Continuum and atomistic scale computational mechanics for structures with small length scales. With on-demand call to molecular dynamics simulations and scale up to continuum level constitute models, where predictions can be made for laboratory accessible time and length scales.

Material systems including: crystal plasticity in singly/poly crystalline metals, interfacial/grain-boundary mechanics in nanostructured materials, amorphous solids, nanowires, soft materials.

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力学所在二维材料中的纳米级褶皱实现其三维结构的高强度和高韧性研究中取得进展

 

       近日,力学所非线性力学国家重点实验室魏宇杰研究团队通过原子尺度模拟和理论分析,报道了高强度和高韧性的堆叠无定形碳基复合材料,并揭示了纳米级褶皱产生的增强增韧这一反常规机制。该工作近期发表在国际权威期刊Nano Letters上。 

       石墨烯等低维碳基材料具有极高的面内强度和杨氏模量,但其三维堆叠结构难以继承这些优势且表现出极端脆性。该团队通过模拟和理论分析,设计了基于二维无定形碳薄膜的堆叠结构,与大多堆叠结构材料不同的是,它们同时实现了高强度(GPa)和类塑性的大变形。对变形过程分析发现,大量初始缺陷引起的表面粗糙度和单原子层固有的面外柔性是其增强增韧的两个关键因素。在拉伸过程中,表面大量的纳米级褶皱会带来不均匀的小尺度层间界面滑移,从而导致剪应力的不均匀分布和类塑性变形,避免了材料的突然失效。这些结论对其他类型的原子尺度薄膜材料具有普遍性,为提高范德华异质结构的韧性,有效避免灾难性失效提供了新的策略。 

       论文以力学所博士研究生谢文慧为第一作者,魏宇杰研究员为通讯作者。该工作得到了国家自然科学基金委 (No. 11988102; No. 11790291)和中国科学院先导专项(XDB22020200)的支持。

       论文链接: https://doi.org/10.1021/acs.nanolett.1c01462

图:二维无定形碳的三维堆叠,由此产生的非晶碳基复合材料具有高强度(~3.5 GPa)和良好的韧性。堆叠结构示意图和原子构型(左),层中的纳米级褶皱是增强增韧源头;堆叠片层尺寸b对复合材料力学性能的影响(右)。

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