Testing, simulation and optimisation of additively manufactured structural hollow sections

Additive manufacturing (AM) is gaining increasing prominence in the construction industry, offering the potential for enhanced design freedom and reduced material use. However, the performance of additively manufactured metallic structural elements and the possible benefits associated with the attainable optimised geometries have seldom been investigated. The primary aim of this study is therefore to conduct an experimental and numerical investigation of additively manufactured metallic components, considering material behaviour, welded components and optimised tubular profiles. An experimental investigation was first conducted to examine the microstructural and mechanical properties of AM materials. Two grades of powder bed fusion (PBF) stainless steel (316L and CX) were considered, and the weldability and joining characteristics of PBF 316L stainless steel were also examined. The underlying microstructures were characterised and correlated with the measured mechanical properties from tensile coupon tests. At the cross-sectional level, axial compression tests were carried out on PBF circular hollow sections; advanced measuring techniques, including 3D laser-scanning and digital image correlation, were employed in the tests. Finite element (FE) models were developed to replicate the test results and to generate supplementary cross-sectional resistance data. Comparisons between design predictions and the test and FE data were made to evaluate the applicability of the existing codified design rules to additively manufactured cross-sections. In order to increase the axial compressive resistance and to reduce the imperfection sensitivity of very slender circular cross-sections (or cylindrical shells), optimised corrugated shells were sought through the use of the Particle Swarm Optimisation algorithm in conjunction with cross-section profile generation and numerical analyses. An experimental investigation into the cross-sectional behaviour of the resulting optimised shells, additively manufactured by PBF in 316L and CX stainless steels, was undertaken. The test results verified that the corrugated cylindrical shells achieved significantly higher capacities than their circular counterparts and with reduced imperfection sensitivity.Open Acces