Characterization and Modeling of the Dynamic Mechanical Properties of a Particulate Composite Material.

Studying the mechanical response of particle-reinforced polymer composites to dynamic loadings has led to a better understanding of reactions observed for energetic materials from insults well below their shock-initiation threshold. Uniaxial stress and uniaxial strain experiments were conducted at strain rates ranging from quasistatic to 104 sec-1 for a highly filled, HTPB-based, cast-cure, explosive simulant. Analysis of samples recovered from high strain-rate confined compression tests evidenced the fracture of the particulate filler in some of the items. Furthermore, the parameters derived from these experiments, along with a series of numerical simulations using a two-dimensional hydrocode, were used to derive a macroscopic material model consisting of a nonlinear viscoelastic equation of state with linear viscoelastic deviatoric components. This model was validated using inverse impact experiments of "explosive"-filled penetrators and further exercised in simulations of generic explosive-filled penetrators impacting hardened targets at various velocities. Such a model is also a valuable tool for studying the response of propellant and explosive-filled hardware in accident scenarios which might occur during transport and handling.