In this application video, a 3-cam 5 Mpx FlexDIC system is used to measure the principal (major) strain 1
of a 3D-printed Coupon with 3-Centric-Hole in a tensile test with Istra4D V4.12.
In the live setup acquisition mode, the Camera (Position) Name Overlay is available that allows users to
custom-define the camera name and display its position in the visualization window (particularly helpful for
MulticamDIC setups). The force input is taken from a load cell which is connected to one analogue input channel
(ai0) on the Data Acquisition Controller (DAQ). The signal is scaled, labelled and saved together with the acquired
HDF5 image data, which effectively prevents the image, the image’s metadata and analogue data from being
separated from one another. Using the Analogue Inter-Step Sampling (AISS) function, the analogue data is sampled
between successive frames – at 32 times that of the acquisition frame rate. Each analogue channel can also be
independently sampled.
Another feature in V4.12 is the Facet Selection Save Function in the Speckle Pattern Quality Evaluator. This allows
users to save the facet as selected in the quality evaluator for future import directly into the correlation evaluation.
Using the recording procedure editor, every 3rd frame at the current acquisition speed of 5 fps is saved – until 500
frames have been acquired.
In the correlation evaluation, the steps to be correlated are selected based on the saved load values, whereby any
step with a load value <26 N is selected and omitted.
Using the Central Reference Camera Perspective (CRCP), the definition of the reference subset/facet shape can be
selected in any of the three cameras. The central or middle camera serves as the best reference for the reference
subset/facet shape definition since it is most perpendicular (no stereo angle) to the object and as such, the
subset/facet shape is least distorted. This allows larger FoVs and objects of higher curvature &/or complex geometries
to be measured. Additionally, using the CRCP concept the measurement accuracy is 30%
higher compared to a 2-camera solution.
In the graphical visualization, the 2D-overlay of the total displacement with rigid body motion removed (RBMR)
(in microns) can be seen as 1.1 mm. A temporal plot is also created using a virtual line gauge of the engineering
line strain (in mstrain). It is clear that the force peaks at 780 N and then drops away before complete fracture occurs.
The 2D-overlay of the Engineering principal strain 1 (in mstrain) returned a max strain of 100 mstrain around the
3-centric-hoies.
Tensile Test of a 3D-printed Coupon with 3-Centric-Holes using Istra4D V4.12
To learn more about how Dantec Dynamics can help you solve your testing challenges, contact us today.
