Shock Tube for Downselecting Material Concepts for Blast Protection. Part I: Description of the Shock Tube and a Comparison of Flush Mounted and Recess Mounted Pressure Sensors

摘要

This report documents Part I of a study on the interaction between shock waves and material systems as part of a U.S. Army initiative to better protect individual Soldiers against novel blast threats. The research was conducted using a shock tube fabricated at the U.S. Army Natick Soldier Research, Development and Engineering Center (NSRDEC). The shock tube was used because it is less expensive than explosive blasts, allows many tests to be obtained in a short time, offers much better repeatability, and can be operated in a laboratory setting. The primary goal of its use was to identify appropriate test procedures and evaluation criteria for the initial screening and down selection of material systems that have potential to provide blast protection, subsequently enabling evaluation of down selected systems in true blast environments. The work reported here was designed to answer some of the questions involved in measuring pressure behind flexible fabrics, such as the effect of sensor mounting (flush mounted versus recessed) and the effect of sample thickness or areal density on the pressure measurement. Several analyses were performed to correlate theoretical calculations with the observed measurements. The results indicate that the shock tube worked properly and that all sensors responded appropriately. The data from this study suggest that careful consideration must be given to appropriate mounting of materials with respect to pressure sensors for measurement. The degree of contact between sensor and material may have a significant effect on results.