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  • 1
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    Fiber shape effects on metal matrix composite behavior (1992)
    In:  Other Sources
    Details
    Publication Date: 2011-08-24
    Description: The effects of different fiber shapes on the behavior of metal matrix composites is computationally simulated. A three-dimensional finite element model consisting of a group of nine unidirectional fibers in a three by three unit cell array of a SiC/Ti-15-3 metal matrix composite is used in the analysis. The model is employed to represent five fiber shapes that include a circle, an ellipse, a kidney, and two different cross shapes. The distribution of stresses and the composite material properties, such as moduli, coefficients of thermal expansion, and Poisson's ratios, are obtained from the finite element analysis using the various fiber shapes. Comparisons of these results are used to determine the sensitivity of the composite behavior to the different fiber shapes. In general, fiber dominated properties are not affected by fiber geometry and matrix dominated properties are only moderately affected.
    Keywords: COMPOSITE MATERIALS
    Type: In: International SAMPE Symposium and Exhibition, 37th, Anaheim, CA, Mar. 9-12, 1992, Proceedings (A93-15726 04-23); p. 378-389.
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  • 2
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    Optimum horizontal guidance techniques for aircraft (1978)
    In:  CASI
    Details
    Publication Date: 2006-03-02
    Description: Some problems of automatic guidance of an aircraft in the horizontal plane are described. The horizontal guidance tasks, which such a flight control system should be capable of performing, were identified as being of three types: guiding the aircraft from any initial location and initial heading to (1) any final location and heading; (2) intercept and fly along a line of specified direction; and (3) a final location with arbitrary final heading. Guidance problems such as capturing an ILS beam at a specified point on the beam, intercepting a VOR radial, and point-to-point navigation can be formulated in terms of these problems. The guidance laws minimize the arc distance to fly between initial and final conditions subject to constraints on the minimum turning radius.
    Keywords: AIRCRAFT COMMUNICATIONS AND NAVIGATION
    Type: NASA, Washington Fourth Inter-Center Control Systems Conf.; p 175-184
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  • 3
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    Mixing four-dimensional equipped and unequipped aircraft in the terminal area (1985)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Keywords: AIRCRAFT COMMUNICATIONS AND NAVIGATION
    Type: Journal of Guidance, Control, and Dynamics (ISSN 0731-5090); 8; 296-303
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  • 4
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    METCAN demonstration manual, version 1.0 (1992)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: The various features of the Metal Matrix Composite Analyzer (METCAN) computer program to simulate the high temperature nonlinear behavior of continuous fiber reinforced metal matrix composites are demonstrated. Different problems are used to demonstrate various capabilities of METCAN for both static and cyclic analyses. A complete description of the METCAN output file is also included to help interpret results.
    Keywords: COMPOSITE MATERIALS
    Type: NASA-TM-105607 , E-6944 , NAS 1.15:105607
    Format: application/pdf
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  • 5
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    Metal matrix composite analyzer (METCAN) user's manual, version 4.0 (1992)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: The Metal Matrix Composite Analyzer (METCAN) is a computer code developed at Lewis Research Center to simulate the high temperature nonlinear behavior of metal matrix composites. An updated version of the METCAN User's Manual is presented. The manual provides the user with a step by step outline of the procedure necessary to run METCAN. The preparation of the input file is demonstrated, and the output files are explained. The sample problems are presented to highlight various features of METCAN. An overview of the geometric conventions, micromechanical unit cell, and the nonlinear constitutive relationships is also provided.
    Keywords: COMPOSITE MATERIALS
    Type: NASA-TM-105244 , E-6571 , NAS 1.15:105244
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  • 6
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    The use of curvilinear fiber format to improve buckling resistance of plates with central circular holes (1990)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: The potential gain in buckling resistance is explored by using the curvilinear format with a plate containing a centrally located circular hole and subjected to a uniaxial compressive load. The buckling loads for a uniform stress loading and simple support boundary conditions were examined. The method of analysis is outlined for the buckling improvement study. Several designs that represent an improvement over a baseline quasi-isotropic design (a design that is quite good for buckling resistance) are discussed. The tensile load of these designs is examined. A recommended design is presented that not only shows an improved buckling capacity, but also shows improved tensile performance. Follow-on activities are also discussed.
    Keywords: COMPOSITE MATERIALS
    Type: NASA. Langley Research Center, Eighth DOD(NASA)FAA Conference on Fibrous Composites in Structural Design, Part 1; p 167-178
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  • 7
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    Time controlled descent guidance algorithm for simulation of advanced ATC systems (1983)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Concepts and computer algorithms for generating time controlled four dimensional descent trajectories are described. The algorithms were implemented in the air traffic control simulator and used by experienced controllers in studies of advanced air traffic flow management procedures. A time controlled descent trajectory comprises a vector function of time, including position, altitude, and heading, that starts at the initial position of the aircraft and ends at touchdown. The trajectory provides a four dimensional reference path which will cause an aircraft tracking it to touchdown at a predetermined time with a minimum of fuel consumption. The problem of constructing such trajectories is divided into three subproblems involving synthesis of horizontal, vertical, and speed profiles. The horizontal profile is constructed as a sequence of turns and straight lines passing through a specified set of waypoints. The vertical profile consists of a sequence of level flight and constant descent angle segments defined by altitude waypoints. The speed profile is synthesized as a sequence of constant Mach number, constant indicated airspeed, and acceleration/deceleration legs. It is generated by integrating point mass differential equations of motion, which include the thrust and drag models of the aircraft.
    Keywords: AIRCRAFT COMMUNICATIONS AND NAVIGATION
    Type: NASA-TM-84373 , A-9372 , NAS 1.15:84373
    Format: application/pdf
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  • 8
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    Algorithm for fixed-range optimal trajectories (1980)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: An algorithm for synthesizing optimal aircraft trajectories for specified range was developed and implemented in a computer program written in FORTRAN IV. The algorithm, its computer implementation, and a set of example optimum trajectories for the Boeing 727-100 aircraft are described. The algorithm optimizes trajectories with respect to a cost function that is the weighted sum of fuel cost and time cost. The optimum trajectory consists at most of a three segments: climb, cruise, and descent. The climb and descent profiles are generated by integrating a simplified set of kinematic and dynamic equations wherein the total energy of the aircraft is the independent or time like variable. At each energy level the optimum airspeeds and thrust settings are obtained as the values that minimize the variational Hamiltonian. Although the emphasis is on an off-line, open-loop computation, eventually the most important application will be in an on-board flight management system.
    Keywords: AIRCRAFT COMMUNICATIONS AND NAVIGATION
    Type: NASA-TP-1565 , A-8003
    Format: application/pdf
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  • 9
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    Characteristics of constrained optimum trajectories with specified range (1978)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: Necessary conditions of optimality are derived for trajectories whose structure is limited to climb, steady cruise, and descent segments. The performance function consists of the sum of fuel and time costs, referred to as direct operating cost (DOC). The state variable is range to go and the independent variable is energy. In this formulation a cruise segment always occurs at the optimum cruise energy for sufficiently large range. At short ranges (500 n. mi. and less) a cruise segment may also occur below the optimum cruise energy. The existence of such a cruise segment depends primarily on the fuel flow vs thrust characteristics and on thrust constraints. If thrust is a free control variable along with airspeed, it is shown that such cruise segments will not generally occur. If thrust is constrained to some maximum value in climb and to some minimum in descent, such cruise segments generally will occur. Computer calculations of typical short-range trajectories obtained about a 1% cost penalty for constraining the thrust.
    Keywords: AIRCRAFT COMMUNICATIONS AND NAVIGATION
    Type: NASA-TM-78519 , A-7592
    Format: application/pdf
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  • 10
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    METCAN verification status (1990)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: The status of the verification (comparisons of predictions with experimental data) of the METCAN (METal-matrix Composite ANalyzer) code at high temperature is summarized. Verification includes select available room temperature of W/Cu composites for different fiber volume ratios. It also includes high temperature properties for thermal expansion, moduli, strength and stress/strain behavior for SiC/Ti composites. Furthermore it includes limited cases for thermal fatigue strength degradation. The verification results summarized herein indicate that METCAN simulates complex high temperature metal matrix composite bahavior with reasonable accuracy and that it can be used with confidence to identify in-situ nonlinear behavior that influences composite properties.
    Keywords: COMPOSITE MATERIALS
    Type: NASA-TM-103119 , E-5443 , NAS 1.15:103119
    Format: application/pdf
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