Development of bellows-based low-shock stage separation mechanisms

Abstract This paper presents a comprehensive experimental investigation into the shock characteristics associated with a low-thrust, low-shock separation mechanism incorporating Mild Detonating Cord (MDC) within a rubber bellow interface. Two test configurations were developed with varying explosive charge masses to study their influence on pressure generation and shock propagation. Linear accelerometers and high-speed pressure transducers were employed to capture transient dynamic responses at both piston and cylinder interfaces. The results demonstrate a significant reduction in peak pressure and shock levels, especially in the second test configuration, where the explosive mass was reduced to 60% of the initial configuration. The shock response spectrum (SRS) analysis confirms that the lower charge mass leads to proportionally reduced shock amplitudes across the frequency range of interest. Furthermore, comparative assessment of shock levels reveals a significant reduction of shock levels as compared to conventional separation mechanisms, such as a flexible linear-shaped explosive charge (FLSC) mass or a separation bolt actuated with a pyro cartridge. The experimental pressure values are shown to correlate well with theoretical predictions, validating the design approach. These findings provide critical insights into tailoring explosive-based separation mechanisms for sensitive payload environments, highlighting the importance of confined detonation and charge optimisation in mitigating pyroshock.