Transmission of Sound and Vibration to a Shroud-Enclosed Spacecraft

Abstract

The flow of high-frequency vibratory energy to a shroud-enclosed spacecraft is discussed. Two paths of energy flow are considered: first, the acoustical path along which energy flows from the external exciting field through the shroud and interior acoustic space to the spacecraft; and, second, the mechanical path along which energy flows from the external field through the shroud and spacecraft mounting trusses to the spacecraft. Theoretically predicted response levels in octave frequency bands for a model of the OGO spacecraft assembly are presented. These predictions show that the spacecraft response to energy transmitted along the acoustic path is at least a factor of 10 greater than the response due to energy transmitted along the mechanical path over the frequency range 250–8000 Hz. Methods to reduce the spacecraft response are discussed. [Research supported by National Aeronautics and Space Administration.]

Prediction of vibroacoustic transmission characteristics through double-plate floor structures by using finite-difference time-domain analysis

“…The time development of the vibration is calculated step by step by using the discrete equations composed of the basic equations Eqs. (1), (2), and the continuity conditions of Eqs. (3), (4), (5) and (6).…”

“…To predict such structure-borne sound transmission, for example, the energy-based method such as the statistical energy analysis method [1] has been applied to aerospace engineering [2], investigations of structure-borne sound on ships [3,4], and architecture [5]. The method is also applied to a practical case study on the prediction of structureborne sound in a building [6] by Craik et al In contrast, numerical techniques, such as the finite element method (hereafter called FEM), boundary element method, and finite difference method, have been also applied to prediction of the wave motion in the sound and vibration fields.…”

Random Noise and Vibration in Space Vehicles

“…The major purpose of the structural model is to predict the excitation of that part of the structure directly exposed to the environment. Frequently, however, one is also concerned about mechanical and acoustic energy transmitted to interior portions of the vehicle [7]. Structural models for transmission generally require a more subtle design than those designed for response only.…”

Finite-difference time-domain analysis of the vibration characteristics of a beam-plate structure using a dimension-reduced model

“…Previously proposed structureborne sound prediction methods can generally be classified into two categories: energy-based methods and wave-based methods. Energy-based methods include practical methods using empirical formulas [1,2] and statistical energy analysis (SEA) [3], which is used to predict structure-borne sound in aerospace engineering [4], ship structures [5], and architecture [6,7]. SEA is easily applied to the higher-frequency range without any limitation.…”