Wire arc additively manufactured aluminium alloy open sections: 3D geometric analysis and compressive behaviour

Wire arc additive manufacturing (WAAM) is sparking extensive research interests in recent years, as the technique offers an efficient pathway fabricating metallic structural components with complex geometries. However, the limited insights into the structural performance of WAAM metallic members hinder their practical application in construction. As part of an ongoing research project on WAAM metallic members, this paper presents an experimental study on the geometric features and cross-section compressive behaviour of WAAM aluminium alloy open section stub columns. Fifteen stub column specimens with angle, channel and π-shaped section profiles were firstly printed using ER5356 aluminium alloy feedstock wires and tested under compression to study their local buckling behaviour. Before testing, the geometric properties and geometric imperfections (including initial local geometric imperfections and cross-section out-of-squareness) of the specimens were inspected using a 3D laser scanner. The measured initial local geometric imperfections and out-of-squareness of each specimen were analysed. The results from stub column tests were subsequently used to assess the applicability of cross-section classifications and predicted resistances from existing design methods (for conventionally fabricated aluminium alloy members), including the European, American and Australian/New Zealand codes, together with the continuous strength method (CSM). The assessment results generally revealed that (i) the three sets of codified slenderness limits provided safe cross-section classification, with more accurate classification offered by the American specification and Australian/New Zealand standard and (ii) the three design codes provided safe compression resistance predictions (though conservative to different extents, especially for the stocky cross-sections), while the Annex H of the European code and the CSM provided more accurate and consistent resistance predictions due to their proper consideration of material strain hardening.