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A team of undergraduate engineering students at the University of California San Diego has discovered a method that could make materials more resilient against massive shocks such as earthquakes or explosions. “This research can be used in military applications and civil applications too, to design materials and buildings to better withstand high-intensity blasts,” said Christina Scafidi, one of the authors of the paper and a 2019 structural engineering graduate.

“The coal industry has had many fatal accidents and we believe this research presents a strong case for protecting the workers from blast waves that can easily propagate throughout an entire coal mine,” added Alexander Ivanov, a recent aerospace engineering graduate and co-author of the paper. “If the entire wall of the coal mine could be lined with these solid geometric obstacles, it could provide a cheap way to protect all of the workers in the mine.”

The students used a shock tube to generate powerful explosions within the tube — at Mach 1.2 to be exact, meaning faster than the speed of sound. They then used an ultra high-speed camera to capture and analyze how materials with certain patterns fared.

The team’s previous work showed that obstacles laid out in a logarithmic spiral were better able to diminish the energy of a shock wave and reduce overall damage than when arranged in other patterns. The students took that a step further, testing whether cutting three grooves into each side of their rectangular obstacle materials would be an even better attenuator of the shock when compared with similar obstacles laid out in a logarithmic spiral but with no grooves.

The research team found that these grooves did indeed diminish the impacts of what’s called the reflected shock wave — once the initial wave has hit the spiral of obstacles and bounced back. Results were inconclusive for the initial transmitted shock wave, according to 

Findings were reported in the journal Multiscale and Multidisciplinary Modeling, Experiments and Design.