What do PU/carbon spars and the Valencia lighthouse have in common?

Saertex reinforcements, infusion, speed of fabrication and long life.

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Saertex reinforcements, infusion, speed of fabrication and long life.

I recently ran across two very different videos focused on composites that showcased new directions in manufacturing. The first is from Covestro (Leverkusen, Germany), formerly Bayer MaterialScience, and centers around a project it conducted with reinforcements supplier Saertex (Saerbeck, Germany), machine supplier Huebers (Bocholt, Germany) and the German Aerospace Center (DLR) in Stade, to demonstrate the infusion of a 45m long spar cap for a wind blade using polyurethane resin.

The idea behind the project is to look at the faster resin flow and improved fatigue life benefits of polyurethane vs. the normal epoxy, vinylester and polyester resins used to infuse wind blades. Both process speed and fatigue are seen as important improvements as blades get longer and their manufacturing and technical performance requirements change. Covestro also cites potential cost benefits.

According to an article published by A.P. Vassilopoulos, from the École Polytechnique Fédérale de Lausanne  (EFPL, Lausanne, Switzerland), wind blades must withstand significant fatigue loads, estimated to total 109 cycles during a 25-year service life. In comparison, a short-span vehicular bridge can see 107 to 108 fatigue cycles over a 50-70 year span. As blades have increased in length from 45m to 65m and now 84m, with a view to exceeding 100m, fatigue becomes an increasingly critical performance consideration, and carbon in the spar becomes almost unavoidable. This, of course, has repercussions on blade materials and processing.

All-composite Lighthouse
The second video is of Acciona’s carbon and glass fiber/epoxy infused composite lighthouse built for the Port of Valencia.

Acciona, a longtime participant in the wind energy market, including as a turbine designer and builder, is also a world leader in infrastructure design and construction. It has recently pursued a variety of infrastructure projects using composites, including the Duque de Alba caissons for the Port of Rosario in the Canary Islands (see blog on that project’s fabrication partner Carbures), composite bridges and the new, all-composite lighthouse for the Port of Valencia, Spain. Why use composites? Because they enabled:
• Construction in about half the time of a steel equivalent;
• 20% reduction in carbon footprint vs. steel;
• A practically zero-maintenance structure;
• Energy self-sufficient structure due to integration of solar panels and small wind turbine.