Structural Dynamic and Inherent Damping Characterization of Additively Manufactured Airfoil Components

Abstract

The push for low cost and higher performance/efficient turbine engines has introduced a demand for novel technologies to improve robustness to vibrations resulting in high cycle fatigue (HCF). There have been many proposed solutions to this, some passive and some active. With the advent of additive manufacturing (AM), new damping techniques can now be incorporated directly into the design and manufacture process to suppress the vibrations that cause HCF. Recent work has been investigating new ways of using AM for turbine engine applications. A specifically innovative approach using laser powder bed fusion (LPBF) is of particular note. The use of internal pockets filled with the build powder but left unfused has proved to have damping quality with >90% force response reduction. This study will investigate the as-manufactured parts, damping endurance, and structural dynamic changes when this technology is applied to a compressor-like blade. This will be done by using multiple testing methods to investigate the performance and dynamics of the blade. The study will use a computed tomography (CT) scans to investigate the pockets, structured light scans to investigate the external geometry, modal assurance criteria (MAC) to investigate the structural dynamics, and a sinusoidal strain step test to investigate endurance. This study found similar endurance and damping capabilities as previously observed, in addition to finding that the inclusion of the unfused powder pockets did not affect mode shapes measured by the MAC.