Aerospace Science and Technology
ali Vahedi; Mohammad Homayoun Sadr; Saied Shakhesi
Abstract
Epoxy is among the most important polymers, which is extensively employed in various technologies and applications. Nevertheless, epoxy polymers present low thermal conductivities and thus the enhancement of their thermal conductivity is an important research topic. Carbon nanotubes (CNTs) owing to their ...
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Epoxy is among the most important polymers, which is extensively employed in various technologies and applications. Nevertheless, epoxy polymers present low thermal conductivities and thus the enhancement of their thermal conductivity is an important research topic. Carbon nanotubes (CNTs) owing to their excellent thermal conductivities have been widely considered for the enhancement of the thermal conduction of epoxy polymers. In this work, we developed a combined molecular dynamics finite element multiscale modelling to investigate the heat transfer along CNT/epoxy nanocomposites. To this aim, the heat transfer between the CNT and epoxy atoms at the nanoscale was explored using the atomistic classical molecular dynamics simulations. In this case, we particularly evaluated the interfacial thermal conductance between the polymer and fillers. We finally constructed the continuum models of polymer nanocomposites representative volume elements using the finite element method in order to evaluate the effective thermal conductivity. The developed multiscale modelling enabled us to systematically analyze the effects of CNT fillers geometry (aspect ratio), diameter and volume fraction on the effective thermal conductivity of nanocomposites. Our results suggest that the interfacial thermal conductance between the CNT additives and epoxy polymer dominate the heat transfer mechanism at the nanoscale.The obtained findings in this study provide good vision regarding the enhancement of thermal conductivityof polymeric materials using highly conductive nanofillers.
Maysam gelveh; S. Mojtaba Mosavi; Mohammad Homayoun Sadr
Abstract
In the last decade, nonlinear normal modes have attracted the attention of many researchers, and many methods and algorithms have been proposed to calculate them. Among the proposed methods, the combination of the shooting method and the continuation of the periodic solution is the strongest methods. ...
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In the last decade, nonlinear normal modes have attracted the attention of many researchers, and many methods and algorithms have been proposed to calculate them. Among the proposed methods, the combination of the shooting method and the continuation of the periodic solution is the strongest methods. However, the computational cost of the method has still limited its application. In this paper, an updated formula is used to reduce the computational costs of the method. Using this updated formula significantly reduced the computation time so that the computational speed of nonlinear normal modes increased tenfold. Also, as the power of nonlinear terms increases in the system, the efficiency of the updated formula increases. In order to evaluate the accuracy of the proposed method, a system with two degrees of freedom was studied, and it was observed that the results obtained are consistent with the results in other works.