Research Summary Report of A06
Laser Powder-Bed Fusion (LPBF) of Steel Elements for Construction – Basics of Design and Mechanical Resilience.
[12.05.2023]
Diller, Johannes; Doctoral researcher; johannes.diller@tum.de,
Siebert, Dorina; Doctoral researcher; dorina.siebert@tum.de
Technical University of Munich, Chair of Metal Structures
Wenzler, David; Doctoral researcher; david.wenzler@tum.de
Technical University of Munich, Institute for Machine Tools and Industrial Management
Summary
The project A06 aims to explore and evaluate the factors influencing the manufacturing of safe and durable structural steel elements by Powder Bed Fusion of Metals using a Laser Beam (PBF-LB/M). Thereby, the PBF-LB/M process, the post-treatment, and the geometrical aspects in terms of microstructure and mechanical properties were investigated and correlations determined. In the first funding period, it is focused on analyzing small-scale specimens and complex facade elements with multiaxial stress states. Based on the results, a first methodology for a qualified Additive Manufacturing (AM) design of safe and durable structural steel elements will be derived.
Current state of research
The development of additive manufacturing enables the creation of new, complex, and application-specific designs. With additive manufacturing, it is possible to create lattice structures for the damping of cyclic loads. Lattice structures should exhibit pronounced deformation behaviour and thus dissipate more energy than solid material. They are complex – not only in fabrication but also in design. A parameter study was performed for unit cells as well as lattice structures with BCC (Body-centered cubic), BCCZ, FCC (Face-centered cubic), FCCZ, FBCC, and FBCCZ topologies. The above topologies were investigated with respect to the deformation behaviour as well as the energy dissipation capacity and compared with each other. The chosen parameters were the relative density and the cell size. The parameter study revealed that the energy dissipation can be maximized by applying a constant structural deformation. The structures with a large relative density are stiff and deform less. In contrast, structures with a low relative density exhibit severe softening and fail under even small actions. It was further shown that the elastic support force of the lattice structures is greater than that of the unit cell. Thus, the investigation has shown that the FCCZ topology has sufficient stiffness and thus has the maximum energy absorption.
Fig 1: FBBC (left) and FBCCZ (right) unit cells (top) and their deformation behaviour at 68% strain.
Deformation behaviour of body-centered cubic lattice structure.
