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  • 1
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    Composite Structures and Materials Research at NASA Langley Research Center (2003)
    In:  CASI
    Details
    Publication Date: 2018-06-28
    Description: A summary of recent composite structures and materials research at NASA Langley Research Center is presented. Fabrication research to develop low-cost automated robotic fabrication procedures for thermosetting and thermoplastic composite materials, and low-cost liquid molding processes for preformed textile materials is described. Robotic fabrication procedures discussed include ply-by-ply, cure-on-the-fly heated placement head and out-of-autoclave electron-beam cure methods for tow and tape thermosetting and thermoplastic materials. Liquid molding fabrication processes described include Resin Film Infusion (RFI), Resin Transfer Molding (RTM) and Vacuum-Assisted Resin Transfer Molding (VARTM). Results for a full-scale composite wing box are summarized to identify the performance of materials and structures fabricated with these low-cost fabrication methods.
    Keywords: Mechanical Engineering
    Type: Low Cost Composite Structures and Cost Effective Application of Titanium Alloys in Military Platforms; 17-1 - 17-11; RTO-MP-069(II)
    Format: text
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    NASA TECHNICAL REPORTS
  • 2
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    Active Blade Vibration Control Being Developed and Tested (2003)
    In:  CASI
    Details
    Publication Date: 2018-06-05
    Description: Gas turbine engines are currently being designed to have increased performance, lower weight and manufacturing costs, and higher reliability. Consequently, turbomachinery components, such as turbine and compressor blades, have designs that are susceptible to new vibration problems and eventual in-service failure due to high-cycle fatigue. To address this problem, researchers at the NASA Glenn Research Center are developing and testing innovative active blade vibration control concepts. Preliminary results of using an active blade vibration control system, involving a rotor supported by an active magnetic bearing in Glenn's Dynamic Spin Rig, indicate promising results (see the photograph). Active blade vibration control was achieved using feedback of blade strain gauge signals within the magnetic bearing control loop. The vibration amplitude was reduced substantially (see the graphs). Also, vibration amplitude amplification was demonstrated; this could be used to enhance structural mode identification, if desired. These results were for a nonrotating two-bladed disk. Tests for rotating blades are planned. Current and future active blade vibration control research is planned to use a fully magnetically suspended rotor and smart materials. For the fully magnetically suspended rotor work, three magnetic bearings (two radial and one axial) will be used as actuators instead of one magnetic bearing. This will allow additional degrees of freedom to be used for control. For the smart materials work, control effectors located on and off the blade will be considered. Piezoelectric materials will be considered for on-the-blade actuation, and actuator placement on a stator vane, or other nearby structure, will be investigated for off-the-blade actuation. Initial work will focus on determining the feasibility of these methods by performing basic analysis and simple experiments involving feedback control.
    Keywords: Mechanical Engineering
    Type: Research and Technology 2002; NASA/TM-2003-211990
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 3
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    A Comparison Study of Magnetic Bearing Controllers for a Fully Suspended Dynamic Spin Rig (2002)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: NASA Glenn Research Center (GRC) has developed a fully suspended magnetic bearing system for the Dynamic Spin Rig (DSR) that is used to perform vibration tests of turbomachinery blades and components under spinning conditions in a vacuum. Two heteropolar radial magnetic bearings and a thrust bearing and the associated control system were integrated into the DSR to provide noncontact magnetic suspension and mechanical excitation of the 35 lb vertical rotor with blades to induce turbomachinery blade vibration. A simple proportional-integral-derivative (PID) controller with a special feature for multidirectional radial excitation worked very well to both support and shake the shaft with blades. However, more advanced controllers were developed and successfully tested to determine the optimal controller in terms of sensor and processing noise reduction, smaller rotor orbits, and energy savings for the system. The test results of a variety of controllers we demonstrated up to the rig's maximum allowable speed of 10,000 rpm are shown.
    Keywords: Mechanical Engineering
    Type: ISMB-8-Paper-0160 , 8th International Symposium on Magnetic Bearings; Aug 26, 2002 - Aug 28, 2002; Mito; Japan
    Format: application/pdf
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  • 4
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    Adaptive Variable Bias Magnetic Bearing Control (1998)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Most magnetic bearing control schemes use a bias current with a superimposed control current to linearize the relationship between the control current and the force it delivers. With the existence of the bias current, even in no load conditions, there is always some power consumption. In aerospace applications, power consumption becomes an important concern. In response to this concern, an alternative magnetic bearing control method, called Adaptive Variable Bias Control (AVBC), has been developed and its performance examined. The AVBC operates primarily as a proportional-derivative controller with a relatively slow, bias current dependent, time-varying gain. The AVBC is shown to reduce electrical power loss, be nominally stable, and provide control performance similar to conventional bias control. Analytical, computer simulation, and experimental results are presented in this paper.
    Keywords: Mechanical Engineering
    Type: NASA/TM-1998-206975 , NAS 1.15:206975 , E-11127 , 1998 American Controls Conference; Jun 24, 1998 - Jun 26, 1998; Philadelphia, PA; United States
    Format: application/pdf
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