Abstract
“Regular” linear relations between shock and particle velocities, us = us0, + c · up, imply a divergence of the Hugoniot pressure pH at a critical compression V c/V o = (c-1)/c, where the thermal pressure Δp th = (γ/V)· ΔU th = p H-p T becomes very large with respect to the cold (isothermal) pressure p T at this compression. The Hugoniot relation for the total internal energy U H results in this case in the relation γc = 2(c- 1) for the Grüneisen parameter in this region. Experimental data for the zero pressure value Γo and its derivative Γo together with theoretical data for the limiting value γ∞ = 2/3, and the additional expenmental value γc are then used to determine the thermal (phonon) pressure with the common Mie-Grüneisen assumption.
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