DMEC researchers have developed innovative solutions for the production of aluminum alloy components with biomimetic surfaces inspired by sea bass scales. The Levrek project (sea bass in Turkish) aims to recreate the sea bass scales on the bulb of the rudder of the Polimi Sailing Team sailboat.
The Levrek project looks to improve the structural characteristics of the component, reducing its weight by using additive manufacturing techniques and, at the same time, improving its fluid dynamic characteristics by working on the texture of its surface. Researchers modeled the natural characteristics of the fish in a digital environment, conducted parametric analyses using a Computational Fluid Dynamics (CFD) approach to evaluate their performance, and choose the most efficient proportions of the fish scales
After undergoing topology optimization, the metallic scales were produced by laser powder bed fusion (L-PBF) and applied to a rudder bulb. This research fits perfectly into 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 made up of sailing, CFD, and AM experts. Alessandro Scarpellini, the leader of the Polimi Sailing Team worked together with Dr. Paolo Schito and Prof. Ali Gökhan Demir. For the innovative design, a first study was conducted on the hydrodynamics of the sea bass scales, identifying the optimal size of the scale in order to reduce the fluid dynamic resistance of the rudder bulb.
First, the researchers modeled the fish scales in a CAD environment: this made it possible to identify different scale sizes to be tested in the CFD environment using the OpenFOAM open-source framework on the CFDHub High-Performance Computer (HPC) infrastructure.
In addition to identifying the ideal dimensions, the researchers determined the influence of the surface roughness and the speed of the boat. Subsequently, they focused on building the component: the chosen AM process was SLM and the material used was the AlSi7Mg0.6 alloy. The rudder bulb was then topologically optimized to reduce component weight. The fish scale chosen has been integrated into the surface of the bulb. The component was manufactured using a Trumpf TruPrint 3000 printer at AddMe.Lab. The result is a first-of-its-kind rudder bulb – a topologically optimized metal component that incorporates bio-inspired surfaces.
The results of this research may pave the way for new naval applications to improve the performance of vessels at sea and at the same time lighten their components. After careful review, they were published in a scientific journal. Thanks to its innovativeness, the work carried out was also appreciated by the world of the industry which decided to reward Alessandro Scarpellini: the young team leader won the UCIMU Thesis Award from the Italian Manufacturers of Machine Tools, Robots, Automation Systems, and Auxiliary Products.