With the advent of novel Additive Manufacturing (AM) techniques, it becomes crucial to properly address the issues related to the printing processes in the mechanical response of the printed outcomes.Among different metal-based AM processes, Wire-and-Arc Additive Manufacturing (WAAM) results to be the most suitable to realize large structural components and real-scale structures, with ideally almost no geometrical constraints in terms of shape and size.
However, some non-negligible issues related to the printing process should be properly addressed in structural design phase: (i) different material properties with respects to the wrought material; (ii) anisotropic behavior of the printed part; (iii) geometrical irregularities related to the WAAM process.
In order to overcome the above-mentioned issues, the research group from University of Bologna has adapted the conventional design approach for traditionally-manufactured stainless steel structures to those realized with WAAM. Experimental and numerical studies have been carried out on WAAM-304L stainless steel elements, to accurately evaluate the key material properties of the base material and possible influences of the geometrical irregularities for as-built pieces. The marked anisotropy of the mechanical response of WAAM-produced stainless steel was also confirmed by microstructural investigations.
The experimental results were used to calibrate design values and partial safety factors through the procedure explained in Annex D of Eurocode 0 (design assisted by testing) for new structural materials. Additional considerations were also drawn for Young’s modulus, traditionally considered as a deterministic value[7]. The calibration results were in good agreement with the values suggested for stainless steel structures as in EC3. The long-term objectiveof this researchis to provide a contribution to deliver ad-hoc guidelines for the structural design of structures realized with WAAM-produced steel members.
References
Laghi, V., Palermo, M., Gasparini, G., Veljkovic, M., & Trombetti, T. (2020). Assessment of design mechanical parameters and partial safety factors for Wire-and-Arc Additive Manufactured stainless steel. Engineering Structures, 225, 111314.