Researchers explain why feather shafts change shape when under stress

Date: December 12, 2016

Source: University of California - San Diego

Researchers at the University of California San Diego for the first time have revealed why the shape of the feather shaft changes from round to square when it's put under stress in a paper published in recent issue of Advanced Science. Nature almost always favors roundness. Only under special circumstances does it opt for square shapes. Examples include the cells of plants -- which derive their name from the square cells of monks. At a larger, structural level, there are a few rare examples: the seahorse tail, a vine found in the Amazon that has a square cross section, and the feather rachis.

In their study, using fundamental mechanics equations and experiments in modeling materials, researchers show that the square shape provides greater rigidity and higher resistance to ovalization and buckling than a hollow round shape of the same weight. "The most amazing thing is that this reflects textbook mechanics," said Marc Meyers, the paper's senior author and a professor of mechanical and aerospace engineering at the Jacobs School of Engineering at UC San Diego. "And obviously, birds haven't studied that subject."

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