Looking through books and papers I see an often quoted equation to show that the contact radius (a) of spherical indenter of radius (R) is related to the indentation depth (h):
a= √(R.h)
However, using simple trigonometry of a spherical cap it can be shown that:
a=√(2Rh-h2)
Contact area is very important for use in nanoindentation - however, if it is based on the wrong contact area calculation, then more errors become apparent.
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