<p>One major benefit of Additive Manufacturing is parts counts reduction. Several formerly distinct parts can be printed as one unit, reducing cost and weight. However, the interface between parts is often a major source of vibration damping, so eliminating interfaces can lead to high cycle fatigue failures. To alleviate this, several researchers have been exploring the integration of damping features inside parts. Leaving a small pocket of unfused powder creates a particle damper. Particle dampers have long been known to suppress unwanted vibration. However they are highly complex and predicting their behavior is difficult. The particle damper literature often has contradictory claims, as what works best for one application does not work for another. Because the additive feedstock powder is much smaller (~25 um) than particles in typical particle dampers, it is difficult to draw conclusions from the existing literature to develop design guidelines. This papers reports on a Discrete Element Method (DEM) numerical simulation of additively manufactured cantilever beams with a small pocket of unfused powder. DEM explicitly simulates the motion of each particle and their interactions. Previously reported experiments with varying beam geometry showed nearly an order of magnitude difference in damping ratio depending on the location of the pocket along the beam. The simulation was able to accurately predict the damping ratio based on the input geometry. Particle-wall momentum exchange, particle-particle friction, and particle-particle inelastic collisions were all shown to be contributors to the damping ratio. This correlated simulation tool can be used to optimize future designs.</p>

Discrete Element Method Simulations of Additively Manufactured Components With Integrated Particle Dampers

Paper Proceedings: https://asmedigitalcollection.asme.org/GT/GT2021/volume/84898

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