The recent progress of functionally graded CNT reinforced composites and structures

In the last decade,the functionally graded carbon nanotube reinforced composites(FG-CNTRCs)have attracted considerable interest due to their excellent mechanical properties,and the structures made of FG-CNTRCs have found broad potential applications in aerospace,civil and ocean engineering,automotive industry,and smart structures.Here we review the literature regarding the mechanical analysis of bulk CNTR nanocomposites and FG-CNTRC structures,aiming to provide a clear picture of the mechanical modeling and properties of FG-CNTRCs as well as their composite structures.The review is organized as follows:(1)a brief introduction to the functionally graded materials(FGM),CNTRCs and FG-CNTRCs;(2)a literature review of the mechanical modeling methodologies and properties of bulk CNTRCs;(3)a detailed discussion on the mechanical behaviors of FG-CNTRCs;and(4)conclusions together with a suggestion of future research trends.

Nanoarray-Embedded Hierarchical Surfaces for Highly Durable Dropwise Condensation

Durable dropwise condensation of saturated vapor is of significance for heat transfer and energy saving in extensive industrial applications.While numerous superhydrophobic surfaces can promote steam condensation,maintaining discrete microdroplets on surfaces without the formation of a flooded filmwise condensation at high subcooling remains challenging.Here,we report the development of carbon nanotube array-embedded hierarchical composite surfaces that enable ultra-durable dropwise condensation under a wide range of subcooling(ΔT_(sub)=8 K–38 K),which outperforms existing nanowire surfaces.This performance stems from the combined strategies of the hydrophobic nanostructures that allow efficient surface renewal and the patterned hydrophilic micro frames that protect the nanostructures and also accelerate droplet nucleation.The synergistic effects of the composite design ensure sustained Cassie wetting mode and capillarity-governed droplet mobility(Bond number<0.055)as well as the large specific volume of condensed droplets,which contributes to the enhanced condensation heat transfer.Our design provides a feasible alternative for efficiently transferring heat in a vapor environment with relatively high temperatures through the tunable multiscale morphology.

Atomistic Insights into the Tunable Transition from Cavitation to Crazing in Diamond Nanothread-Reinforced Polymer Composites

Cavitation and crazing in thermosetting polymers can be sophisticatedly designed for valuable applications in optics,electronics,and biotechnology.It is a great challenge for numerical study to describe the formations of cavity and fibrils in polymer composite due to the complicated interfacial interaction.To explore this challenging task,we exploit a two-phase coarse-grained framework which serves as an efficient atomistic level-consistent approach to expose and predict the transition between cavitation and crazing in a polymeric system.The coarse-grained framework is utilized to transmit the information between single phase and interface in polymer composite,and the learning tasks of force field are fulfilled through parameterization of mechanical performances and structural characterizations.We elaborate on the intrinsic characteristics of the cavitation-crazing transition in diamond nanothread-(DNT-)reinforced polymethyl methacrylate composites,in which DNT plays a specific role of nanomodulator to tune the cavity volume ratio.The transition from cavitation to crazing can be induced through a novel dissipative mechanism of opening an interlocked network,in which case the DNT is stretched to the aligned fibrils and links crazing tightly by interfacial adhesion.The designed computational framework can broaden the scope of theoretical tools for providing better insights into the microstructure design of polymer composites.