Assessing Manufacturing Repeatability of Inherently Damped Nickel Alloy Components via Forced-Response Testing

The ability to repeat an additive manufacturing (AM) process that fabricates a unique specimen with inherent damping capability is explored. Using the Laser Powder Bed Fusion (LPBF) AM process, four Inconel 718 components with the same internal and external geometries are manufactured. The damping performance of the four specimens are determined to make comparisons against each other, previously studied inherently damped specimens, and fully-fused components of the same material and external geometry. Results of the study demonstrate similarities in the damping performance of each beam despite the specimens being made with three different fabrication parameters, two different LPBF scan strategies, and two different build sequences. Moreover, the measured inherent damping in the four beams is significantly higher (9–16 times) compared to the damping of a fully-fused beam. The results of the inherently damped beams in this study is also compared to previous specimens of different geometries using a shear-displacement criterion that determines the effectiveness of damping. The results show an 85% correlation between damping performance and calculated shear-displacement value. Therefore, despite three sets of fabrication parameters, two scan strategies, and two build sequences for the same geometry/dimensioned specimen, the results firmly demonstrate inherent damping repeatability is strongly driven by the unique geometry of the component, which ensures repeatability with minimal sensitivity in the manufacturing process.