37
(see
-d). In order to set a peak load profile, simply click on
“Peak load poking” in the ‘Mode
Selection’ part of the indentation configuration window and define the values acc
ordingly.
Figure 29:
Four modes of control.
3.4.6. Dynamic mechanical analysis - DMA
The Pavone features, besides the quasi-static operation, oscillatory indentations also called dynamic mechanical analysis
(DMA). DMA mode allows mechanical oscillations in all three modes of operation while indenting in a sample and can be
switched ‘On’ in the DMA tab of the corresponding p
rofile menu. Oscillation parameters like frequency, periods, amplitude,
and relaxation time are freely adjustable to provide a flexible measurement design (see Figure 30Figure 31:
). The minimum initial relaxation time should be 5s. However, if the sample shows a long relaxation
duration, the time should be chosen so that equilibrium is reached before DMA starts. Amplitude should
be chosen as small as possible due to the assumption that the contact area does not change during
oscillations and material nonlinearity is not sensed. The frequency range can be chosen between 0.05Hz
up to 20Hz in closed-loop operation and 75Hz in open-loop operation. However, the performance might
a)
b)
c)
d)
