Experimental analysis of additive-manufactured particle damping structures in vibration-sensitive optical systems

High-precision optical systems, such as star trackers, are highly sensitive to vibration loads during launch and in orbit, both of which can cause structural damage and imaging instability. This study evaluates additively manufactured particle-damped (AMPD) structures-realized by leaving unmelted powder cavities in powder bed fusion with a laser beam for metals (PBF-LB/M) builds-to mitigate these effects. Five variants of optical post and mirror-mount assemblies, manufactured from 316L stainless steel, feature overall cavity volumes ranging from 11.6 % to 30.9 % of the original full-sintered reference assembly. A 50-1250 Hz linear sweep is applied with a synchonized test rig via a modal shaker, while a high-speed camera tracked laser-spot deviations and accelerometers recorded structural responses. Frequency response functions obtained by Welch's method and complex-plane circle fitting yielded effective modal-mass increases of up to 17.9 times. Compared to the reference assembly, AMPD designs reduced peak optical spot deviation by up to 66.9 % in the 670-850 Hz band. It is worth mentioning that none of the tested configurations performed best in every frequency interval. Instead, the advantages of each design changed depending on the frequency range and the particular setup. This means that selecting or optimizing AMPD structures should always take the specific conditions and requirements into account, rather than relying on a one-size-fits-all solution.