78 A. McGhee and P. Ifju Fig. 11.1 3D printing of speckle plane with syringe and 3D printer into container plunger translation YSM speckle x,y,z syringe translation 60x60mm container 2D speckle plane A60 60 40 mm plastic container, filled with YSM, is large enough for boundary effects to be considered negligible. Since the boundary does not interact with the needle, we can make an infinite plane assumption. A 3D printer is used to insert a 2D plane of polymeric speckles, as well as a white background layer. The same 3D printer used to insert the 2D plane of speckles was used to control the cylinders displacement through the medium. The specimen to be tested was placed on a transparent acrylic surface, and a camera was mounted underneath. A sequence of images were taken as the cylinder is dragged through. These images were then processed using Ncorr (an open source 2D-DIC application for MATLAB) [3]. Using the cylinders location in each deformed image as a reference point, an area around the cylinder was extracted from each deformation measurement. Since the cylinder was at steady state and deforming an infinite plane, all deformation measurements should be the same. By taking many deformation measurements along the path, statistical measurements can be made. 11.3 Results After analysis of each cylinder and speed combination we obtained the u (x-direction) and v (y-direction) displacements as well as a magnitude of displacement plot as can be seen for the 0.81 mm diameter cylinder at 0.1 mm/s in Fig. 11.2. To visualize the effect of velocity and diameter on the displacement away from the cylinder, a plot which shows all speed and diameter combinations is presented in Fig. 11.3. By keeping the scale of the deformation constant in each image, a direct comparison of the effect of velocity and diameter can be seen. By dragging the cylinder back to its initial position and then analyzing the reference image to the total deformation the regions of plastic and elastic deformation can be visualized. 11.4 Discussion The results show high-quality results which measure displacements on the order of 10 m with a deviation of approximately 2 m. By increasing camera resolution and frame rate this technique can easily produce higher quality results than those shown. The technique can also be easily modified to measure out-of-plane distortions by introducing a second camera and a 3D correlation processor. Each deformation field in Figs. 11.2 and 11.3.
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