shifted on the time axis in order to display them on the same plot. A spall event, identified by an arrow in Fig. \[fig:freesurfacevelocities\], was recorded for each test. As expected, an increase in the impact velocity resulted in greater shock pressures and peak free surface velocities. Similarly, experiments with aluminum flyers generated greater shock pressures than those with PMMA flyers at equivalent impact velocities due to the difference in the shock impedances of the materials. In general, greater impact velocities also led to greater strain rates.

  ------ -------- ------------------ ---------- ---------------- ---------------- ------------------ ---------------- ------------------------ ------------------ ----------------
  Shot    Target   $w_{\mathrm{l}}$    Flyer     $w_\mathrm{f}$   $v_\mathrm{i}$   $u_\mathrm{max}$   $P_\mathrm{h}$   $\Delta u_\mathrm{fs}$   $\dot{\epsilon}$   $P_\mathrm{s}$
  No.     Liquid         (mm)         Material        (mm)              ()                ()                ()                   ()                 ($10^4$)             ()
  1       0.5 St          13          Al 6061         4.8              124               203               120                   54                   1.1                26
  2       0.5 St          14            PMMA          1.6              445               265               166                   53                   2.4                25
  3       0.5 St          9             PMMA          1.6              628               439               314                   39                   3.7                19
  4       0.5 St          17          Al 6061         6.3              395               540               413                   57                   2.4                27
  5       0.5 St          13          Al 6061         4.8              402               574               450                   48                   3.0                23
  6       0.5 St          9           Al 6061         4.1              387               598               475                   46                   2.3                22
  7       0.5 St          