User:S & V Technologies

Pyrotechnic Shock or Pyroshock

Pyroshock also known as Pyrotechnic Shock is the dynamic structural shock that occurs when an explosion or impact occurs on a structure [1]. Davie and Bateman [1] describe it as "Pyroshock is the response of a structure to high frequency (thousands of Hertz), high-magnatude stress waves that propagate throughout the structure as a result of an explosive event such as an explosive charge to separate two stages of a multistage rocket." It is of particular relevance to the defense and aerospace industries in that they utilize many vehicles and/or components that use explosive devices to accomplish mission tasks. Examples include rocket stage separation, missle payload deployment, pilot ejection, automobile airbag inflators, etc. Of significance is the survival and integrity of the equipment after the explosive device has activated so that the vehicle can accomplish its task. There are examples of flight vehicles [Moening-The Aerospace Corp] which have crashed after a routine explosive device deployment, the cause of the crash being determined as be a result of a computer failure due to the explosive device. The resulant energies are often high g and high frequency which can cause problems for electronic components which have small items with resonant frequencies near those induced by the pyroshock.

The structural environment is very high magnitude for a relitively short duration and presents many difficulties to capture faithfully. From full scale, high fidelity pre-runs using actual flight hardware, to actual in-flight data, to simulating the event in the test laboratory, there are many possible pitfalls: instrumentation, signal conditioning, amplification, filtration, data acquisition, data sampling, and analysis. In order to verify defense and aerospace vehicle integrity, pyroshock testing is performed in a controlled laboratory environment.

An excellent overall summary of this science has been written by Davie and Bateman and can be found in Chapter 26, Part II of the Harris' Shock and Vibration Handbook, 5th edition, edited by Cyril Harris and Allan Piersol published by McGraw-Hill.

There are also excellent references found at the IEST-RP-DTE012.2: Handbook for Dynamic Data Acquisition and Analysis [2]

[1] Davie, N.T. and V.I. Bateman "Pyroshock Testing", Harris' Shock and Vibration Handbook, Chapter 26, Part II

[2] Media:http://en.wikipedia.org/wiki/Institute_of_Environmental_Sciences_and_Technology