Shock Wave and Detonics Research
(Energetic Materials Research)

PI:  Dr. Jerry Forbes

In order to computer model the performance of an explosive in various pieces of hardware, an equation of state (EOS) for the explosive material is needed. One of the more commonly used equations of state is the JWL EOS, which can be obtained from a Cylinder Expansion (CYLEX) Test. In this test, a precisely made copper tube is filled with explosive. Once detonated, a streak camera records the diameter of the expanding tube as a function of time. The streak camera film is then digitized, which allows for the diameter of the expanding cylinder to be obtained and used to calculate the JWL EOS of the explosive, using custom software.
Three CYLEX Tests were performed by NSWC-IH in 2011 and then analyzed by ETC. NSWC-IH was given the resulting JWL EOS parameters, excel files containing data analysis and digital film records for all three tests. In addition, the data analysis software developed at ETC was installed on research computers at NSWC-IH and three NSWC-IH employees were trained in its use along with the techniques used in scanning the streak camera films and obtaining the tube expansion data from the scans.
ETC assisted the NSWC-IH Agent Defeat Program with scheduling, organizing, data acquisition and reduction. Assistance was also given to the NSWC-IH reactive material program by way of reactive fragmentation catching and size distribution analysis.
ETC participated in the design of the research plan of the shocked Aluminum/water project. They provided the unreacted Pressure-particle velocity (P-u) curve for the mixture, using a mixture law that requires pressure and kinetic energy equilibration. This P-u Hugoniot was needed to determine the inert free surface velocity as a function of pressure of this mixture when shocked in the extended gap test experiments. The degree of reaction is measured by the amount of free surface velocity in excess of the inert value. ETC assisted in the drafting of a Indian Head Technical Report that will be published in 2012. This report is titled “Explosive Reaction of Aluminum and Water,” IHTR 3234, by Richard Granholm, Richard Lee, Christopher Boswell, Gerrit Sutherland, Thomas McGrath, and Jerry Forbes.

Expanded Modified Gap Test