Investigation of bending performance of printed continuous carbon fiber reinforced polylactic acid using acoustic emission

In this study, rectangular beams were fabricated by 3D printed continuous carbon fiber reinforced polylactic acid. The effects of deposited space and layer thickness on bending performance are investigated, and the failure modes are analyzed accordingly. At the same time, the acoustic emission technology was applied to test the damage process to facilitate a more in-depth study compared with related studies, and the principal component analysis method and kmeans++ algorithm were applied to analyze the test signal. The results show that the bending strength and modulus of the printed composites decrease correspondingly with the increase of the layer thickness in the range of layer height of 0.7, 0.8, and 0.9 mm. When the fused deposited space is between 0.6 and 0.8 mm, with the increase of the deposited space, the bending strength and modulus also decrease correspondingly. By using principal component analysis, the test signal could be represented by three principal components, and by applying kmeans++ cluster algorithm analysis, the three principal component are divided into five clusters, which correspond to the material failure mode of matrix cracking, interlayer delamination, fiber, and resin debonding, fiber cracking, and fiber fracture. As a result, the bending failure process can be effectively analyzed in detail with the clustering results.