New simultaneous PVDF/VISAR measurement technique: Applications to highly porous HMX

摘要

Time-resolved pressure and particle velocity measurements provide the foundation for modem descriptions of rate-dependent materials deformation processes in condensed matter subjected to high pressure shock loading. Much of that foundation has been based on the VISAR, nanosecond time-resolved particle velocity technique. It has been known for sometime that full description of the rate-dependent processes requires both particle velocity and stress data, but stress sensors with nanosecond resolution have not been previously available for general usage. More recently, the piezoelectric polymer PVDF has been used for stress and stress-rate measurements in rate dependent materials response experiments. Neither method, by itself, gives unique material response models, particularly in the case of highly porous materials. The first simultaneous, time-resolved measurements with VISAR and PVDF have now been carried out. Measurements were taken on highly porous HMX that clearly show the two-dimensional nature of HMX viscous compression behavior, followed by the onset of chemical reaction. This technique promises to provide a qualitative improvement in our ability to develop rate-dependent material descriptions of all solids including highly porous solids. Precise use of this technique will require new window materials.