Determining the Equation of State (EoS) Parameters for Ballistic Gelatin

Report No. ARL-TR-7467
Authors: Yolin Huang
Date/Pages: September 2015; 30 pages
Abstract: Ballistic gelatin samples are measured to find their density and the specific heat capacity as a function of temperature. Their volume thermal expansion coefficients, the specific heat capacity ratio (from tests in the range of 20–30 ºC), and the Grüneisen parameter as a function of temperature are calculated from the measured data. These values are used to improve the P-V relationship data, which are then fitted to the Vinet and the Birch-Murnaghan equation of state. However, the fitted curves show low sensitivity of the equations to the derivatives of the bulk modulus. Moreover, the P-V data from the Brillouin scattering measurement show substantial difference to the published shock Hugoniot data. The discrepancies with the shock Hugoniot data hinted toward inaccuracies in the current measured Brillouin scattering data (the longitudinal and the transverse velocities) for this soft material. However, with the density, the sound velocity, the adiabatic bulk modulus, the Grüneisen parameter Γ, and the coefficient S1 (from literature), a set of equations of state can be put together for simulation use.
Distribution: Approved for public release
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Last Update / Reviewed: September 1, 2015