Figure 4. Instron Universal Testing Instrument used for compressive
strength tests. The bottom platen is shown in place while the top platen
is lying on top of the press head.
Pmax = maximum measured force in kg
later converted to SI units. Figure 4 shows the press,
A = initial surface area of the sample in
load cell, motion transducer, and lower platen in place.
cm2.
The upper platen is lying loosely on top of the press
head.
The average strengths of our test series and of the
natural ice we examined are given in Table 2. At the
Results
strain rate we used (about 1.6 102 sec1), the natural
Maximum compressive strength was calculated
ice was clearly in the brittle range while the CFG ice
using the formula
was in the region of flow with cracking. Therefore, the
Pmax
σc =
maximum stress measured for the natural ice was
(1)
A
probably not the maximum possible, while that for the
σc = uniaxial compressive strength in kg/
CFG ice very likely was. However, Hawkes and Mellor
where
cm2, later converted to MPa
(1972), using ice similar to ours, found that the
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