Open Access

ARTICLE

Estimation of the Mechanical Property of CNT Ropes Using Atomistic-Continuum Mechanics and the Equivalent Methods

C.J. Huang¹, T.Y. Hung¹, K.N. Chiang²

1 Research Engineer, TSMC/NTHU, Hsinchu, Taiwan, R. O. C.
2 Corresponding Author, NTHU, Hsinchu, Taiwan, R. O. C.; E-mail: knchiang@pme.nthu.edu.tw; Tel: +886-3-571-42925; Fax: +886-3-574-5377.

Computers, Materials & Continua 2013, 36(2), 99-133. https://doi.org/10.3970/cmc.2013.036.099

Abstract

The development in the field of nanotechnology has prompted numerous researchers to develop various simulation methods for determining the material properties of nanoscale structures. However, these methods are restricted by the speed limitation of the central processing unit (CPU), which cannot estimate larger-scale nanoscale models within an acceptable time. Thus, decreasing the CPU processing time and retaining the estimation accuracy of physical properties of nanoscale structures have become critical issues. Accordingly, this study aims to decrease the CPU processing time and complexity of large nanoscale models by utilizing, atomistic-continuum mechanics (ACM) to build an equivalent model of carbon nanotubes (CNTs). The results of tensile and modal analyses agree with previous experimental results indicating that the ACM model can accurately describe mechanical properties. This study also adopted three definitions of cross-sectional area to explore whether the structure properties of CNT ropes depends on the definitions of cross-sectional area. Results indicate that the Young’s modulus distribution based on the circumcircle assumptions agrees well with most of the experimental results. Hence, most experimental methods adopted the circumcircle to obtain the Young’s modulus of the CNT ropes. The circumcircle assumption involves the distribution of the tubes and the gap between each tube. The ratio between the gap and tube areas becomes a stable value when the diameter of the CNT ropes is increased. Therefore, a larger diameter of CNT ropes that represents the Young’s modulus becomes a stable value, as mentioned in literature. This study also investigated the equivalent solid, shell, and beam models to generate similar mechanical behaviors with the ACM model. The similar mechanical behavior of the equivalent model includes the model under tensile, torsion, or shear external loading. These equivalent models can significantly reduce the required total element number and CPU processing time to investigate a larger nanoscale structure.

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