Continuous Stiffness Measurement A
Agilent Nano Indenter G200 User’s Guide A-12
It is also important to note that when the indenter is hanging free (no
contact), K is simply K
s
. Thus, the natural frequency of the indenter
head alone is given by (K
s
/m)
1/2
. For the Nano Indenter G200, the
natural frequency of the indenter head is about 20
Hz; for the Nano
Indenter DCM, the natural frequency of the indenter head is about
120
Hz.
Calculating Continuous Elastic Modulus and Hardness
Once the elastic stiffness of the contact, S, has been determined
continuously using
Equation 42, you may use the equations outlined in
Chapter 7, "Theory" to calculate elastic modulus and hardness as a
continuous function of penetration depth. On most metals, ceramics, and
glasses, good agreement is found between the properties determined
semi-statically (using the slope of the unloading curve) and the
properties determined using CSM.
In Figure A-7, the red circles show the elastic modulus as determined
from the slope of the unloading curves from 10 individual indents on
fused silica. The black diamonds show the elastic modulus calculated
from the dynamic information obtained during the same 10 indentation
experiments. Note good agreement between the data sets.
Figure A-7Elastic modulus using CSM stiffness and stiffness from
unloading slope
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