Non-destructive defect detection of LPBF-manufactured A205 aluminium alloy lattice structures

Abstract

Engineering and design have been altered significantly by the production of metal lattice structures (MLS) utilizing additive manufacturing (AM), particularly laser powder bed fusion (LPBF). LPBF allows to produce such complex three-dimensional structures with a degree of complexity and accuracy which is not possible by conventional manufacturing, in particular regarding periodically repeated unit cells. However, despite its advantages, LPBF can cause defects, e.g. small internal porosities which in this case preferably can be observed with non-destructive inspection (NDI). Therefore, this study aims to validate the detectability of LPBF imperfections by exploring the impulse excitation technique (IET) as an NDI method for MLS and bulk samples produced by LPBF in the high-strength aluminium alloy A205 and including on-purpose manufactured defects. As a result of the measurements, the detection of selectively placed internal defects was successfully determined according to the differences in the resonant frequencies of defect-free and defected samples.