Initiation of a metal/fluoropolymer reactive material subjected to dynamic shear–compression loading

Structural Reactive Materials (RMs) are multi-material composites that provide adequate structural strength and large exothermic yield. Combining the thermal energy output with kinetic energy kinetic energy, RMs fulfill a role in increasing the overall performance and energetic release of military weapon systems. The goal of this current research is to enhance the understanding of the thermomechanical conditions that are responsible for Al/PTFE RM ignition under dynamic loading. Two mechanisms of initiation commonly reported in the literature are shear-induced and crack-induced. In order to investigate the propensity of shear-induced initiation a Shear Compression Specimen (SCS), combined with Kolsky Bar experimentation, was utilized to predominately load the RM specimen in dynamic shear. COMSOL Multiphysics simulations were conducted in conjunction with the experiments to obtain equivalent stress–strain response of the RM so that the work done on the gauge section of the SCS could be quantified. With the implementation of high-speed cameras, the gauge section of the SCS was monitored in order to observe if RM ignition occurred from the dynamic shear loading. The results of the experiments conducted here indicate that fracture precedes ignition despite severe shear-induced plastic deformation (and associated heating) occurring in the gauge section of the specimen, indicating that a crack-induced ignition mechanism is likely active in this materials system under the studied loading rates.