dc.description.abstract | Digital Image Correlation is a state-of-the-art technique for experimental measurement
of displacement, strain and indirectly stress of constructions. Aramis software is
developed by GOM based on Digital Image Correlation and implemented in the system
for non-contact optical measurement. Beside the software, the system includes stereo
cameras and lenses. To use the Aramis system, the first requirement is that the surface
is prepared for filming. Preparation of the surface implies that stochastic pattern is
applied to the surface of the object to be deformed (irregular black dots on a white
background), because the system compares the position of points (pixels) before and
after loading and deforming the object. The second requirement is that the system is
calibrated. Both of these requirements don’t require a lot money and time (comparing to
some other methods).
For instance, measurement of construction strain by the method of strain gauges
implies positioning of strain gauges at previously selected critical places, in zones of
stress (and strain) concentration. As a problem with the method of strain gauges, which
is most often used for diagnostics, the positioning of gauge itself is imposed. The gauge
should be placed in zones where there is a large stress change gradient, so the strain
gauge position affects the results a lot. This problem is overcome by using the Aramis
system, which enables the recording of strain over the entire field. So, in the actual
„ Bezbednost, kulturno nasleđe i nove tehnologije “ 2020 - Zbornik apstrakata
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„ Bezbednost, kulturno nasleđe i nove
tehnologije “
Beograd, 31. oktobar, 2020
stress concentration zone virtual strain gauge can be positioned, which measures the
distance between two points before and after the loading.
The first several measurements using the Aramis system (in this research) were
performed by measuring objects using the Aramis system and the strain gauges in
parallel. The objects of observation in those experiments vary from pipe branches to
bucket wheel excavator parts (there are no limitations in terms of the type and material
of the object, although steel structures were mainly examined). In the way of measuring
objects using the Aramis system and the strain gauges in parallel, the Aramis system is
calibrated and could be trusted completely in the future. Later, it was used when other
measurement tools couldn’t, for instance, when the zone of stress concentration is too
small to position a strain gauge, as in stress concentration zone on the locking
compression plates (a hole diameter is less than 4 mm, stress concentration zone less
than 2 mm). It was also used to record a crack growth, and strain in zones near the
crack | sr |