Accession Number : ADP004707

Title :   A Comparison of Measured Spacecraft Modal Damping Values,

Corporate Author : CALIFORNIA INST OF TECH PASADENA

Personal Author(s) : Wada,B. K. ; Chen,J. C.

Report Date : NOV 1984

Pagination or Media Count : 7

Abstract : The presentation summarized the experiences at the Jet Propulsion Laboratory in the prediction and the measurement of modal damping values of spacecrafts for use in the determination of design loads. The initial recognition of the uncertainty in the prediction of damping and the direct dependence of damping on the design loads when subjected to slowly swept sinusoidal input resulted in an effort to use realistic transient forcing functions. Experiences in the solution of complex eigenvalue response solutions resulting from modal synthesis of subsystems, each subsystem assigned modal damping values, were also discussed. Damping data on both the Voyager and the Galileo spacecrafts using up to 8 different types of techniques to analyze modal data were presented. The preliminary conclusions are that difficulty exists in estimating the true damping of a structure and the measured damping values are dependent on the analysis method of the data. A large quantity of damping data is available and further analysis and evaluation is warranted in order to help predict damping and establish the confidence in the measured damping values. (Author)

Descriptors :   *DAMPING, *SPACECRAFT, *BIBLIOGRAPHIES, PREDICTIONS, MEASUREMENT, VALUE, AERODYNAMIC LOADING

Distribution Statement : APPROVED FOR PUBLIC RELEASE