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  • 1
    Publication Date: 2019-07-13
    Description: No abstract available
    Keywords: Mechanical Engineering
    Type: Mechanical Systems Engineering Spacecraft Structures and Dynamics; Jun 19, 2012 - Jun 21, 2012; El Segundo, CA; United States
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  • 2
    Publication Date: 2019-07-13
    Description: No abstract available
    Keywords: Launch Vehicles and Launch Operations
    Type: Spacecraft and Launch Vehicle Dynamics Environments; Jun 19, 2012 - Jun 21, 2012; El Segundo, CA; United States
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  • 3
    Publication Date: 2019-07-13
    Description: The Terrestrial Planet Finder mission requires extreme dynamic stability at cryogenic temperatures in order to carry out its objectives of searching for and observing extraterrestrial planets.
    Keywords: Engineering (General)
    Type: International Society for Optical Engineering (SPIE) Optics and Photonics 2005 Symposium; Jul 31, 2005 - Aug 04, 2005; San Diego, CA; United States
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  • 4
    Publication Date: 2019-07-13
    Description: This paper describes a unique experimental facility designed to measure damping of materials at cryogenic temperatures for the Terrestrial Planet Finder (TPF) mission at the Jet Propulsion Laboratory. The test facility removes other sources of damping in the measurement by avoiding frictional interfaces, decoupling the test specimen from the support system, and by using a non-contacting measurement device. Damping data reported herein are obtained for materials (Aluminum, Aluminum/Terbium/Dysprosium, Titanium, Composites) vibrating in free-free bending modes with low strain levels (〈 10(exp -6) ppm). The fundamental frequencies of material samples are ranged from 14 to 202 Hz. To provide the most beneficial data relevant to TPF-like precision optical space missions, the damping data are collected from room temperatures (around 293 K) to cryogenic temperatures (below 40 K) at unevenly-spaced intervals. More data points are collected over any region of interest. The test data shows a significant decrease in viscous damping at cryogenic temperatures. The cryogenic damping can be as low as 10(exp -4) %, but the amount of the damping decrease is a function of frequency and material. However, Titanium 15-3-3-3 shows a remarkable increase in damping at cryogenic temperatures. It demonstrates over one order of magnitude increase in damping in comparison to Aluminum 6061-T6. Given its other properties (e.g., good stiffness and low conductivity) this may prove itself to be a good candidate for the application on TPF. At room temperatures, the test data are correlated well with the damping predicted by the Zener theory. However, large discrepancies at cryogenic temperatures between the Zener theory and the test data are observed.
    Keywords: Chemistry and Materials (General)
    Type: SPIE 49th International Symposium on Optical Science and Technology; Aug 02, 2004 - Aug 06, 2004; Denver, CO; United States
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  • 5
    Publication Date: 2019-07-13
    Description: Touchdown Driving Requirement: The mechanical system surface element shall be capable of facilitating a safe, stable landing at terrain angles up to 15 degrees, given an initial vertical velocity of 1 m/sec, horizontal velocity of 0.5 m/sec, and Z-axis spin rate of [4] deg/sec.Touchdown Loads Development: A multi-year development effort has been successfully conducted leading to an innovative analytical methodology for the prediction of rover touchdown design loads and the assessment of rover touchdown stability.
    Keywords: Spacecraft Design, Testing and Performance
    Type: Spacecraft and Lauch Vehicle Dynamic Environments Workshop; Jun 27, 2006 - Jun 29, 2006; Hawthorne, CA; United States
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  • 6
    Publication Date: 2019-07-13
    Description: This paper summarizes a dynamic analysis conducted in support of the investigation of the anomalous deployment of the Galileo High Gain Antenna on April 11, 1991. The work was focused on modeling the spacecraft spin dynamics to predict and compare the spin detector telemetry during the antenna deployment for possible cause scenarios. The effects of analog and digital low-pass filtering, digitization, and telemetry on the reported spin rate were studied as well. The high frequency phenomena in the spin detector response are masked by the filtering and sampling of the telemetry data. However, the observed spin detector telemetery is consistent with a single rib popping free, and is most likely associated with a rib near the spin detector, or 180 deg opposite.
    Keywords: SPACECRAFT DESIGN, TESTING AND PERFORMANCE
    Type: AIAA PAPER 92-2455 , AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics and Materials Conference; Apr 13, 1992 - Apr 15, 1992; Dallas, TX; United States
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  • 7
    Publication Date: 2019-07-13
    Description: No abstract available
    Keywords: Spacecraft Design, Testing and Performance
    Type: Spacecraft and Launch Vehicle Dynamic Environments Workshop; Jun 08, 2010 - Jun 10, 2010; El Segundo, CA; United States
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  • 8
    Publication Date: 2019-07-13
    Description: Mars Science Laboratory (MSL) will use the Skycrane architecture to execute final descent and landing maneuvers. The Skycrane phase uses closed-loop feedback control throughout the entire phase, starting with rover separation, through mobility deploy, and through touchdown, ending only when the bridles have completely slacked. The integrated ADAMS simulation described in this paper couples complex dynamical models created by the mechanical subsystem with actual GNC flight software algorithms that have been compiled and linked into ADAMS. These integrated simulations provide the project with the best means to verify key Skycrane requirements which have a tightly coupled GNC-Mechanical aspect to them. It also provides the best opportunity to validate the design of the algorithm that determines when to cut the bridles. The results of the simulations show the excellent performance of the Skycrane system.
    Keywords: Mechanical Engineering
    Type: IEEE Aerospace Conference; Mar 03, 2012 - Mar 10, 2012; Big Sky, MT; United States
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  • 9
    Publication Date: 2019-07-13
    Description: A wheel experiencing sinkage and slippage events poses a high risk to rover missions as evidenced by recent mobility challenges on the Mars Exploration Rover (MER) project. Because several factors contribute to wheel sinkage and slippage conditions such as soil composition, large deformation soil behavior, wheel geometry, nonlinear contact forces, terrain irregularity, etc., there are significant benefits to modeling these events to a sufficient degree of complexity. For the purposes of modeling wheel sinkage and slippage at an engineering scale, meshfree finite element approaches enable simulations that capture sufficient detail of wheel-soil interaction while remaining computationally feasible. This study demonstrates some of the large deformation modeling capability of meshfree methods and the realistic solutions obtained by accounting for the soil material properties. A benchmark wheel-soil interaction problem is developed and analyzed using a specific class of meshfree methods called Reproducing Kernel Particle Method (RKPM). The benchmark problem is also analyzed using a commercially available finite element approach with Lagrangian meshing for comparison. RKPM results are comparable to classical pressure-sinkage terramechanics relationships proposed by Bekker-Wong. Pending experimental calibration by future work, the meshfree modeling technique will be a viable simulation tool for trade studies assisting rover wheel design.
    Keywords: Spacecraft Design, Testing and Performance; Numerical Analysis
    Type: AIAA Guidance, Navigation, and Control Conference and Co-located Conference; Aug 13, 2012 - Aug 16, 2012; Minneapolis, MN; United States
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  • 10
    Publication Date: 2019-07-13
    Description: No abstract available
    Keywords: Space Communications, Spacecraft Communications, Command and Tracking; Launch Vehicles and Launch Operations
    Type: MSC Software 2013 Users Conference; May 07, 2013 - May 08, 2013; Irvine, CA; United States
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