Estimating shock spectra: Extensions beyond GEVS

Shock response spectra (SRS) are the standard description of the vibration environment on spacecraft for equipment qualification. For shock events produced by pyrotechnic devices, SRS can have significant frequency content as high as 10 kHz. The General Environmental Verification Standard (GEVS) for GSFC Flight Programs and Projects provides a simple, empirically based method for approximating the SRS. It begins with a base SRS according to the type of pyrotechnic device, and then provides attenuation relations to adjust this SRS according to distance from the shock source, type of structural frame, and the properties of any structural joints between the source and equipment. In this paper we extend this SRS approach to include more detailed information about the spacecraft structure. We show how finite-element mode shapes can be used to explicitly calculate the attenuation relations. The derivations are based on random vibrations and wave concepts. We illustrate the extended GEVS approach with comparisons of experimentally determined SRS from the Solar Terrestrial Relations Observatory (STEREO).