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Additive Manufacturing Application to a Ship Propeller Model for Experimental Activity in the Cavitation Tunnel

Additive manufacturing (AM), or three dimensional printing, is a modern way to build objects with possibly a high degree of accuracy and favorable cost/benefit ratio. This approach is widely used by many manufacturing industries and a certain interest for this innovative production technology is also growing in the ship design and production field. To this regard, the experimental activity at the model scale is often necessary for the ship performance assessment in the design phase. In the article, preliminary results of a propeller model for the cavitation tunnel, built with additive technology, are presented, showing the strengths and weaknesses of the printed model. Moreover, as an introductive overview, different AM technologies are briefly described, with the aim to point out potential applicability to ships.
 
 
 Additive Manufacturing (AM), also known as 3D printing, is a well-known process to shape objects by layering materials under numerical control until the completion of the work. It represents an innovative approach because it is based on the addition of material instead of carving material from a block (like CNC—Computer Numerical Control, i.e. a manufacturing approach relying on mills, drills, and other numerically controlled tools). AM is deemed as an outstanding flywheel for innovation in the productive world, and the shipbuilding industry seems to have started realizing the advantages of this technology, already largely used, e.g., in the automotive, aerospace, biomedical, and energy industries (Shahi 2016; Satish Prakasha et al. 2018).
 In this perspective, an introductive overview of different AM typologies is presented in the article, to possibly understand how it could be used to improve ship design and production. The overview includes the applicable technologies, focusing on the printing process, the materials, and the mechanical properties of the final printed object. A practical example of AM technology application is presented regarding the printing of the blades of a ship's propeller model for experiments in a cavitation tunnel.
