Pressure and particle velocity measurements in solids subjected to dynamic loading

Abstract

The behavior of a material subjected to dynamic loading conditions should include sufficient information about the major hydrodynamic variables (pressure, volume, and particle velocity) to properly describe an equation of state. Shock speed, a phase component of particle velocity and the easiest characteristic to measure, does not provide sufficient information to serve as the universal experimental diagnostic. Pressure and particle velocity, parameters which yield to relatively accurate experimental measurements, provide direct ties to theoretical studies, as well as to determining tables of coefficients for an equation of state. At the Lawrence Livermore National Laboratory, pressure and particle velocity gauge measurements in both reactive and nonreactive materials are conducted at our large-bore gun facility, where projectiles of up to 1.5 kg reach speeds as high as 2.2 mm/μs. Described here are in-situ foil gauges for both pressure and particle velocity measurements. In addition, the optical Fabry-Perot interferometer for observing particle and free surface velocities in transparent media is discussed. Although these techniques are not new, they have been continuously improved and upgraded at our facility to yield greater accuracy, reliability, and state-of-the-art performance. The emphasis in this paper is on the operational features of the measuring techniques, but examples of experimental results are also included.