Numerical and experimental study of a pyroshock test set up for small spacecraft components

Abstract

In order to know if specific spacecraft equipment and components will withstand the extremely high accelerations and vibrations due to booster disconnection or stage separation using small explosive charges, small scale pyroshock tests have to be carried out before the actual launching of the spacecraft. With these tests, shock and vibration conditions similar to the conditions encountered during an actual launch are created. In this project pyroshock tests will be simulated in order to compare the simulated accelerations with the experimental ones by means of: 1) Time history signal: The time history is usually described in terms of its absolute peak acceleration and its duration; 2) SRS (Shock response spectrum): The shock spectrum response is the graphical representation of an arbitrary transient acceleration input in terms of how a Single Degree Of Freedom (SDOF) system responds to that input. It is important to know that any transient waveform can be presented as a SRS, but the relationship is not unique; many different transient waveforms can produce the same SRS. As we only track the peak instantaneous acceleration, the SRS does not contain all the information in the transient waveform from which it was created. For example, the curve SRS due to a high acceleration but short duration shock can be achieved by a low acceleration but long duration shock. Both of them would have the same SRS but the damage caused by each one wouldn’t be the same.