A robotic laboratory that can run 50 experiments a day without human supervision has discovered the most energy-absorbing structure ever recorded, claim researchers.
A robotic laboratory that can produce and test mechanical structures without human supervision has discovered the most energy-absorbing one measured so far, beating the previous record held by balsa wood.
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| The Bayesian experimental autonomous researcher (BEAR), a robotic laboratory Aldair E. Gongora and Bowen Xu |
There are many ways to test how tough or resilient a structure is, but one common measure is the energy absorbing efficiency, or the amount of mechanical energy something can absorb without failing.
Protective structures, like the foam in bike helmets or the metal in car crumple zones, tend to have high energy-absorbing efficiencies so that the mechanical energy from a crash isn’t transferred to the person involved, which could cause injury.
Keith Brown at Boston University in Massachusetts and his colleagues say they have discovered a class of material structures with the highest energy-absorbing efficiency ever measured, using an autonomous robotic laboratory called the Bayesian experimental autonomous researcher (BEAR).
“We built a system that designs mechanical structures, tests them and then uses the results of all previous tests to design and test additional structures,” says Brown. “It runs in a closed loop and it’s totally autonomous.”
BEAR consists of five 3D printers that can produce seven different kinds of plastics, a set of scales and a testing machine that can compress each structure it makes from the plastics and measure its response, as well as a robotic arm and a computer vision system to move the samples around.
The laboratory performed more than 25,000 experiments, at a rate of about 50 per day, although only just over half of them produced valid data. While the experimentation was entirely autonomous, there were several points during the testing run when Brown and his team intervened, such as telling BEAR the point at which a sample would break, or adjusting the temperature for a section of the manufacturing procedure.
Brown and his team found different high-performing structures, depending on the plastic used. For example, a structure they called Willow, shaped like a twisted, elongated four leaf clover, performed best when made out of a kind of polyester called PLA, measuring an average efficiency of 73.3 per cent, which means it absorbs that percentage of the energy.
This beat the previous most energy absorbing example the researchers could find records of, balsa wood, at 71.8 per cent efficiency.
However, Willow didn’t perform as well when made out of other materials, and each of the plastics the lab uses appeared to have its own best-performing structure. It is unclear whether structures like Willow might perform well if made from other materials, says Brown.
Testing substances without the need for human intervention could help quicken the discovery of many new materials, says Iman Mohagheghian at the University of Surrey, UK. “All these experiments are extremely labour intensive. If you have something that can work 24/7 in the lab, there will be an acceleration in materials studies.”
These structures might be relevant for something like a bike helmet, says Devesh Mistry at the University of Leeds, UK, but they will need to be further investigated to make sure they work in different impact scenarios.
It will be interesting to see whether these structures can outperform the relatively cheap, existing alternatives, such as expanded polystyrene, he says.
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