Numerical assessment of the effects of microcrack interaction in AM components

Abstract

A combined analytical–numerical method to study the effects of linear microcracks and their interaction in additively manufactured components is presented. The 2-D method combines an analytical technique to solve the interaction of microcracks and a numerical RVE type technique to represent the microcracking within a finite element framework using Abaqus finite element software. The method is applied to both a unit cell and test specimen type geometries containing defect patterns generated based on general trends reported for AM materials. The approach is able to determine the local stress intensity factors for each microcrack and their stiffness degradation effects in the continuum. Parallel defect patterns, such as co-oriented lack-of-fusion defects between build layers in AM materials, induce the greatest interaction effects while overall interaction effects in random patterns tend to cancel out. Stacked surface defects produce shielding effects on each other, which may cause a neighbouring subsurface defect to be more critical than the surface defects. The results show that the common geometrical interacting defect re-characterisation rules may provide an incorrect prediction of the failure origin. Finally, the applicability of the method is demonstrated with an example AM component.