Design, fabrication and mechanical characterization studies on Wire and Arc Additively Manufactured (WAAM) diagrid elements

The design approach changed in the last decades with the innovation offered by software for Computer-Aided Design (CAD), three-dimensional computer modelling and digital fabrication methods enabling new forms. The development in digital fabrication techniques led to the application of automatic processes in the structural engineering sector through Additive Manufacturing (AM) based technologies. It offers numerous benefits over conventional manufacturing methods, such as design of more complex and optimized components due to greater freedoms in shape and geometry, therefore bringing to a reduced material usage and shortened build times. The focus of this research is on the metal additive manufacturing methods, in particular, the adopted technique is the Wire-and-Arc Additive Manufacturing (WAAM), which best suits the possibility to realize large-scale metal structures and to allow new geometric forms. WAAM advantages compared to the other processes are fast large-scale production, freedoms in shape and geometry, structural efficiency with reduced material usage. The current research comprises the overarching process from the computational design to the mechanical characterization of the WAAM-produced elements, through the fabrication step. The computational design and fabrication stages were carried out at Technische Universität Braunschweig. There is still limited research focused on the characterization of WAAM-produced metal elements for structural engineering applications, therefore the research carried out at University of Bologna was focused on the establishment of 3D-outcome mechanical properties, pointing up the influence of surface roughness and imperfections on the mechanical response, together with the study on how the intersection between WAAM-produced bars influences the overall behavior of the specimen.