Understanding aging characteristics of a pyrotechnic initiator through performance modeling in Closed Bomb Tests

Abstract

We conducted an analysis of the natural aging characteristics of an electric pyrotechnic initiator stored for 11 years, using 10‐cm3 Closed Bomb Tests (CBTs). For the comparative analysis, we utilized the closed bomb test data from other three batches that were tested 11 years ago when they were produced. Notably, two aged samples exhibited peculiar phenomena in terms of maximum pressure and the time taken to reach it, both of which are the performance indicators of Closed Bomb Tests. The time taken to reach maximum pressure increased in both aged samples compared to the pristine samples. Additionally, while one aged sample demonstrated a higher maximum pressure, the other displayed a significantly lower value compared to the pristine ones. Through statistical analysis of test results from three batches of the reference samples and one batch of aged samples led us to propose the existence of a natural aging effect on the initiator. The increase in time taken to reach maximum pressure compared to the reference samples can be attributed to the phenomenon of an increasing particle size distribution of spherical combustion particles in the present combustion model. Furthermore, the aging of the binder of the initiator charge likely contribute to a relative increase in the size of the combustion particles due to the binder hardening over time. To explain the phenomenon of the pressure initially reaches its maximum value on the CBT pressure‐time curve and subsequently decrease, we introduce the concept of condensation, where the gas phase transitions into liquid and solid phases.