In this application video, a 3-cam (5 Mpx) TestDIC system is used to measure the deformation and strain of a
polycarbonate coupon sample undergoing a tensile test. The sample is loaded from 0 N to 1500 N.
The TestDIC is a fixed setup system whereby the cameras are permanently mounted, and the lenses are fixed
in both focus and aperture. This removes the need to perform any adjustment of the camera and/or lenses.
It also relinquishes the need to calibrate the projection, each time, before a new test setup is used. Two laser
pointers are used to aid the user in adjusting the correct distance-to-object (DtO). At the point of intersection
between the two laser pointers, the correct distance and point of focus has been set. A real-time overlay of the
speckle pattern quality can be seen, indicated the standard deviation with respect to a selected facet/subset size.
In the measurement, the acquisition speed/camera frame rate of 15 Hz is selected. After acquisition of the
measurement images, the correlation evaluation is performed whereby the central camera is selected to be
the reference camera, known as the Central Reference Camera Perspective (CRCP). This approach defines
the facet/subset generation on the camera with the lowest stereo angle, reducing perspective distortion,
and maximizing both in-plane sharpness and out-of-plane depth-of-field (DoF). It also improves measurement
accuracy by 30%, as opposed to using a 2-camera setup.
In the graphical visualization, the total displacement (in um) with rigid body motion removed, can be seen.
At 1500N, the total displacement was ca. 1.7 mm and eng. strain was 14 mstrain, as shown in the temporal
plots of the virtual line gauge
Tensile test of a polycarbonate coupon sample using the TestDIC system in Istra4D V4.11
To learn more about how Dantec Dynamics can help you solve your testing challenges, contact us today.
