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In-Flight Measurements of Dynamic Force and Comparison With Methods Used to Derive Force Limits for Ground Vibration Tests
In-flight measurements of the dynamic forces acting between an aerospace component and its supporting structure have recently been obtained on the Advanced Composition Explorer (ACE) spacecraft.
Vibration test for printed circuit card connectors
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Vibration testing and dynamic studies of relays
Study has been undertaken to determine the separation criteria for a preloaded, idealized set of contacts when they are subjected to a steady-state sinusoidal excitation and when the elasticity of one contact is nonlinear. The study consists of two phases, theoretical and experimental.
A Sinusoidal Pulse Technique for Environmental Vibration Testing
Sinusoidal pulse test method to account for variation of shock spectra with damping
Advantages of multipoint control for vibration testing of complete ranger flight spacecraft
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A unique suspension system for longitudinal vibration testing of large launch vehicles
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Some facets of modal vibration testing
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Multiple shaker system for random vibration testing
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Harness for Vertically Supporting Slender Bodies for Vibration Testing
Support techniques for restraint of slender bodies such as launch vehicles
Acoustic vibration test detects intermittent electrical discontinuities
Nondestructive test method detects faulty electrical connections in inaccessible or hidden portions of electronic harness assemblies and connectors. Method employs readily available commercial equipment.
Survey on vibration tests on missile-like structures and the effects of damping
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Criteria for vibration testing
Systematic application of response spectral analysis and other analyses determine damping sensitivity of flight environment and candidate laboratory tests. Computerized comparison is made between response spectrum for flight environment, or enveloping spectra for collection of flight events, and response spectrum for candidate laboratory test.
Computer-controlled vibration testing
System features quickly achieved steady state, increased accuracy of spectrum definition, and true Gaussian amplitude distribution of resulting signals. Controlled shock-tests might also be tried with this system.
Simultaneous processing of vibration test data
Data from record tracks of all accelerometers is injected simultaneously into electronic circuits which convert inputs into single, composite graphical representation. Three adequate methods of processing data: peak acceleration at a frequency, average of all channels, and quad-mean of all channels.
Development of modified vibration test criteria for qualifying space vehicle components
Simplified methods are described to estimate the test criteria of primary structures at component attachment points subjected to broadband random acoustic excitations. The current method utilizes a constant smeared component mass attenuation factor across the frequency range of interest. The developed method indicates that the attenuation factor is based on a frequency dependent ratio of the mechanical impedances of both the component and primary structures. The procedures used to predict the structural responses are considered as the present state-of-the-art and provide satisfactory prediction results. Example problems are used to illustrate the application procedures of the two methods and to compare the significant difference. It was found that the lower test criteria obtained by the impedance ratio method is due to the results of considering the effects of component/primary structure interaction.
The application of pulse excitation to ground and flight vibration tests
A discussion of the relative merits of sinusoidal versus nonharmonic excitation for flight flutter testing is presented. It is concluded that the use of transient excitation is rapidly becoming a necessity. The application of small-scale rocket motors to the excitation of the aircraft is suggested. The design and development of rocket motors specifically for flight flutter testing is described. Methods of measuring and analyzing the transient response of the aircraft are discussed, and the techniques of theoretically predicting the structural response are described.
Development of modified vibration test criteria for qualifying space vehicle components
The results of the evaluation of two response prediction methods relating to the prediction of structural responses of stiffened shell structures with or without attached components, and subjected to broadband acoustic excitations are presented. The methods under evaluation were the constant mass attenuation method and the impedance ratio method. Example problems were used to illustrate the application procedures of these two methods and to compare their predicted results with the experimentally measured data. It is found that more realistic estimates of the structural response can be obtained by the impedance ratio method.