Effect of buckling regimes on the mechanical behavior of vertically aligned carbon nanotube arrays under shock compression: A molecular dynamics study

A Edalatmanesh and M Mahnama and MM Mashhadi, DIAMOND AND RELATED MATERIALS, 158, 112587 (2025).

DOI: 10.1016/j.diamond.2025.112587

The effect of carbon nanotube (CNT) diameter on the structural evolution and mechanical properties of vertically aligned carbon nanotube (VACNT) arrays under ultra-high strain rate shock compression remains an open question. To address this, molecular dynamics simulations using the Hugoniostat method were conducted on VACNT arrays consisting of CNTs with varying diameters and a fixed length of 10 nm. The findings indicate that for VACNT arrays with thinner CNTs, the dominant buckling mode follows an Euler beam-like pattern, where the critical buckling limit increases with CNT diameter. Conversely, for VACNT arrays with larger CNTs, a shell-like buckling mode is activated, leading to a decrease in the buckling critical limit as CNT diameter increases.Further analysis of atomistic evolution under high-strain-rate compression shows that larger CNT arrays undergo a partial phase transition (PPT) from sp2 to sp3 hybridized carbon atoms at higher strains (greater densification). However, these arrays exhibit a lower sp3 fraction after PPT. Mechanical testing reveals that although VACNT arrays with larger CNTs have lower ultimate compressive strength post- PPT, they experience a greater reinforcement effect. These insights into the interplay between buckling regimes and phase transition behavior enhance our understanding of VACNT arrays under extreme conditions, offering potential applications in strain sensors, flexible electronics, and energy storage devices.

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