INTRODUCTION

Pyroshock, also called pyrotechnic shock, is the response of a structure to high-frequency (thousands of hertz), high-magnitude stress waves that propagate throughout the structure as a result of an explosive event such as the explosive charge to separate two stages of a multistage rocket. The term pyrotechnic shock originates from the use of propellants such as black powder, smokeless powder, nitrocellulose, and nitroglycerin in devices common to the aerospace and defense industries. These devices include pressure squibs, explosive nuts and bolts, latches, gas generators, and air bag inflators. ^[1] The term pyroshock is derived from pyrotechnic shock, but both terms are used interchangeably in the industry and its literature. A pyroshock differs from other types of mechanical shock in that there is very little rigid-body motion (acceleration, velocity, and displacement) of a structure in response to the pyroshock. The pyroshock acceleration time-history measured on the structure is oscillatory and approximates a combination of decayed sinusoidal accelerations with very short duration in comparison to mechanical shock described in Part I of this chapter. The characteristics of the pyroshock acceleration time-history vary with the distance from the pyroshock event. In the near field, which is very close to the explosive event, the pyroshock acceleration time-history is a high-frequency, high-amplitude shock that may have transients with durations of microseconds or less. In the far field, which is far enough from the event to allow structural response to develop, the acceleration time-history...