Recent advances in vibroacoustics
Numerous vibroacoustics advances and problems in the aerospace industry have occurred over the last 15 years. This article addresses some of these that developed from engineering programmatic task-work at the NASA Glenn Research Center at Lewis Field.
Effect of structural mount dynamics on a pair of operating Stirling Convertors
The U.S. Department of Energy (DOE), in conjunction with NASA John H. Glenn Research Center and Stirling Technology Company, are currently developing a Stirling convertor for a Stirling Radioisotope Generator (SRG). NASA Headquarters and DOE have identified the SRG for potential use as an advanced spacecraft power system for future NASA deep-space and Mars surface missions. Low-level dynamic base-shake tests were conducted on a dynamic simulation of the structural mount for a pair of Operating Stirling Convertors. These tests were conducted at NASA Glenn Research Center’s Structural Dynamics Laboratory as part of the development of this technology. The purpose of these tests was to identify the changes in transmissibility and the effect on structural dynamic response on a pair of operating Stirling Technology Demonstration Convertors (TDCs). This paper addresses the base-shake test, setup, procedure and results conducted on the Stirling TDC mount simulator in April 2001.
Development of Acoustic Test Criteria for the Cassini Spacecraft
Acoustic measurements from eight Titan IV flights, and an acoustic test of a Cassini simulator and Titan payload fairing (PLF), were used to derive acoustic flight and test criteria for the Cassini spacecraft. The flight and laboratory data were used or modified to account for the following factors: (a) noise-spike contamination of flight data, (b) spatial and flight-to-flight variations of flight data, (c) application of a thicker barrier-blanket to the PLF for the Cassini mission, (d) effects of locating two Cassini assemblies, the Huygens Probe (HP), and the High Gain Antenna (HGA), near the PLF, and (e) higher thrust of upgraded Titan solid rocket motors (SRMs) for the Cassini mission. An overall sound pressure level of 145 dB was verified for the protoflight acoustic test criteria for the Cassini spacecraft.