This article comprises a comprehensive description of pyroshock, the interpretation of pyroshock data, and the validation of pyroshock data. Recent events in the pyroshock testing community show that corrupted pyroshock data are still being taken at both government agencies and private companies. A large part of this article is devoted to the acquisition and analysis of pyroshock data because proper time-history data acquisition and, consequently, test specification development are common industry problems. To avoid corrupted pyroshock data and resulting corrupted pyroshock specifications, recommended practices for instrumentation and data acquisition systems as well as data analyses are given. Causes of corrupted pyroshock data are explored, and recommendations for avoiding corrupted pyroshock data are provided. Pyroshock was once considered a relatively mild environment due to its low-velocity change and high-frequency content. Pyroshock rarely damages structural members, but can easily cause failures in electronic components that are sensitive to high-frequency pyroshock energy. In the near field, pyroshock acceleration is a high-frequency, high-amplitude shock wave that may have transients with a duration of microseconds. 1,2,3,4,5 In the mid field and the far field, the pyroshock acceleration time history approximates a combination of decayed sinusoids with one or more dominant frequencies. 2,3,4,5 Pyroshock or pyrotechnic shock originates from point sources (explosive nuts and bolts), line sources or flexible linear shaped charges (FLSC), mild detonating fuses (MDF), and combined sources (V-band/Marmon clamps). Types of failures caused by pyroshock commonly include relay chatter, separation of small-circuit test items, and dislodging of contaminants (e.g. solder balls) that cause short circuits. 2,3,4,5 Definitions for pyroshock are now uniform in all major documents, as shown in Table 1; this was accomplished during the last four years. 2,3,4,5 These definitions are only guidelines. The most important aspect of these definitions is the frequency specification, because frequency content determines the pyroshock test or simulation. A near-field pyroshock test requires frequency control up to and above 10,000 Hz for amplitudes greater than 10,000 g. A pyrotechnically excited simulation technique is usually appropriate, although in some cases, a mechanically excited simulation technique may be used for small components. 6 A mid-field pyroshock test requires frequency control from 3,000 to 10,000 Hz for amplitudes less than 10,000 g. A mechanically excited simulation technique other that shaker shock is usually required. A far-field pyroshock test requires frequency control no higher than 3,000 Hz for amplitudes less than 1,000 g. A shaker shock or a mechanically excited simulation technique is appropriate. Recent events show that sources of pyroshock data contamination appear to be the usual culprits that have been known for some time-electromagnetic noise (or other noise sources), digital aliasing and offsets...
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