Blast (the air shock wave due to explosion) is a major concern due to its ability to cause damage at relatively long distances from the point of explosion ( 10, 11). In general, detonation of a high explosive on or near surface produces blast wave, noise, shrapnel, and toxic gaseous products. Though the generation of shock wave by itself is straightforward, controlling the shape and magnitude of the pressure-time pulse is not trivial, and is subject of the present paper. Since the injury to animals critically depends on the nature of the shock-blast wave (from here on simply known as blast waves), it is important to standardize the blast wave across the various shock tubes. In the study of blast induced neurotrauma (BINT) using animal models, many research groups use compressed-gas-driven shock tubes to simulate primary blast injury conditions ( 4– 9). Such a faithful replication is an essential first step when studying the effects of blast induced neurotrauma using animal models. To conclude, our experimental results demonstrate that a compressed-gas shock tube when designed and operated carefully can replicate the blast time profiles of field explosions accurately.
Also, the shock-blast profiles of a TNT explosion from ConWep software is compared with the profiles obtained from the shock tube.
The effects SAPs have on the resulting shock-blast profiles are shown.
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Forty experiments are carried out by judiciously varying SAPs such as membrane thickness, breech length (66.68–1209.68 mm), measurement location, and type of driver gas (nitrogen, helium). Further, replication of shock profile (magnitude and shape) can be related to field explosions and can be a standard in comparing results across different laboratories. In this work, we examine the relationship between shock tube adjustable parameters (SAPs) and SWPs that can be used to control the blast profile the results can be easily applied to many of the laboratory shock tubes. Furthermore, it is vital to identify and eliminate the artifacts that are inadvertently introduced in the shock-blast profile that may affect the results. It is extremely important to carefully design and operate the shock tube to produce field-relevant SWPs. As shown in some of our recent works ( 1– 3), the profile not only determines the survival of the subjects (e.g., animals) but also the acute and chronic biomechanical injuries along with the following bio-chemical sequelae. The shape and magnitude of the profile determine the severity of injury to the subjects.
These parameters in turn are uniquely determined by the strength of high explosive and the distance of the human subjects from the epicenter. The wave profile is characterized by blast overpressure, positive time duration, and impulse and called herein as shock-blast wave parameters (SWPs). When a pure shock-blast wave encounters the subject, in the absence of shrapnels, fall, or gaseous products the loading is termed as primary blast loading and is the subject of this paper. While direct exposure to blast is a concern near the epicenter, shock-blast can affect subjects, even at farther distances.
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