Mode selective damping behavior of additively manufactured beam structures

Abstract Additive manufacturing, with its inherent process-related degrees of freedom, offers significant potential for manufacturing high-performance parts. This allows effects to be integrated that enable completely new solution mechanisms for existing conflicting objectives, which means that the degrees of design freedom make it possible to optimize the application-specific behavior of a part. In addition to the thermal or electrical properties, the dynamic behavior of a part can also be optimized, for example. This article focuses on the integration of the particle damping effect, which can contribute significantly to increased part damping. Unfused powder inside the part leads to energy dissipation through impact and friction mechanisms. However, the particle damping effect is not yet fully explored, lacking essential knowledge for application in product design. Therefore, test specimens with particle dampers, manufactured using laser powder bed fusion by laser beam from 1.2709 tool steel, are investigated, with variations in the position and size of the particle-filled cavities. To determine damping, the samples are freely supported and excited with an impulse. The damping ratio is calculated based on the recorded decay behavior. The results show an increase in damping ratio of up to a factor of 70, with the extent of improvement strongly dependent on the cavity’s volume and, crucially, its position relative to the part’s mode shape. A linear relationship between the damping ratio and the displacement of the volume of the cavities of the beams is shown.