Results: Tomography and Morphological Variations
The X-ray computed tomography shows the differences in the external shell of the prints as well as the internal structure of the infill. Each layer of PLA can be easily observed in the images. For simplicity, the most prominent image from among the hundreds of images in the dataset are represented in the Fig. 5-7. The number on their top right corner is the corresponding image taken from the captured dataset. The blue objects were not scanned due to the insufficiency of time and lengthy scanning process. Fig. 5-7 show one of the hundreds of images captured during the CT scan. The difference in the background colors is because of the adjustments made to get a good contrast wherever necessary.
Fig. 5 X-ray CT scanned images of the outer shell of all objects.
Fig. 6 X-ray CT scanned images of the vertical cross section of all objects
Fig. 7 X-ray CT scanned images of the horizontal cross section of all objects
There are very few differences in the morphological structures of the cylinders of either color with the same infill level. There are, however, variation in the way the infill is printed inside the shell of the objects. It is to be noted that in Fig. 6 and Fig. 7, the cross-sectional images with a darker background have a different contrast level than that of the images with lighter background. This happened during image adjustment using the software NRecon, which is used to reconstruct the shadow projections. It does not affect the analysis.
When performing the scans, it might not be possible to capture the entire object as the field of view of the receiver is limited (less than 30 mm). Hence only the top portion of the cone was captured. In the case of the cylinders, again, the top was captured, but since the diameter was around 30mm, the detector could only receive a little over 4/5th of it. So, only a part of the wall can be seen. Again, this does not affect the measurement, as the objects are symmetric about the vertical planes.
References can be found in the Introduction section.