Internal structure of short fiber reinforced thermoplastics manufactured with fused filament fabrication

Due to the layer-by-layer printing nature of fused filament fabrication of short fiber reinforced thermoplastics, the microstructural properties of these materials, such as fiber volume fractions and fiber orientations will be different across different cross-sections or sub-volumes. This study investigates the variability in the internal structure of a glass fiber-reinforced thermoplastic composite by scanning different-sized specimens under X-ray computed tomography. Scanned images are divided into equal-sized sub-volumes that cover the entire volume, either with an exact fit or with overlaps, depending on the size of the sub-volume. Fiber volume fractions and fiber orientations are analyzed over these sub-volumes. Results show that analyzing only 42.2% of the scanned volume provides an estimation of fiber volume fraction around 1% of error. Fiber orientation distributions are determined to be similar between layers of the same printing orientation.