3D‐Printing with Steel ‐ Additive Manufacturing Connections and Structures

Abstract

Automated production is finding its way into fabrication of structural steel. One robot holds attachments (stiffeners, head plates, etc.) to a steel beam or column and another robot produces weld seams. However, welding robots can also be used for additive manufacturing (Wire + Arc Additive Manufacturing, WAAM). The wire electrode serves as printing material. The Institute for Steel Construction and Materials Mechanics in Darmstadt is investigating how typical connecting elements of steel construction can be printed directly on steel beams using Additive Manufacturing with arc welding and robots. Furthermore structural elements like nodal points are printed and even complete structures like columns and a little bridge have been manufactured additively already. The main focus is on determining suitable welding and process parameters. In addition, topology optimization is used to find good structures using a low amount of material. This is possible due to the free design prospects of 3D‐printing. This opens for novel design and production strategies.

Additive Manufacturing in Off-Site Construction: Review and Future Directions

“…A particular DED process that draws attention for construction applications is the Wire + Arc Additive Manufacturing (WAAM) technology, which utilizes heat from an electric arc to melt a welding metal wire feedstock on a motion assembly without theoretical dimensional limitations [ 54 ] To maximize the fabrication freedom inherent in AM, topology optimization of structural elements was explored for mild steel components fabricated using Wire Arc Additive Manufacturing (WAAM) [ 67 , 68 ]. Lightweight construction and efficient material utilization are achieved while maintaining the load-bearing capacity and rigidity of the overall structure.…”

“…The optimization of a bolted flag plate replaced with a directly printable hook to distribute the stresses on a beam and column connection is presented in Figure 6 a,b [ 67 ]. A customized node that can connect four steel beams, girders, or columns with symmetric loading is also shown in Figure 6 c,d [ 68 ]. Other structural elements explored include I-section stiffeners that prevent the bending of a flange, clamps for braces that are erected at an angle, and T-stub end plates with a bolted connection.…”

“…Other structural elements explored include I-section stiffeners that prevent the bending of a flange, clamps for braces that are erected at an angle, and T-stub end plates with a bolted connection. To demonstrate the topologically optimized components, on-site construction of a bridge was presented in Darmstadt [ 68 ]. Tensile tests show that the yield strength and tensile strength values were slightly below the material specifications for the mild steel filler wire used.…”

Generative Design and Integrated 3D Printing Manufacture of Cross Joints

“…Meanwhile, a large number of manual operations lead to huge labor consumption, especially when the types and numbers of joints in an entire structure are substantial, as shown in Figure 1 b. 3D printing is a transformative advanced digital manufacturing technology, developed in the past 30 years [ 24 , 25 , 26 ]. Differently from traditional fabrication methods (cutting, grinding, casting, forging, etc.…”

Evaluation of material properties of 3D printed carbon steel for material modelling

“…The tensile properties obtained with the samples tested in the transition zone exceed the minimum tensile strength requirements of forged materials. Lange et al [10,11] redesigned and printed some traditional steel components incorporating the advantages of WAAM and achieved valuable material-savings. Haden et al [12] investigated the mechanical properties of WAAM steel made of stainless steel 304 and mild steel ER70S respectively.…”