Development, numerical simulation and experimental characterization of selective laser melting (SLM) microstructures with deliberately introduced dissipation

• Applicants: Professor Dr.-Ing. Wolfgang A. Wall; Professor Dr.-Ing. Michael Friedrich Zäh
• Subject Area: Primary Shaping and Reshaping Technology, Additive Manufacturing ; Mechanics
• Term: from 2019 to 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 414180263

Due to novel materials and innovative manufacturing technologies, the concept of lightweight design has become more and more prevalent within the last years. Unfortunately, the resulting technical components are often more sensitive to undesired vibrations. The aim of this proposal is to address these unwanted effects directly at their source by employing novel manufacturing technologies for the development of multi-functional microstructures that combine lightweight design with effective and controllable dissipation characteristics in an integral and multi-functional way. Concretely, we exploit the advantages of selective laser melting (SLM), a recent and very promising representative of powder-fusion-based additive manufacturing (AM) processes, in order to generate the intended microstructures. Due to the layer-wise production, the SLM process is capable of producing highly complex geometries that cannot be obtained by conventional manufacturing processes. This paradigm shift in mechanical design has already enabled the manufacturing of novel microstructures typically optimized in terms of weight and stiffness. In order to combine these lightweight designs with the desired damping characteristics, four fundamental microstructural concepts based on different physical dissipation phenomena such as micro-tribology, solid material damping and viscous damping in fluids are proposed: a microstructure consisting of loose metal powder (that is already provided by the SLM process), a porous microstructure filled with highly viscous oil, a lightweight metal lattice structure filled with solidified polymer resin, and finally an intelligent microstructure consisting of internal micro-friction elements that allow for damping of individual deformation modes. In order to investigate and implement the proposed concepts, the competences of the two participating institutions in terms of experimental and manufacturing expertise on the one hand and modeling and simulation related know-how on the other hand are combined in an optimal way. Accurate mechanical microscale models will be developed in order to investigate the underlying physical dissipation phenomena. Subsequently, these microscale models will be transferred into homogenized macroscale models, thus generating predictive simulation tools that allow for an efficient evaluation and optimization of the proposed damping concepts for practically relevant design parts. Detailed experimental investigations on custom-built samples will serve for an in-depth microstructure characterization, model parameter determination and eventually for verification of the derived models and validation of the proposed dissipation concepts. Based on the most promising concepts, a prototype in form of a cutting tool will be manufactured in order to assess the achievable damping characteristics also in a practically relevant environment.

• DFG Programme: Research Grants
• Co-Investigator: Dr.-Ing. Christoph Meier