Meccanica Magazine n. 4

meccanica magazine
38
ENG
Between nature and engineering: Additive manufacturing enables
efficient components for nautical applications
DMEC researchers developed a novel solution for producing
biomimetic surface textures - inspired by the European bass - on Alalloy
components. Project Levrek (Levrek is the Turkish name of the
European Bass) aims to mimic the scales of the European bass on a
rudder bulb designed for the sailing boat for the Polimi Sailing Team.
The objective of the project is to improve the structural features of
the component, reducing its weight using additive manufacturing
(AM) technique, taking the chance also to improve the fluid-dynamic
features by texturing its surface.
The researchers modelled the natural features of the fish in a digital
environment, carried out a parametric analysis with computational
fluid dynamics (CFD) approach to assess its performance and
choose the most efficient scale proportions.
After undergoing a topology optimization phase and being produced
by laser powder bed fusion, a layer-by-layer additive manufacturing
(AM) technique, the designed metallic scales were applied on a rudder
bulb. These research activities perfectly meets the objectives of the
Departments of Excellence in the LIS4.0 project, where the focus is
on Lightweight and Smart structures.
The research required a multidisciplinary team composed by
Sailing, CFD and AM experts. Alessandro Scarpellini, the leader of
Polimi Sailing Team worked together with Dr. Paolo Schito and Prof.
Ali Gökhan Demir. For the innovative design, a first study on the
hydrodynamics of European Bass scales was conducted, identifying
the most promising scale dimension that reduces the rudder bulb
fluid-dynamic resistance. The researchers modelled the fish scales
in a 3D computer aided design environment first.
Different scale dimensions were tested using CFD within the
opensource framework OpenFOAM on the High-Performance
Computer (HPC) infrastructure CFDHub: the researchers discovered
the most suitable dimensions as well as the influence of surface
roughness and the sail speed. Then the focus was on the realization
of the component: laser powder bed fusion was chosen as metal
additive manufacturing process and the material is AlSi7Mg0.6 alloy.
The rudder bulb was then topologically optimized to reduce the
weight of the component. The chosen fish scale was integrated to
the surface of the bulb. Finally, the component was produced by a
Trumpf TruPrint 3000 at AddMe.Lab. The produced rudder bulb is
one of the first of its kind incorporating bioinspired surfaces and
topological optimization in a metallic component.
For the naval applications, the novel findings can open new
possibilities for improving the sailing performance, but also for
reducing material usage. The initial findings of the research has
been peer-reviewed and published. The innovativeness of the work
has also been appreciated by the industry as Alessandro Scarpellini
was awarded the UCIMU Thesis Prize by the Italian Machine Tool,
Robots, Automation Systems and Ancillary Products Manufacturers’
Association.