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  • 1
    Publication Date: 2011-08-24
    Description: NASA-Langley and U.S. Army researchers have developed optimization procedures for improving helicopter rotor blade design processes through more extensive integration of the requisite disciplines. These disciplines encompass rotor aerodynamics, rotor dynamics, rotor structures, airframe dynamics, and acoustics. In the first phase of this integrated optimization approach, acoustics and airframe aerodynamics are decoupled and accounted for as effective constraints on the design for the first three disciplines. In phase two, acoustics is integrated with the first three disciplines; in phase three, airframe dynamics are integrated with the other four disciplines. Representative results are presented from recent work on blade shear force reduction and aerodynamic/dynamic optimization.
    Keywords: AERONAUTICS (GENERAL)
    Type: Vertiflite (ISSN 0042-4455); 38; 45-52
    Format: text
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  • 2
    Publication Date: 2011-08-19
    Keywords: AIRCRAFT DESIGN, TESTING AND PERFORMANCE
    Type: Journal of Aircraft (ISSN 0021-8669); 28; 58-65
    Format: text
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  • 3
    Publication Date: 2011-08-19
    Keywords: AIRCRAFT DESIGN, TESTING AND PERFORMANCE
    Type: AIAA Journal (ISSN 0001-1452); 28; 565-567
    Format: text
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  • 4
    Publication Date: 2013-08-31
    Description: In-house analysis work in support of the Control of Flexible Structures (COFS) program is being performed at the NASA Langley Research Center. The work involves evaluation of the proposed design configuration, controller design as well as actuator dynamic modeling, and MAST/actuator dynamic simulation of excitation and damping. A complete finite element model of the MAST has been developed. This finite element model has been incorporated into an optimization procedure which minimizes total mass while maintaining modal coupling. Results show an increase in the total mass due to additional constraints (namely, the diagonal frequency constraint) imposed on the baseline design. A valid actuator dynamic model is presented and a complete test sequence of the proposed flight experiment is demonstrated. The actuator dynamic model is successfully used for damping and the stroke limitations for first mode excitation are demonstrated. Plans are to incorporate additional design variables and constraints into the optimization procedure (such as actuator location) and explore alternative formulations of the objective function. A different actuator dynamic model to include hardware limitations will be investigated.
    Keywords: SPACECRAFT INSTRUMENTATION
    Type: NASA(DOD Control)Structures Interaction Technology, 1986; p 515-532
    Format: application/pdf
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  • 5
    Publication Date: 2013-08-31
    Description: Optimization procedures are developed to systematically provide closely-spaced vibration frequencies. A general purpose finite-element program for eigenvalue and sensitivity analyses is combined with formal mathematical programming techniques. Results are presented for three studies. The first study uses a simple model to obtain a design with two pairs of closely-spaced frequencies. Two formulations are developed: an objective function-based formulation and constraint-based formulation for the frequency spacing. It is found that conflicting goals are handled better by a constraint-based formulation. The second study uses a detailed model to obtain a design with one pair of closely-spaced frequencies while satisfying requirements on local member frequencies and manufacturing tolerances. Two formulations are developed. Both the constraint-based and the objective function-based formulations perform reasonably well and converge to the same results. However, no feasible design solution exists which satisfies all design requirements for the choices of design variables and the upper and lower design variable values used. More design freedom is needed to achieve a fully satisfactory design. The third study is part of a redesign activity in which a detailed model is used.
    Keywords: STRUCTURAL MECHANICS
    Type: Recent Advances in Multidisciplinary Analysis and Optimization, Part 3; p 1459-1488
    Format: application/pdf
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  • 6
    Publication Date: 2013-08-31
    Description: The problem of structural optimization of helicopter rotor blades with integrated dynamic and aerodynamic design considerations is addressed. Results of recent optimization work on rotor blades for minimum weight with constraints on multiple coupled natural flap-lag frequencies, blade autorotational inertia and centrifugal stress has been reviewed. A strategy has been defined for the ongoing activities in the integrated dynamic/aerodynamic optimization of rotor blades. As a first step, the integrated dynamic/airload optimization problem has been formulated. To calculate system sensitivity derivatives necessary for the optimization recently developed, Global Sensitivity Equations (GSE) are being investigated. A need for multiple objective functions for the integrated optimization problem has been demonstrated and various techniques for solving the multiple objective function optimization are being investigated. The method called the Global Criteria Approach has been applied to a test problem with the blade in vacuum and the blade weight and the centrifugal stress as the multiple objectives. The results indicate that the method is quite effective in solving optimization problems with conflicting objective functions.
    Keywords: AIRCRAFT DESIGN, TESTING AND PERFORMANCE
    Type: Recent Advances in Multidisciplinary Analysis and Optimization, Part 1; p 209-233
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  • 7
    Publication Date: 2013-08-31
    Description: Optimization procedures are described for the rotor blade design process by integrating appropriate disciplines and accounting for important interactions among the disciplines. Progress is reported in the areas of aerodynamic performance optimization, dynamic optimization, optimum placement of tuning masses for vibration reduction, and structural optimization. Selected results from these activities are highlighted in this appendix.
    Keywords: AIRCRAFT DESIGN, TESTING AND PERFORMANCE
    Type: Integrated Multidisciplinary Optimization of Rotorcraft: A Plan for Development; p 38-78
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  • 8
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    In:  CASI
    Publication Date: 2013-08-31
    Description: Aerodynamic performance aspects of rotor blade design are presented. Design considerations, aerodynamic constraints and design variables are described.
    Keywords: AIRCRAFT DESIGN, TESTING AND PERFORMANCE
    Type: Integrated Multidisciplinary Optimization of Rotorcraft: A Plan for Development; p 10-13
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  • 9
    Publication Date: 2013-08-31
    Description: Effective design strategies for a class of systems which may be termed Experimental Space Systems (ESS) are needed. These systems, which include large space antenna and observatories, space platforms, earth satellites and deep space explorers, have special characteristics which make them particularly difficult to design. It is argued here that these same characteristics encourage the use of advanced computer-aided optimization and planning techniques. The broad goal of this research is to develop optimization strategies for the design of ESS. These strategics would account for the possibly conflicting requirements of mission life, safety, scientific payoffs, initial system cost, launch limitations and maintenance costs. The strategies must also preserve the coupling between disciplines or between subsystems. Here, the specific purpose is to describe a computer-aided planning and scheduling technique. This technique provides the designer with a way to map the flow of data between multidisciplinary analyses. The technique is important because it enables the designer to decompose the system design problem into a number of smaller subproblems. The planning and scheduling technique is demonstrated by its application to a specific preliminary design problem.
    Keywords: SPACECRAFT DESIGN, TESTING AND PERFORMANCE
    Type: Recent Advances in Multidisciplinary Analysis and Optimization, Part 1; p 297-316
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  • 10
    Publication Date: 2011-08-19
    Keywords: STRUCTURAL MECHANICS
    Type: AIAA Journal (ISSN 0001-1452); 26; 1506-151
    Format: text
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