation, active rack-level isolation, and active payload-level isolation. This paper also surveys the flight test results of the three demonstrated systems: Suppression of Transient Accelerations by Levitation (STABLE); the Microgravity Vibration Isolation Mount (MIM); and the Active Rack Isolation System (ARIS). Author Isolation; Systems Engineering; Vibration Isolators; Microgravity 20000067649 Boeing Co., Rocketdyne Propulsion and Power, Canoga Park, CA USA Laser Brazing of High Temperature Braze Alloy Gao, Y. P., Boeing Co., USA; Seaman, R. F., Boeing Co., USA; McQuillan, T. J., Boeing Co., USA; Martiens, R. F., Boeing Co., USA; [2000]; 2p; In English, Apr. 2000, Chicago, IL, USA; Sponsored by American Welding Society, USA Contract(s)/Grant(s): NAS8-45000; No Copyright; Avail: Issuing Activity; Abstract Only The Space Shuttle Main Engine (SSME) consists of 1080 conical tubes, which are furnace brazed themselves, manifolds, and surrounding structural jacket making almost four miles of braze joints. Subsequent furnace braze cycles are performed due to localized braze voids between the coolant tubes. SSME nozzle experiences extremely high heat flux (180 mW/sq m) during hot fire. Braze voids between coolant tubes may result in hot combustion gas escape causing jacket bulges. The nozzle can be disqualified for flight or result in mission failure if the braze voids exceed the limits. Localized braze processes were considered to eliminate braze voids, however, damage to the parent materials often prohibited use of such process. Being the only manned flight reusable rocket engine, it has stringent requirement on the braze process. Poor braze quality or damage to the parent materials limits the nozzle service life. The objective of this study was to develop a laser brazing process to provide quality, localized braze joints without adverse affect on the parent materials. Gold (Au-Cu-Ni-Pd-Mn) based high temperature braze alloys were used in both powder and wire form. Thin section iron base superalloy A286 tube was used as substrate materials. Different Laser Systems including CO2 (10.6 micrometers, 1kW), ND:YAG (1.06 micrometers, 4kW). and direct diode laser (808nm. 150W) were investigated for brazing process. The laser process variables including wavelength. laser power, travel speed and angle of inclination were optimized according to bead geometry and braze alloy wetting at minimum heat input level, The properties of laser brazing were compared to that of furnace brazing. Microhardness profiles were used for braze joint property comparison between laser and furnace brazing. The cooling rate of laser brazing was compared to furnace brazing based on secondary dendritic arm spacing, Both optical and Scanning Electron Microscope (SEM) were used to evaluate the microstructures of the braze materials and tube substrate. Metallography of the laser braze joint was compared to the furnace braze. SEM Energy Disperse X-Ray Spectra (EDX) and back scattered imaging were used to analyze braze alloy segregation. Although all of the laser systems, CO2, ND:YAG, and direct diode laser produced good braze joint, the direct diode laser was selected for its system simplicity, compactness and portability. Excellent laser and braze alloy coupling is observed with powder alloy compared to braze alloy wire. Good wetting is found with different gold based braze alloys. The laser brazing process can be optimized so that the adverse affect on the parent materials can be eliminated. Metallography of the laser braze joint has shown that quality braze joint was produced with laser brazing process. Penetration of the laser braze to the substrate is at neglectable level. Zero penetration is observed. Microstructure examinations shown that no observable changes of the microstructure (grain structure and precipitation) in the HAZ area between laser braze and furnace braze. Wide gaps can be laser brazed with single pass for up to 0.024 inches. Finer dendritic structure is observed in laser brazing compared with equiaxial and coarser grain of the furnace brazing microstructure. Greater segregation is also found in the furnace braze. Higher hardness of the laser braze joint comparing to furnace braze is observed due to the fast cooling rate and Finer microstructure in the laser brazing. Laser braze joint properties meet or exceed the furnace joint properties. Direct diode laser for thin section tube brazing with high temperature braze alloys have been successfully demonstrated. The laser’s high energy density and precise control has shown significant advantages in reducing process heat input to the substrates and provide high quality braze joints comparing to other localized braze process such as torch, TIG, and MPTA processes. Significant cost savings can be realized particularly with localized braze comparing to a full furnace braze cycle. Author Brazing; Heat Resistant Alloys; High Temperature; Furnaces; Semiconductor Lasers 94
20000067659 NASA Marshall Space Flight Center, Huntsville, AL USA Pin Load Control Applied to Retractable Pin Tool Technology and its Characterization Oelgoetz, Peter, Boeing Co., USA; [2000]; 17p; In English; AeroMat 2000, 28 Jun. 2000, Bellevue, WA, USA Contract(s)/Grant(s): NASA Order H-31946-D; No Copyright; Avail: CASI; A03, Hardcopy; A01, Microfiche Until the development of retractable pin tool (RPT) technology, friction stir welding (FSW) was limited to constant thickness joining of aluminum materials and the choices of keyhole elimination focused on traditional fusion and plug weld repair techniques. An invention, US Patent Number 5,893.507, ”Auto-Adjustable Pin Tool for Friction Stir Welding” assigned to NASA, demonstrated an approach to resolve these serious drawbacks. This approach brings forth a technique that allows the crater, or keyhole, to be closed out automatically at the end of the weld joint without adding any additional equipment or material. Also the probe length can be varied automatically in the weld joint to compensate for material thickness changes, such as, in a tapered joint. This paper reports the effects of pin extension and retraction rates in the weld joint and its correlation to weld quality. The investigation utilized a pin load-detecting device that was integrated in the Phase 2A RPT designed by Boeing for NASA/MSFC. The RPT modification provided pin load data that was accessed and used to eliminate root side indications and determine pin manipulation rates necessary to produce consistence homogeneous joints. Author Friction Welding; Welded Joints; Retractable Equipment; Pins 38 QUALITY ASSURANCE AND RELIABILITY �� 20000065660 Jet Propulsion Lab., California Inst. of Tech., Pasadena, CA USA NDE and Advanced Actuators for Space Applications at JPL Bar-Cohen, Yoseph, Jet Propulsion Lab., California Inst. of Tech., USA; [1999]; 20p; In English, Jun. 1999, Japan; No Copyright; Avail: CASI; A03, Hardcopy; A01, Microfiche Nondestructive Evaluation and Advanced Actuators (NDEAA) are presented. The focus areas are on mechanisms and devices that are driven by acoustic or elastic waves. The topics include: 1) Nondestructive Evaluation; 2) Advanced Actuators; 3) Ultrasonic Medical Diagnostics and Treatment; and 4) Telerobotics. CASI Actuators; Nondestructive Tests; Technology Utilization; Ultrasonics 39 STRUCTURAL MECHANICS �� 20000063501 Ohio Aerospace Inst., Cleveland, OH USA Cumulative Axial and Torsional Fatigue: An Investigation of Load-Type Sequencing Effects Kalluri, Sreeramesh, Ohio Aerospace Inst., USA; Bonacuse, Peter J., Army Research Lab., USA; [2000]; 48p; In English; Multiaxial Fatigue and Deformation: Testing and Prediction, 19-20 May 1999, Seattle, WA, USA; Sponsored by American Society for Testing and Materials, USA Contract(s)/Grant(s): RTOP 505-23-AM Report No.(s): Paper 8013; No Copyright; Avail: CASI; A03, Hardcopy; A01, Microfiche Cumulative fatigue behavior of a wrought cobalt-base superalloy, Haynes 188 was investigated at 538 C under various singlestep sequences of axial and torsional loading conditions. Initially, fully-reversed, axial and torsional fatigue tests were conducted under strain control at 538 C on thin-walled tubular specimens to establish baseline fatigue life relationships. Subsequently, four sequences (axial/axial, torsional/torsional, axial/torsional, and torsional/axial) of two load-level fatigue tests were conducted to characterize both the load-order (high/low) and load-type sequencing effects. For the two load-level tests, summations of life fractions and the remaining fatigue lives at the second load-level were computed by the Miner’s Linear Damage Rule (LDR) and a nonlinear Damage Curve Approach (DCA). In general, for all four cases predictions by LDR were unconservative. Predictions 95
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Scientific and Technical Aerospace
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Introduction Scientific and Technic
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Subject Divisions Table of Contents
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ground equipment and systems. For a
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Subject Categories of the Division
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48 Oceanography 139 Includes the ph
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72 Atomic and Molecular Physics 191
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Document Availability Information T
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Avail: NASA Public Document Rooms.
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NASA CASI Price Tables — Effectiv
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ALABAMA AUBURN UNIV. AT MONTGOMERY
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20000061433 Pisa Univ., Dipartiment
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English; 34th; 34th Thermophysics C
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ciency of the generated derivative
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20000063509 NASA Glenn Research Cen
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05 AIRCRAFT DESIGN, TESTING AND PER
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A long tradition of aerodynamic des
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sonic and transonic cases will be p
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20000061449 British Aerospace Publi
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20000064593 NASA Langley Research C
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performance required for a proposed
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ment cost and create better product
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tion (NPSS), is focused on the inte
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surface measurement techniques used
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with emphasis on the search for lin
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20000063520 NASA Kennedy Space Cent
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primary issues for it’s adaptatio
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Footage shows the night vertical ta
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necessary for ignition modeling, or
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engine lifetime, and high power ope
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Page 125 and 126: 20000064527 Analytical Imaging and
Page 127 and 128: 20000064533 Austin State Univ., Dep
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Page 133 and 134: in Yellowstone National Park. We ar
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Page 155 and 156: We investigate the compositional di
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Page 159 and 160: This report presents the Applied Me
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20000064015 Institute for Human Fac
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during 50% (SD 4%) of the breathing
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20000064711 Massachusetts Inst. of
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The analysis of this smaller data s
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vided a functional helmet mount. Th
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61 COMPUTER PROGRAMMING AND SOFTWAR
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The goal of multi-image classificat
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20000063526 Defence Science and Tec
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85 dB amplifier design evolved by o
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20000064594 New Mexico Univ., Elect
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20000064615 NASA Ames Research Cent
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declarations with a pattern recogni
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containing point where interpolatio
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has his own responsibility, while t
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the people, documents and projects
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and experimental technology, many o
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tems. In particular this applicatio
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Over the past decade, high performa
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expensive than a single analysis. I
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20000064726 Carnegie-Mellon Univ.,
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20000064099 Teledyne Brown Engineer
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20000066597 Geophysical Observatory
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20000065633 Institute TNO of Applie
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important conclusion is that for su
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est frame of the string. The modifi
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isotopes. The method and program we
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A detailed study is undertaken, usi
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20000063497 Kaiser Electro-Optics,
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delivers 60% of the x-ray flux from
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76 SOLID-STATE PHYSICS ��
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20000064660 Abdus Salam Internation
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20000067648 NASA Marshall Space Fli
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20000064703 Institute of Atomic Ene
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The BRST approach is applied to the
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20000067671 Hampton Univ., VA USA A
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82 DOCUMENTATION AND INFORMATION SC
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ecoming almost too cumbersome to be
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physical world. These are the two p
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with WFPC2 data. Tests of HSTphot
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A brief description is given of the
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20000064070 NASA Ames Research Cent
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gas, show variations that have rema
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egy, called Power In that would all
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20000064089 Smithsonian Astrophysic
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A ABERRATION, 143, 198 ABRASION, 22
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COMPRESSIBLE FLOW, 83 COMPRESSION L
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FATIGUE (MATERIALS), 50, 93, 96 FAT
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LASING, 90 LATE STARS, 224 LATITUDE
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PATCH ANTENNAS, 74 PATHOLOGY, 98 PA
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SPACE PLATFORMS, 38 SPACE PROBES, 2
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WIND PROFILES, 137 WIND TUNNEL TEST
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Brown, Andy, 38 Brown, April S., 20
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Grosvenor, C. A., 70 Grosvenor, J.
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Lu, Gui-Ying, 50 Lugg, Desmond J.,
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Robertson, Tony, 39 Robinson, Jeffr
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Warner, J. D., 63 Warren, James, 16
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Scientific and Technical Aerospace Reports Volume 38 July 28, 2000

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