Optical measurement vs conventional displacement measurement tools

[[Is...]]

Hello GOM Forum,

I am trying to compare optical mesurément with that of Conventional measurement tools (Strain gauges, LVDT) in specific areas.

Now in GOM correlate 2D after applying importation of stages, length defination, surface creation........

FOR RESULTS, I am interested in studying displacement/strain of the specimen in Y-direction.

This is how i proceeded in order to get plots

1-Deviation label of Displacement(Y) gives a predicted trend line even though the actual values seems higher than that of the Strain gauge.

2. Deviation label of Epsilon(Y) gives quite a different trend line compared to that of Displacement Y. The computations choosen is epsilon=Delta_L/L(Technical strain)

3. Length change(Y) or Distance(Y) for Extensometers. This gives a similar trend line to that of Epsilon(Y)

Now my question is, Which of these commands is suppose to be used to extract displacement/strain measurement from GOM correlate 2D that corresponds to that of my Strain gauge/LVDT which I coupled to my specimen pior to test execution.

The attached files below may help in better understanding my problem.

Thank you in advance.

ismail.bello@cyu.fr