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Nature has evolved structural materials along millions of years of incremental changes to fulfil functional requirements of very different situations. Let´s take as an example the sharks, one of the best adapted species for swimming across the oceans, and their smooth skin that is composed of millions of small scales (denticles), with complex geometries formed by sharp spines and micro-grooves aligned with flow direction, varying in size and shape at different locations of the sharkskin. The purpose of this microstructure is to reduce the viscous drag produced by the water when it adheres to the hull forming the fluid boundary layer, which can stick out the added mass to the weight of the fish and increase dramatically its peak speed. Inspired by this natural solution, we have started the design of a bioinspired new material, to be incorporated to the hull wet surface, reducing the viscous drag and increasing the velocity and the efficiency (less fuel consumption) of the ship. In this way, it will be easier to control the green effect gas emissions while sailing. We present the development of this new bioinspired, hybrid material with scales obtained by additive manufacturing using polymeric materials. To control the orientation of the denticles respect to flow direction, the scales have been mounted on a substrate of hydrogel, who interact with the fluid field of pressures to adapt the angle of the moving scales as the velocity increases. No mechanical devices are needed, as the hydrogel act as a nonlinear spring accommodating the movements of the scales. CFD code helps in the development of the most efficient shape and coating design. A water channel has been developed to measure the actual forces acting on the surface of coated panels.

Abstract

The present work addresses different aspects of the manufacturing process optimization of structural components for the automotive sector. More precisley the development of a novel bumper beam is being pursued by combining steel and composite to achieve, ultimatly, a weight reduction of the current component. For this it has been fundamental to consider not only the requirements of the part, specially from the safety prespective, but also manufacturing criteria.

The study carried out has included everything from the design of the component up to the evaluation of a wide range of composite materials, both of thermostable and thermoplastic nature. Thus, different manufacturing technologies together with their process window and tooling desing has been accomplished in this work. In addition, several surface treatment technologies including cutting-edge ones such as laser texturing, have been combined with different strategies to ensure, in this way, the optimal performance of the solution.

Finally, the development of ad-hoc demonstrators has allowed identifying the most suitable design and materials. Also, it has been possible to quantify the performance of the components, process times and final cost. Finally, a 25% weight reduction has been achieved, maintaining the mechanical properties and cycle times down to 5 minutes.

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