Development and characterization of an open-ended shock tube for the study of blast mtbi

Shock tubes can be used to study traumatic brain injuries due to blast waves in a laboratory setting without the use of explosives. A literature review shows that several shock tubes used in these type of studies are large in size and have a high cost of conducting tests and maintaining the device. The purpose of this study was to design and characterize small shock tubes to simulate open field blast waves, which can be used in a laboratory with limited space and has low cost of operation. In addition, the shock tube can be used to induce localized blast in a small region to study the injury mechanisms in the desired region. Furthermore, the animal is placed outside of the shock tube, which provides the ability to expose the animal to a pure primary blast wave. A helium-driven shock tube with driven length of 3.04 m and driver length of 0.30 m was used in the present study. Transducers were placed at multiple locations and distances to characterize the blast wave outside the shock tube. The versatile design of the shock tube can generate a wide range of peak overpressure, rise times and durations. The shock tube was able to generate peak overpressure ranging from 25 kPa to 508 kPa and positive durations ranging from 97 µs to 797 µs. The literature review also showed several studies where the data were collected and analyzed improperly. The under-sampling or improper filtering can significantly affect the data. Additionally, the orientation of the transducer with respect to the shock wave can also affect the recorded peak overpressure. This paper reports various peak overpressures, durations and rise-times that can be developed with a small open-ended shock tube and the methodology to properly collect and analyze blast wave data generated by the shock tube.