Development and validation of the JWL Equation of State for PE9 used in blast modelling

Abstract

The accumulation of aged and unstable ammunition poses a significant safety and logistical challenge, necessitating controlled disposal methods. Open detonation, a commonly employed technique, requires precise knowledge of the explosive properties to ensure effectiveness and safety. Accurate blast modelling is therefore essential for planning and execution. Central to blast modelling is the Jones-Wilkins-Lee (JWL) Equation of State (EOS), which characterises the pressure-volume relationship during detonation. However, not all commercial explosives have established JWL parameters, limiting their application in simulations and risk assessments. This dissertation focuses on Plastic Explosive 9 (PE9), for which no parameterised JWL EOS currently at the time of writing exists. These parameters were derived by conducting controlled detonation tests using copper cylinder configurations and were recorded with ultra-high-speed shadowgraph imaging. Image processing techniques were applied to track the radial expansion of the copper tubes, and the resulting data was used to calibrate the JWL EOS parameters for PE9. The derived parameters were then validated using LS-Dyna simulations and benchmarked against literature data from well characterised explosives such as Composition B. The results demonstrate strong correlation and consistency with a deviation of only 2.88% for the expansion rate and only 0.004% for the peak pressure, supporting the reliability of the CSIRdeveloped methodology. Future work with optimized equipment is expected to further enhance the precision of these results.