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Fig. 5.15 shows the overall deformation of the flat layer FDM part, which is, as
already indicated the result of a gross failure of the strands to stay together. It
appears, the flat layers would slide against each other, the moment, and the weak
interlayer connections are snapped. This results in large deformations along the
length of the part, leading to an early plastic failure of the part. The curved layer FDM
part on the other hand, clearly shows a better fusion between individual strands, as
is evident from Fig. 5.16. The strand structure remains intact till the end and the part
deflects and assumes the wavy shape as depicted, due to the central down ward
load and the upward reactions on either ends of the part. As the load gradually
increases, the central portion is bent, the upper strands are compressed and the
lower strands are subjected to tensile loads. Finally, the part fails, when the crack
initiated at the bottom reaches the top, tearing apart the shell like part. The failure
mechanisms observed on most samples of the curved layer FDM models subjected
to three point bending load confirmed the same.
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