Load-transfer and failure behaviors of crosslinked interfaces in collagen-mimic carbon nanotube bundles
Load-transfer and failure behaviors of crosslinked interfaces in collagen-mimic carbon nanotube bundles
复制标题
模拟胶原碳纳米管束中交联界面的载荷传递和失效行为
DOI：
10.1016/j.ijmecsci.2017.11.036
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发表时间：
2018
影响因子：
7.3
通讯作者：
Zhang Zuoqi
中科院分区：
文献类型：
--
作者：
Lin Min;Sun Xiaoyu;Xie Wen;Zhang Zuoqi
界面薄弱一直是阻碍碳纳米管(CNTs)超高硬度和强度作为增强材料开发的瓶颈。受胶原纤维结构的启发，一种用于超强碳纳米管束的共价交联界面设计引起了人们的广泛关注。本文采用分子动力学模拟方法系统地研究了交联界面的载荷传递能力和破坏行为，包括交联剂类型(长度)、密度和界面长度的影响。我们发现少量的共价交联剂可以显著提高界面的刚性和强度。较短的交联键通常会产生较高的界面刚度，而较长的交联键通常会产生较高的界面强度。随着交联剂密度和界面长度的变化，出现了三种主要的失效模式，即突发性界面失效、渐进性界面失效和碳纳米管断裂。第四种失效模式也出现在最优界面设计上，在这种模式下，键断裂在交联界面和碳纳米管中同时且逐渐地传播。优化设计可以同时提供优良的刚度、强度和韧性，因此在工程应用中具有很高的应用价值。这些发现为高性能碳纳米管纤维的界面设计提供了有用的见解。
Weak interface has been a long-standing bottleneck critically hindering the exploitation of the ultra-high stiffness and strength of carbon nanotubes (CNTs) as reinforcement materials. Inspired by the structure of collagen fibril, a covalently cross-linked interface design for ultra-strong CNT bundles has attracted a lot of attentions. In the present paper, molecular dynamics simulations were conducted to systematically study the load-transfer capacity and failure behaviors of the crosslinked interface, including the influence of crosslink type (length), density, and interface length. We found that a small number of covalent crosslinks can significantly enhance the interface stiffness and strength. The shorter crosslinks usually yield higher interface stiffness while the longer crosslinks generally produce higher interface strength. There are three major failure modes unveiled as the crosslink density and interface length vary, namely the abrupt interface failure, the gradual interface failure and the CNT break. A forth failure mode was also seen upon an optimal interface design, in which bond breaks propagate simultaneously and gradually in crosslinked interfaces and CNTs. The optimal design is highly desired in engineering applications since it can simultaneously provide superior stiffness, strength and toughness. These findings provide useful insights into the interface design of high-performance CNT fibers.