Development of a New Unreacted Equation of State for LX-17 with a Genetic Algorithm and a Semiparametric Model

Although the insensitive TATB-based explosive LX-17 is a well-studied energetic material, there is surprisingly little shock data from which to build an accurate unreacted equation of state for use with reactive flow models. In this work, we combine the existing Hugoniot data, including overdriven data, with data points derived from Pop Plots to increase the size of our data set and fit a new equation of state to this expanded data set. A semiparametric approach is used to model the equation of state to allow for more flexibility than traditional parametric equations of state. To find the best fit, a genetic algorithm performs a global search for the optimization and uses a fitness function that both minimizes the residual and respects physical constraints. We finally compare our equation of state to the existing unreacted equations of state by examining their Hugoniot curves, their fit to data, and their performance in simulations of sustained pulse shots and the resulting Pop Plots.