Chris Hughes

Modeling violent reaction following low speed impact on confined explosives

To ensure the safe storage and deployment of explosives it is important to understand the mechanisms that give rise to ignition and reaction growth in low speed impacts. The High Explosive Response to Mechanical Stimulus (HERMES) material model, integrated in the Lagrangian code LSDYNA, has been developed to model the progress of the reaction after such an impact. The low speed impact characteristics of an HMX based formulation have been examined using the AWE Steven Test. Axisymmetric simulations of an HMX explosive in the AWE Steven Test have been performed. A sensitivity study included the influence of friction, mesh resolution, and confinement. By comparing the experimental and calculated results, key model parameters which determine the explosives response in this configuration have been identified. The model qualitatively predicts the point of ignition within the vehicle. Future refinements are discussed.