Buckling behavior of nanowires predicted by a new surface energy density model
Buckling behavior of nanowires predicted by a new surface energy density model
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DOI：
10.1007/s00707-016-1597-2
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发表时间：
2016-03
期刊：
影响因子：
2.7
通讯作者：
Yin Yao;Shaohua Chen
中科院分区：
文献类型：
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作者：
Yin Yao;Shaohua Chen
采用新的连续介质理论研究了纳米线的轴向屈曲行为，其中纳米材料的表面效应由表面能密度表征。该方法只考虑了块体材料的表面能密度和表面弛豫参数，而不考虑经典表面弹性理论中的表面弹性常数。讨论了两种不同边界条件的纳米线。结果表明，新的连续介质理论可以很好地预测纳米线的屈曲行为。与经典弹性理论的预测结果相似，新连续介质理论预测的纳米线轴向屈曲临界载荷随着特征长度（如纳米线直径或高度）的增加而增加。在相同的长径比下，矩形截面的纳米线比圆形截面的纳米线具有更大的临界屈曲载荷。然而，表面效应可以提高临界屈曲载荷不仅为固定-固定的纳米线，而且为悬臂的一个在经典的弹性模型相比。新的连续介质理论的预测结果与表面弹性模型的预测结果吻合得很好。本研究不仅验证了新的连续介质理论的有效性，而且提供了一个更方便的表征纳米线的屈曲行为。这对于基于纳米材料的纳米器件的设计，例如NEMS或高精度仪器中的纳米梁，应该是有帮助的。
The axial buckling behavior of nanowires is investigated with a new continuum theory, in which the surface effect of nanomaterials is characterized by the surface energy density. Only the surface energy density of bulk materials and the surface relaxation parameter are involved, instead of the surface elastic constants in the classical surface elasticity theory. Two kinds of nanowires with different boundary conditions are discussed. It is demonstrated that the new continuum theory can predict the buckling behavior of nanowires very well. Similar to the prediction of the classical elasticity theory, the critical compressive load of axial buckling of nanowires predicted by the new continuum theory increases with an increasing characteristic length, such as the diameter or height of nanowires. With the same aspect ratio, a nanowire with a rectangular cross section possesses a larger critical buckling load than that with a circular one. However, the surface effect could enhance the critical buckling load not only for a fixed–fixed nanowire but also for a cantilevered one in contrast to the classical elastic model. All the results predicted by the new continuum theory agree well with predictions by the surface elasticity models. The present research not only verifies the validation of the new continuum theory, but also gives a much more convenient characterization of buckling behaviors of nanowires. This should be helpful for the design of nanodevices based on nanomaterials, for example, nanobeams in NEMS or high-precision instruments.