Multiscale investigation of the influence of geometrical imperfections, porosity, and size-dependent features on mechanical behavior of additively manufactured Ti-6Al-4V lattice struts

Abstract

Various manufacturing defects are known to have significant impact on the mechanical properties of lattice structures. Therefore, defects-embedded FE models are essential for accurate mechanical prediction. However, previous studies often focused on the investigation of complete lattice structure models. As a result, the comprehensive investigation of defects in a single strut remained elusive. The present study investigated five different defects on a single strut, namely undersizing/oversizing, diameter variation, offset of the cross section, internal voids, and local mechanical properties. It was found that the undersizing and oversizing were the primary factor affecting the discrepancy between experiments and numerical predictions for most cases. The diameter variation and offset of the cross section were seen to be dominant for small struts, especially those with 45° build orientation. Furthermore, even though the onset of localization could be observed due to the presence of voids, they had a negligible impact on elastic and initial yielding responses, partly because of their low volume fraction. Besides, the effect from geometrical inaccuracies and varied properties were mostly comparable although that of the former was more dominant in smaller samples. In addition, the sensitivity from the µCT voxel size affected both global behaviors and localization.