Identification of Pyrotechnic Shock Sources for Shear Type Explosive Bolt

Yanhua Li,Yuan Li,Yuquan Wen,Zhiliang Li,Huina Mu,Xiaogang Li,Shihui Xiong

doi:10.1155/2017/3846236

Abstract

To identify the shock generated sources of shear type explosive bolt, five kinds of explosive bolts with different states, including high preload, low preload, no preload, no piston shear, and only propellant combustion, were designed. The decoupling of four kinds of shock sources, including the collision of propellant combustion, piston shear weak surface, end of piston stroke, and preload release, was realized. Their acceleration responses at 15 cm from the shock source center on 60 cm × 60 cm × 1 cm equivalent aluminum plate were measured by using the piezoresistive accelerometer. On this account, the relative contribution values along with frequency and the mean relative values without regard to frequency of various sources were calculated in high and low preload. Results show that the characteristics of different shock sources are different, and the shock induced by propellant combustion is mainly caused by high frequency, while piston shear and piston impact are concentrated in medium and low frequency. In the high preload condition, the preload release is major contributor to the overall shock response output, accounting for approximately 57.51%, while the contributions of the three shock sources of propellant combustion, piston shear, and piston impact are equivalent, but they are significant contributors in the low preload condition. This study provides design reference to reduce the pyrotechnic shock of shear type explosive bolt.

Highlights

Explosive bolt is a kind of simple, high reliable, and efficient pyrotechnic release devices, widely used in aerospace, missile weapons, and underwater launch system, such as booster rockets separation, stage separation, fairing separation, and the release of external tanks [1, 2]
Due to the randomness of the pyrotechnic incident, there are differences in the acceleration time history and shock response spectrum of the three tests, but the difference is very small, which shows that the samples have good consistency, and the other states are similar
The shock response spectrum of each state is taken as the spectral of three experimental SRS

Summary

Introduction

Explosive bolt is a kind of simple, high reliable, and efficient pyrotechnic release devices, widely used in aerospace, missile weapons, and underwater launch system, such as booster rockets separation, stage separation, fairing separation, and the release of external tanks [1, 2]. Various designs of explosive bolts exist and can be categorized into high explosive type and pressure type [3,4,5,6,7,8]. High explosive type utilizes the shock wave generated by detonation, while pressure type utilizes the high pressure generated by explosion and combustion in the cavity. The pressure type is prevalent because of the advantages: that is, it has relatively lighter shock on installation structure and does not produce fragments and product leakage, namely, noncontamination, and the shear type explosive bolt belongs to this type. As with various pyrotechnic devices, the action of explosive bolt inevitably induces high frequency and high amplitude transient shock, known as pyroshock that can cause failures in nearby electronic, optics, relay, and magnetic components and leads to whole space mission failure [9,10,11]. A general trend appears to reduce the shock level generated by separation device itself

Methods

Results

Conclusion