Research and Technolgoy 1994 Structural Support Skip navigation links

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The Structural Suppport section of the Research and Technology 1994 Annual Report contains this article below, please select the title name to take you right to this article.

Acoustic Fill Effects Test Program Completed

Acoustic Fill Effects Test Program Completed

 Understanding acoustic fill effects for specifying an acoustic environment is critical for payload hardware design and testing. Fill effects is the term used to describe the changes in the interior sound levels of an expendable launch vehicle's (ELV's) payload fairing or the space shuttle's cargo bay caused by the presence of the payload. Often, the acoustic environment defined for the shuttle or an ELV represents the unfilled environment (i.e., the environment expected for an empty cargo bay or payload fairing). It then becomes necessary to account for the presence of the payload fill and its effects on the interior acoustic environment.

Before this test program the fill effects on the acoustic environment were determined from one of three fill factor curves available within the aerospace community. To reduce disputes between multiple organizations involved with a NASA program while maintaining the proper acoustic environments, NASA had to develop a fill effects standard.

illustrations of medium cylindrical, large cylindrical, large square, and stacked cubes test configurations and photograph

Spacecraft payload acoustic test configurations and test setup for
large square spacecraft simulator.

NASA Lewis, in conjunction with General Dynamics Space Systems Division (GDSSD), has completed a test program to investigate the acoustic fill effects for an unblanketed payload fairing. This testing was performed in March 1994 at GDSSD's acoustic test facility. Excellent test data were obtained and used to quantify the effects of payload shape, size, and volume on the acoustic levels for four spacecraft payloads.

The test data were also used to benchmark a statistical energy analysis methodology that can predict the fill effects for any size payload. This methodology has been incorporated into the 1994 NASA standard Payload Vibroacoustic Test Criteria.

Bibliography

Forssen, B.: Test Plan for Measuring Acoustic and Structural Responses of Generic Spacecraft/Nose Fairing Configurations. General Dynamics Space Systems Division, 1994.
Hughes, W.O.; McNelis, M.E.; and Manning, J.E.: NASA LeRC's Acoustic Fill Effects Test Program and Results. NASA TM-106688, 1994.

Lewis contacts: William O. Hughes, (216) 433-2597; Mark E. McNelis, (216) 433-8395
Headquarters program office: OSAT

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