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  • 1
    Publication Date: 2011-08-24
    Description: The next generation of large, flexible space structures will be too light to support their own weight, requiring a system of structural supports for ground testing. The authors have proposed multiple boundary-condition testing (MBCT), using more than one support condition to reduce uncertainties associated with the supports. MBCT would revise the mass and stiffness matrix, analytically qualifying the structure for operation in space. The same procedure is applicable to other common test conditions, such as empty/loaded tanks and subsystem/system level tests. This paper examines three techniques for constructing the covariance matrix required by nonlinear generalized least squares (NGLS) to update structural models based on modal test data. The methods range from a complicated approach used to generate the simulation data (i.e., the correct answer) to a diagonal matrix based on only two constants. The results show that NGLS is very insensitive to assumptions about the covariance matrix, suggesting that a workable NGLS procedure is possible. The examples also indicate that the multiple boundary condition procedure more accurately reduces errors than individual boundary condition tests alone.
    Keywords: SPACECRAFT DESIGN, TESTING AND PERFORMANCE
    Type: AIAA Journal (ISSN 0001-1452); 30; 226-233
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  • 2
    Publication Date: 2011-08-18
    Description: A fault model and a system model are necessary to assess the tolerance or resilience of a digital system to lightning-induced transients. It is noted that these models are usually developed separately. A new approach is outlined here for this assessment problem which combines the fault and system models into an overall model. With this approach, referred to as the containment set approach, an assessment of the effects of lightning-induced transients can be made in terms of a state transition matrix. This matrix can be generated by means of fault injection experiments. In addition, certain nonredundancy-oriented design alternatives to the achievement of lightning-induced transient tolerance in digital systems are indicated by the containment set approach.
    Keywords: ELECTRONICS AND ELECTRICAL ENGINEERING
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  • 3
    Publication Date: 2017-10-02
    Description: For the structural dynamic analysis of large space structures, the technology in structural synthesis and the development of structural analysis software have increased the capability to predict the dynamic characteristics of the structural system. The various subsystems which comprise the system are represented by various displacement functions; the displacement functions are then combined to represent the total structure. Experience has indicated that even when subsystem mathematical models are verified by test, the mathematical representations of the total system are often in error because the mathematical model of the structural elements which are significant when loads are applied at the interconnection points are not adequately verified by test. A multiple test concept, based upon the Multiple Boundary Condition Test (MBCT), is presented which will increase the accuracy of the system mathematical model by improving the subsystem test and test/analysis correlation procedure.
    Keywords: SPACECRAFT DESIGN, TESTING AND PERFORMANCE
    Type: Shock and Vibration Information Center The Shock and Vibration Bulletin. Part 2: Modal Test and Analysis, Testing Techniques, Machinery Dynamics, Isolation and Damping, Structural Dynamics; p 1-8
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  • 4
    Publication Date: 2018-06-08
    Description: The Space Technology Research Vehicle (STRV-1b) scheduled to fly at the beginning of June 1994, has a cryocooler vibration suppression experiment aboard doing motion suppression of the tip of the coldfinger. STRV-1b is a bread box sized satellite to be launched on the next flight of the Ariane-4.
    Keywords: Engineering (General)
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  • 5
    Publication Date: 2019-06-28
    Description: The Multiple Boundary Condition Tests (MBCT) approach is evaluated and recent modifications are described. For the application of MBCT, 12 different boundary conditions are selected and the results of applying MBCT in conjunction with a nonlinear formulation are indicated schematically. It is concluded that the nonlinear formulation enhances the ability to implement the MBCT test approach on large space structures which cannot be ground tested without the artificial boundary conditions incorporated in MBCT. In addition, it leads to significant improvements in the convergence to the correct solution.
    Keywords: GROUND SUPPORT SYSTEMS AND FACILITIES (SPACE)
    Type: AIAA PAPER 86-0905
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  • 6
    Publication Date: 2019-06-28
    Description: A major challenge to the structural dynamicist is to validate mathematical models of large space structures which cannot be ground tested because of its size and/or flexibility. The paper presents a Multiple Boundary Condition Test (MBCT) approach which allows a systematic validation of the mathematical model by performing a number of ground tests on a large structure with variable boundary conditions. A numerical simulation is presented which illustrates the validity of the MBCT including some of the potential limitations.
    Keywords: STRUCTURAL MECHANICS
    Type: SAE PAPER 851933
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  • 7
    Publication Date: 2018-06-08
    Keywords: Lunar and Planetary Science and Exploration
    Type: 33rd Annual Precise Time and Time Interval (PTTI) Systems and Applications Meeting; Long Beach, CA; United States
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  • 8
    Publication Date: 2018-06-08
    Keywords: Lunar and Planetary Science and Exploration
    Type: 6th Symposium on Frequency Standards and Metrology; St. Andrews, Scotland; United Kingdom
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  • 9
    Publication Date: 2019-05-29
    Description: Vibration analysis of clustered launch vehicles
    Keywords: STRUCTURAL MECHANICS
    Type: NASA-TN-D-3090
    Format: application/pdf
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  • 10
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    In:  Other Sources
    Publication Date: 2019-06-28
    Keywords: LIFE SCIENCES (GENERAL)
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