In this application video, a 4-cam (5 Mpx) MulticamDIC system is being used to measure the E-modulus,
strain and thickness of a cast iron bar in a tensile test.The MulticamDIC system is setup in a double-sided / bi-planar configuration, whereby cameras 1 & 2
view the specimen from the front side and cameras 3 & 4 view the specimen from the back side.
A double-sided calibration target is also used to calibrate all the cameras together in one coordinate
system, as such, no image stitching is used. This also allows adjacent points on either face sides to
be accurately determined.In the correlation evaluation, an Object Alignment Parameterization (OAP) is used which aligns the
facets/subsets as an object (biplanar) model, instead of being taken from a camera perspective.
This allows complex shapes to be measured, with much higher measurement accuracy.In the graphical visualization, a 2D-overlay of the engineering principal strain 1 can be seen,
together with line gauges on the front/rear side and a point gauge in the middle. The max major
strain reaches ca. 1100 mstrain. From the temporal plot of the line gauges, it is clear that during
elongation, the thickness between the two faces reduces by ca. 2 mm before fracture. From the
analogue signal (shown in pink), it is clear that “necking” has occurred, in that the peak load of
33,000 N is reached then drops off before fracture.Using the application scripting module, the true stress vs. strain curve can be plotted, since the
thickness is known (from using the biplanar setup). The E-modulus is 135 GPa.
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