Mixed-mode tensile/shear fracture of the additively manufactured components under dynamic and static loads

Abstract

In the practical implementation of the Additively Manufactured (AM) construction in engineering designs, Fused Deposition Modeling (FDM) is recently used to manufacture the inexpensive Acrylonitrile Butadiene Styrene (ABS) parts. The cracking behaviors of such layered components are inspected using the Semi-Circular Bending (SCB) fracture samples. In particular, the effect of anisotropy or layered nature of 3D printed specimens is only considered on the fracture manner among the affecting parameters. The dynamic and static three-point bend tests are conducted from pure mode I to pure mode II conditions. Dynamic experiments are performed using a modified Charpy instrument, and the required energies for the crack initiation are obtained. In the next step, a finite element model based on the Equivalent Material Concept-Generalized Maximum Tangential Stress (EMC-GMTS) failure theory is introduced, and its predictions are compared with the obtained experimental data. Under different loading rates, the crack path trajectories and fracture behavior is surveyed in detail concerning the isotropic counterparts in two micro and macro scales. According to the SEM images and the validity of the brittle fracture theory (with a maximum of 5% error), it is proved that the SCB samples made from ABS are fractured in a brittle manner. The fracture behavior of the FDM 3D-printed structures under dynamic loading conditions is analogous to those homogenous materials, especially where the mode I deformation is dominant. Also, the dynamic and static paths for dominantly pure mode II loading conditions are nearly identical.