On March 13, a landmark study led by Professor (Research Fellow) Fang Xin from National University of Defense Technology (NUDT) achieved a major breakthrough in mechanical metamaterials. Their paper "Large Recoverable Elastic Energy in Chiral Metamaterials via Twist Buckling" was published in the prestigious journal Nature . NUDT is the primary affiliation, with Fang Xin, born in the 90s, is both the first author and a co-corresponding author. Other co-authors include Yu Dianlong, Wen Jihong, Dai Yifan, Gao Huajian, and Peter Gumbsch.
Structures and materials combined high stiffness, high strength and large recoverable strain are much anticipated in widespread engineering applications, but existing structures and materials struggle to the compromise between high strength and high toughness, posing a global challenge. To address this challenge, the research team proposed a new mechanism: creating chiral metamaterials with freely rotatable chiral metacells, which can induce torsional buckling deformation under compression—a buckling mode has never been well understood.
After four years of exploration and over thirty attempts at modeling approaches, Fang Xin found the analytical solution of the chiral twist buckling problem, establishing the Chiral Twist Buckling Theory, which marks a significant leap forward in addressing the long-standing challenges in rod torsional mechanics. Extensive experimental and theoretical analyses demonstrate that: compared with existing non-chiral structures, even non-optimized chiral metamaterials maintain high stiffness and achieve larger recoverable deformation, improving buckling strength by 5-20 times and enhancing recoverable elastic energy density by 5-160 times, exceeding traditional material performance limits. The Chiral Twist Buckling Theory elucidates the mechanism behind the combination of high stiffness and high-energy characteristics, offering an essential solution for aerospace, marine, high-speed rail, and automotive industries.
By: Fang Xin, Yang Yuxin, Zhang Zengqiang