An Alternative to Pyrotechnic Testing For Shock Identification

The ability to produce a repeatable shock spectrum is needed for many applications in industry. Flight components and structural systems often require qualification testing consisting of subjecting the payload to a specified shock response spectrum (SRS). Testing is used to qualify sensitive packages for flight, ensuring that the unit will survive and continue to function normally during and after being subjected to the anticipated environment. Traditional pyroshock testing is expensive, the excitation can over test flight components and it is often not repeatable within desired limits. Furthermore, development of shock isolation systems to reduce environments for flight payloads requires similar testing capability. A compressed-air shock test system has been developed using a pneumatic gun to deliver repeatable and controlled transient loads, simulating high-shock flight conditions. This “shock gun” delivers a captive projectile through a barrel to provide the desired structural response. Measured accelerations are used to quantify the shock performance, typically using the SRS technique. Shock isolation systems have been developed and refined with this system, directed at attenuating high-level, high-frequency loads associated with typical conditions such as launch vehicle fairing and stage separation events. The performance of the present system will be reviewed, and possible extensions of this test method, including ultimate limitations in frequency and amplitude, will be discussed in the paper.