Mechanical and microstructural features of Wire Arc Additively Manufactured steel tubular sandwich structural members

Innovations and advancements in the field of robotics have led to the exploration of new manufacturing techniques applicable across various industries. Advancements in both Computer-Aided Design (CAD) software and the adoption of Additive Manufacturing (AM) processes have enabled the fabrication of complex geometries. While AM has found applications that are well-established in sectors such as aerospace and medicine, its adoption in the construction industry remains pioneering. Among the various AM processes, Wire-and-Arc Additive Manufacturing (WAAM) technology offers greater design freedom and the ability to fabricate complex steel elements with varying shapes and sizes. These capabilities make WAAM technology suitable for the Architecture, Engineering, and Construction (AEC) sector, where large-scale structural elements are often required. The adoption of WAAM technology necessitates detailed knowledge of the material and structural behavior of WAAM-produced steel elements for designing structural components. Accordingly, this study focuses on initial investigations into the geometry, porosity, and mechanical behavior of a novel cross-sectional shape suitable for tree-like structural members in large pavilions or infrastructure projects. This novel cross-section is hereafter referred to as the Tubular Sandwich Section (TSS). The study begins with the conceptual design phase and WAAM fabrication of initial TSS prototypes. Subsequently, the objective shifts to the geometrical and mechanical characterization of the TSS prototypes fabricated using WAAM technology. In particular Tomography test results revealed the influence of WAAM deposition strategies on porosity location and dimensions. Tensile mechanical tests, conducted on both as-built and machined dog bones extracted from one of the prototypes, demonstrated that WAAM material behavior is influenced by the geometrical features.