Structural behaviour of point-by-point wire arc additively manufactured steel bars under compressive loading

Wire arc additive manufacturing combined with optimization tools for computational design shows a big potential with respect to the current efforts in the architecture, engineering, and construction industry of reducing the consumption of materials by using them more efficiently. These technologies allow to design and fabricate steel components, connections, and structures with material deposited only were structurally necessary. The findings presented in this paper focus on wire arc additively manufactured bars, robotically printed by point-by-point deposition and subjected to compressive loading. Such elements can be used for realizing stand-alone components or connections between existing parts, either alone or in combination with continuous deposition, and are generally susceptible to flexural buckling due to their slenderness. The influence on the flexural buckling behaviour of aspects like printing directions, slenderness, and support conditions was investigated by experiments and finite element simulations. In addition, the irregular geometry of the wire arc additively manufactured bars was evaluated based on three-dimensional scans, the identified characteristics were correlated with the flexural buckling results, and the relevance of the irregular surface geometry in predictive buckling simulations was assessed. The experiments showed consistent results indicating that such bars could be produced in a reliable and repeatable manner. The conducted simulations with the scanned geometry and an elastic-plastic material model allowed for an overall satisfactory prediction of the flexural buckling resistance. With regard to future design approaches, it was shown that the existing buckling curve for solid sections is suitable for point-by-point wire arc additively manufactured nearly straight bars and simulations with a constant equivalent diameter can be used for predicting the flexural buckling resistance if a rather low equivalent geometric imperfection is assumed.