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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.
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Brief ground tests were made to determine the effect of reduction of valve friction in a power control system of a fighter airplane by use of a vibrator. The vibrator was found to be an effective means of overcoming adverse effects of valve friction on the control characteristics.
The Adaptive Compliant Trailing Edge demonstrator was a joint task under the Environmentally Responsible Aviation Project in partnership with the Air Force Research Laboratory and FlexSys, Inc. (Ann Arbor, Michigan), chartered by the National Aeronautics and Space Administration to develop advanced technologies that enable environmentally friendly aircraft, such as continuous mold-line technologies. The Adaptive Compliant Trailing Edge demonstrator encompassed replacing the Fowler flaps on the SubsoniC Aircraft Testbed, a Gulfstream III (Gulfstream Aerospace, Savannah, Georgia) aircraft, with control surfaces developed by FlexSys, Inc., a pair of uniquely-designed, unconventional flaps to be used as lifting surfaces during flight-testing to substantiate their structural effectiveness. The unconventional flaps consisted of a main flap section and two transition sections, inboard and outboard, which demonstrated the continuous mold-line technology. Unique characteristics of the transition sections provided a challenge to the airworthiness assessment for this part of the structure. A series of build-up tests and analyses were conducted to ensure the data required to support the airworthiness assessment were acquired and applied accurately. The transition sections were analyzed both as individual components and as part of the flight-test article assembly. Instrumentation was installed in the transition sections based on the analysis to best capture the in-flight aeroelastic response. Flight-testing was conducted and flight data were acquired to validate the analyses. This paper documents the details of the aeroelastic assessment and in-flight response of the transition sections of the unconventional Adaptive Compliant Trailing Edge flaps.
Hybrid gears have been tested consisting of metallic gear teeth and shafting connected by composite web. Both free vibration and dynamic operation tests were completed at the NASA Glenn Spur Gear Fatigue Test Facility, comparing these hybrid gears to their steel counterparts. The free vibration tests indicated that the natural frequency of the hybrid gear was approximately 800 Hz lower than the steel test gear. The dynamic vibration tests were conducted at five different rotational speeds and three levels of torque in a four square test configuration. The hybrid gears were tested both as fabricated (machined, composite layup, then composite cure) and after regrinding the gear teeth to the required aerospace tolerance. The dynamic vibration tests indicated that the level of vibration for either type of gearing was sensitive to the level of load and rotational speed.
Resonant frequencies, mode shapes, and vibrational damping characteristics of Saturn S- I stage model
Mercury-oil pool as gravity reference system, and evaluation of vibrations in various parts of building used for housing pool
Longitudinal vibration of ring stiffened cylindrical shells containing liquids for application to liquid fueled space vehicle boosters
Static-equivalent load approach to designing structures for vibration environment
Hydraulic support system for free-flight simulation with Saturn V-Apollo vehicle, discussing stability requirements, upper bounds of system design, conversion from nonlinear to linear model, etc
Vibration and thermal radiation effects on filter wedge infrared spectrometer used in spacecraft studies of planetary atmospheres
Vibration response of Apollo shell structures to acoustic and aerodynamic noise
Hydraulic support system for free flight simulation with Saturn V-Apollo vehicle, discussing stability requirements, upper bounds of system design, conversion from nonlinear to linear model, etc
Combined static and dynamic loads interactions during phases of flight vehicle operation, noting implications for component vibration failure tests
System suppresses spurious sinusoidal responses of any sinusoidally driven amplifier showing time-dependent phase shift versus frequency function. System is applicable to any sinusoidally driven amplifier. Technique eliminates, or reduces, unwanted spurious vibrations during tests to determine dynamic frequency responses of mechanical systems.
Vibration isolation tests of spring, hysteresis, and magnetic suspension systems for spaceborne telescopes
Guidelines of the methods and applications used in vibration technology at the MSFC are presented. The purpose of the guidelines is to provide a practical tool for coordination and understanding between industry and government groups concerned with vibration of systems and equipments. Topics covered include measuring, reducing, analyzing, and methods for obtaining simulated environments and formulating vibration specifications. Methods for vibration and shock testing, theoretical aspects of data processing, vibration response analysis, and techniques of designing for vibration are also presented.
This paper provides a brief summary of applications of optical holography and holographic interferometry to applied solid mechanics. Basic equations commonly used in fringe interpretation are described and used to reduce the data contained on holographic interferograms. A comparison of data obtained holographically with analytical prediction is given wherever possible. Applications contained herein include front surface physics, study of bomb breakup, transverse wave propagation, study of mode shapes of panels at elevated temperatures, nondestructive testing, and vibration analysis.
An experimental investigation for estimating the nonlinearity of a diagnostic object was carried out on a single-stage, spur gear reducer. The linearity of the properties of spur gearing (including the linearity of its mode of operation) was tested. Torsional vibrations of the driven wheel and transverse (to the meshing plane) vibrations of the drive wheel on its support were taken as the two outputs of the object to be analyzed. The results of the investigation showed that the degree of nonlinearity of a reducing gear is essentially connected with its operating mode, so that different mathematical models of it can correspond to different values of the system parameters.
The properties and peculiarities of two groups of measuring systems reacting to vibrations are discussed. Specifically, results of the action of a three dimensional, cophasal, monoharmonic vibration on the linear system of a measuring instrument was analyzed. Data are also given on the connection between vibration sensitivity and vibration resistance for instruments, methods for estimating vibration resistance, and formulas for expressing test results of vibration resistance. Experimental data are also given for decreasing errors in nonlinear systems during vibrations.