Self Healing Hulls

Electric current could be the key to self-healing carbon-composite smart materials

2 min read

Among the claims to fame of Switzerland’s Ecole Polytechnique Fédérale de Lausanne (EPFL) is Alinghi , the yacht, which won not one but two America’s Cups. Part of that success can be attributed to the state-of-the-art carbon-fiber composites that make up Alinghi ’s hull. In many cases, such composites can substantially heal themselves following a collision. Now a graduate student has invented a way to juice the self-healing with a little electric current.

EPFL doctoral student Eva Kirkby is developing a better way for carbon-composite materials to heal themselves. Carbon-fiber composites, made from many layers of lightweight carbon fibers and epoxy, offer a strength-to-weight ratio much higher than that of similar-weight materials. They’re often found in Formula One race cars, and they make up 50 percent of the Boeing 787 airliner. But one weakness of these superstrong materials is a tendency to separate internally, or delaminate, when big impacts cause cracks parallel to the surface of the material. Delamination damage can decrease the composite’s strength by an order of magnitude.

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Deep Learning Could Bring the Concert Experience Home

The century-old quest for truly realistic sound production is finally paying off

12 min read
Image containing multiple aspects such as instruments and left and right open hands.
Stuart Bradford

Now that recorded sound has become ubiquitous, we hardly think about it. From our smartphones, smart speakers, TVs, radios, disc players, and car sound systems, it’s an enduring and enjoyable presence in our lives. In 2017, a survey by the polling firm Nielsen suggested that some 90 percent of the U.S. population listens to music regularly and that, on average, they do so 32 hours per week.

Behind this free-flowing pleasure are enormous industries applying technology to the long-standing goal of reproducing sound with the greatest possible realism. From Edison’s phonograph and the horn speakers of the 1880s, successive generations of engineers in pursuit of this ideal invented and exploited countless technologies: triode vacuum tubes, dynamic loudspeakers, magnetic phonograph cartridges, solid-state amplifier circuits in scores of different topologies, electrostatic speakers, optical discs, stereo, and surround sound. And over the past five decades, digital technologies, like audio compression and streaming, have transformed the music industry.

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