On the use of thermal quadrupole to simulate the response of a high explosive cylinder to a slow thermal aggression

Slow cook-off is, among other aggressions, one type of solicitation that is highly studied to ensuring ammunition safety. Indeed, under this type of aggression, a high explosive tends to produce a reaction much more violent than under a fast cook-off.

To study and improve knowledge of these phenomena, an experimental-numerical methodology has been developed. First, chemical kinetic of energetic material is determined with differential scanning calorimetry (DSC). Then, these parameters are validated by comparing experimental data obtained with controlled thermal aggression tests and numerical results.

To perform accurate simulations, a new numerical approach based on the quadrupoles method has been developed. Created in 1921, recent improvements to simulate heat transfer with source terms allow the possibility of solving multi-layers problems involving energetic materials. Its main advantage is its analytical / semi-analytical nature. Indeed, it consists of transforming a temporal problem into the Laplace or the Fourrier domains, solving heat transfer equations analytically, and then performing an inverse transform (often numerically) to return to the temporal domain. This technique allows us to circumvent classical drawbacks of purely numerical methods. It is a simple tool well suited to sensitivity studies and system optimisation problems. It can also be easily reversed to estimate contact resistances and diffusivities.

We are currently pursuing the development of the code by implementing the reactional aspect of the high explosive.