Numerical Investigation on Mode I and Mode <scp>II</scp> Fracture in Additively Manufactured <scp>PLA</scp> Material Using <scp>XFEM</scp>

ABSTRACT This study aims to numerically investigate the Mode I and Mode II fracture behaviors of additively manufactured, degradable, bioplastic Polylactic acid (PLA). Numerical simulations for both fracture modes were performed using the eXtended finite element method (XFEM), incorporating the mechanical and fracture material properties of PLA extracted from specimens fabricated in three different build orientations (i.e., horizontal, lateral, and vertical). The maximum principal stress and fracture energy power‐law criteria were respectively utilized to model damage initiation and evolution in two‐dimensional (2D) and three‐dimensional (3D) analyses. Experimental load–displacement responses of single‐edge notched bending specimens obtained from symmetric and asymmetric four‐point bending tests were utilized to validate the Mode I and Mode II XFEM analyses, respectively. A transversely isotropic elasticity model was employed to account for the effects of build orientation. A common calibration factor was applied to the fracture and mechanical properties to ensure agreement between the numerical and experimental results. It was found that both 2D and 3D analyses are of high accuracy compared to the corresponding experimental results, with differences of 2.7%, 8%, 4.5%, and 3.6% observed for the 2D and 3D analyses of Mode I and Mode II fracture loads, respectively.