Numerical Modeling of a Pyroshock Test Plate for Qualification of Space Equipment

Over their life, space equipment needs to withstand strong high-frequency shocks, which could cause mission and safety critical damages. In order to verify the compliance with safety standards, pyroshock tests are employed. Based on launch vehicle characteristics, the requirements for the qualification of space equipment are usually established following the NASA-STD-7003A international standards in terms of a Shock Response Spectrum (SRS) representing the damage potential of the shock. Laboratory tests should then match the actual stress conditions reached during a real launch. Historically, this was obtained by means of explosive charges (hence the name “pyroshock”). Nevertheless, to foster repeatability and safety in laboratories, hammers or bullets are commonly used in nowadays shock testing machines. In this work, a resonant fixture test bench is considered. In this very common layout, a resonant metallic plate is interposed between the impact location and the test component so as to better simulate the shocks. The response of the resonant plate - which determines the required shock response spectrum - is currently empirically tuned by adding masses, damping, stiffness, or by varying the nature of the impact. This study aimed at developing a numerical model able to completely simulate a pyroshock test. Such a model can be used both for designing and for tuning the test bench so as to easily match different SRS requirements for different components under test. This leads to great economical advantages as can cut the calibration times leading to more efficient and effective testing.