College of Water Resources and Architectural Engineering, Northwest A&F University, Yangling, 712100, China.
Research School of Engineering, the Australian National University, Canberra, ACT, 2601, Australia.
Sci Rep. 2017 Jul 28;7(1):6772. doi: 10.1038/s41598-017-07184-x.
In a short nanobearing system made from carbon nanotubes, the rotor with high rotational frequency may escape from the stator, which may cause a stability problem to the system of a nanodevice with such a nanobearing. In the present work, nanobearings with tri-walled nanotubes are investigated to reveal the conditions for the moving away of the free inner tube from the high-speed rotating middle tube. Experimental results show that the escape happens when the radii difference between the two rotors is larger than 0.34 nm and the rotational frequency of the middle tube is higher than a critical value. And before the escape occurs, the rotational frequency of the inner tube is lower than this critical value. Due to the radii difference being larger than 0.34 nm, the two rotors are non-coaxial, and the centrifugal force of the inner tube results in strong radial and axial interactions between the edges of the two rotors. When the relative sliding speed is relatively high, an edge of the inner rotor will pass through the potential barrier at the adjacent edge of the middle rotor, and further escape from the middle rotor occurs. The selection of a longer middle rotor with smaller radius can increase the critical rotational frequency of the middle rotor.
在由碳纳米管制成的短纳米轴承系统中，具有高旋转频率的转子可能会从定子中逸出，这可能会导致带有这种纳米轴承的纳米器件系统出现稳定性问题。在本工作中，研究了具有三壁纳米管的纳米轴承，以揭示自由内管从高速旋转的中间管中移出的条件。实验结果表明，当两个转子的半径差大于 0.34nm 且中间管的旋转频率高于临界值时，就会发生逃逸。并且在逃逸发生之前，内管的旋转频率低于此临界值。由于半径差大于 0.34nm，两个转子不是共轴的，内管的离心力导致两个转子边缘之间存在强烈的径向和轴向相互作用。当相对滑动速度较高时，内转子的一个边缘将穿过中间转子相邻边缘的势垒，进一步发生从中转子逸出的现象。选择半径较小的较长中间转子可以增加中间转子的临界旋转频率。
