FEM simulation of space instruments subjected to shock tests by mechanical impact

Abstract

Space instruments must be structurally verified to confirm their capability to withstand the severe vibrations and shock environments during the launch phase. The shock loads are caused by the pyrotechnic devices employed for the separation between the launcher stages and for the release of the fairing and the spacecraft. The most recommended verification method for shocks is by testing, which can be performed by different test methods such as electrodynamic shakers, mechanical impact shock machines or pyrotechnic devices. Recently, numerical shock simulations have been incorporated as a part of the structural verification of the space instruments with the aim of providing additional information that cannot be easily obtained from test data. One of most determining aspects to simulate the same environment measured during a shock test by mechanical impact is the definition of the input acceleration, which may be non-uniform and with non-negligible cross levels. The objective of this paper is to propose new techniques that define with precision the input acceleration field measured in the shock test considering the mentioned aspects for the shock simulations by the finite element method. The analyses are performed with the finite element (FE) model of the space instrument STEP of the Solar Orbiter mission and the results are compared with the shock test data to evaluate the improvement of the accuracy achieved from the shock simulations with the different proposed methods.