Mechanical properties of helically twisted diamond nanothread fibers

Y Li and XY He and XQ Ma and XM Chen and JY Wu and YW Lin, INTERNATIONAL JOURNAL OF MECHANICAL SCIENCES, 304, 110726 (2025).

DOI: 10.1016/j.ijmecsci.2025.110726

Diamond nanothread (DNT), which combines the advantageous properties of inorganic nanostructures and hydrocarbon molecular systems, exhibits exceptional mechanical characteristics. Here, the role of helical twist angle (alpha) on the uniaxial tensile properties of DNT fibers fabricated by twisting 6 DNTs with hexagonal-packed configuration is explored by classic molecular dynamics (MD) simulations, which is expected to solve the problem of small radial dimensions in their engineering applications. The MD results show that both the twisted morphology and mechanical performance of DNT fibers are critically governed by alpha. Stress-strain profiles exhibit distinct characteristics depending on alpha, with mechanical properties including Young's modulus, tensile strength, fracture strain, and deformation mechanisms, showing pronounced alpha dependency. Notably, Young's modulus decreases monotonically across the full alpha (0 degrees-360 degrees), while fracture strain increases with higher alpha. Furthermore, the failure mechanisms transition from brittle fracture in low-angle configurations to progressive, ductile-like unraveling in highly twisted fibers. These findings provide atomic-level insights into the structure-property relationships of DNT fibers, establishing mechanical twist operation modulation as a powerful design parameter for tailoring their mechanical performance in applications such as nano- reinforced composites, flexible electronics, and energy-absorbing materials.

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