A foam which I have performed compression tests on shows results similar to the following hysteresis cycle:
(Note that the first bend in the graph is not the yield point; the hysteresis cycle returns to the origin.)
I would like to characterize the compressibility of the material using a commonly used statistic.
The Young's modulus is an obvious candidate (see dotted line), but it doesn't really capture the characteristics of the material when you compress it further.
Instead I had the idea of using the dashed line: the minimal value of stress divided by strain over all values along the curve of the compression. However, I don't know whether that is a commonly used statistic to describe compression of foams.
What commonly used statistic best describes the compression behavior of a foam at higher strain values?