Flexural damage and failure behavior of 3D printed continuous fiber composites by complementary nondestructive testing technology

Abstract It is necessary to investigate the flexural damage and evolution behavior of 3D printed continuous fiber‐reinforced composites. In this paper, acoustic emission technology (AE) is used to monitor the bending damage of 3D printed Kevlar fiber (KF) and glass fiber (GF)‐reinforced composites in real time, and gray relational analysis (GRA) and k ‐means are utilized for clustering analysis of AE signals. Subsequently, micro‐computed tomography (micro‐CT) is employed to identify the internal damage degree. For 3D printed specimens, matrix buckling and interface failure are the main failure modes, and the number of matrix and interface damage is more than that of fiber damage, and the surface of compression side (specimen's top side) is more serious than that of the back side. KF‐reinforced composites have poor delamination resistance and more serious damage than that of GF. The average maximum stress of GF and KF‐reinforced specimens is 56.37 and 42.15 MPa, and the average bending modulus is 1576.42 and 1395.36 MPa, respectively. The combination of complementary detection methods is beneficial to the nondestructive evaluation and health monitoring of 3D printed composite materials.