Method of vibration power spectral density calculation for spacecraft attached large-size and small-mass equipment units

Abstract

During the lift-off and the ascent phase, spacecraft (SC) large-size attached equipment is impacted by intensive vibrations, largely due to acoustic pressures. To ensure a reliable in-orbit operation of all SC systems the modes of vibration loads shall be assessed as much as reliable (using experimentally-confirmed mathematical models). Determination of the vibroacoustic response parameters of the equipment structure is a very important issue for such equipment units (elements) which have a large surface square with a relatively small mass. Among such structures are folded solar arrays (SA) and reflector type antennae dishes (ART). The purpose of this study is to validate the calculation methodology of vibration power spectral density (PSD) for low and medium frequency band (25-400 Hz), and apply it for the aforesaid structures in the lift-off and flight phases as part of the integrated launch vehicle in the area of maximum ram effects, when the acoustic pressure levels, and therefore their impact on the vibroacoustic response of these structures are maximum. The target goal has been implemented using the example of the solar array and reflector type antenna being used in the spacecraft power supply system and onboard radio system of one of RSC Energia-developed spacecraft. Key words: environment air, spacecraft, solar array, reflector type antennae dish, dynamic model, sound pressure level, acoustic pressure, structure vibroacoustic response.