New composite process minimizes boat-slamming hull damage
Wave-slapping, high-speed rides in your powerboat may be fun, but they sure can take a toll on the boat's structure. Researchers in Spain have developed a new technology -- based on composite materials and viscoelastic layers -- that improves the hull resistance on speedboats and similar watercraft.
The new manufacturing system, developed by scientists at the Universidad Politécnica de Madrid's (UPM) School of Naval Architecture and Marine Engineering, inserts a thin viscoelastic layer among the layers of composite materials that build the hull. The inserted material absorbs and fades the energy caused by impacts with the water surface.
Their tests show that the frequency of repair of damaged hulls when using this new system can be three times less. The system not only extends the useful life of the high-speed craft, but it also can increase the safety of the people on board.
Developing the system
The cyclic slamming can provoke significant vessel damage, especially when the boats are made of composite materials such as inorganic fibers (glass, carbon) and agglomerate polymers (polyester, vinyl ester, or epoxy). These composite materials are light but are also more sensitive to impacts than metallic materials (steel, aluminum).
Viscoelastic layer of protection developed with additive manufacturing technology. (Note how you can see the rubber material embedded into the fiber-laying process.)[Credit: Patrick Townsend Valencia]
During the short period of time between the start of the impact and the separation of water around the vessel, the strain supported by the material grows rapidly and the deformation speeds imposed are very high. Under these conditions, the material can develop internal micro-tears.
The newly developed incorporated layer is made of regular hexagons of a rigid polymer that encapsulates a light and viscoelastic material made of a rubber, which was specially designed for this system. The energy of the wave slam is captured by the viscoelastic layer, which is deformed by temporarily storing the energy and protecting the hull. After the impact, the viscoelastic layer gives the stored energy back to the sea. Results show that the damage caused is drastically reduced because the viscoelastic layer protects the inner material.
Of particular note is the construction using the new material. This protection is not added to the craft structure, like an independent layer placed in the bottom of the hull. Instead, the material is embedded in the fiber layers during construction, which provides more effective and durable protection against impacts.
"By using this new manufacturing technology, the resistance of high-speed crafts are protected even in the hardest conditions of navigation, extending its useful life and improving the safety of the people on board," says Juan Carlos Suárez Bermejo, UPM's head researcher on the project.
Shipyards, boat owners, and ship classification societies are already showing interest in the gradual introduction of these new developments in the field of boatmaking and shipbuilding.
Want more details? See the paper "Reduction of slamming damage in the hull of high-speed crafts manufactured from composite materials using viscoelastic layers" in the July 2018 issue of Ocean Engineering (paper PDF purchase required).
Source: Universidad Politécnica de Madrid
Published November 2018
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