碳纳米锥力学特性的分子动力学研究

结合原子间短程作用势(Brenner势)和长程作用势(Lennard-Jones势),利用分子动力学方法对各种锥角的碳纳米锥进行拉伸和压缩实验,获得其载荷-应变关系曲线、受拉/压载荷极限、应变极限和构形演变等力学特性,并与等量原子组成的碳纳米管进行比较研究.研究结果表明,等量碳原子组成的碳纳米锥的受拉/压载荷极限随着锥角的增大先是增大后减小,受拉/压应变极限则随着锥角的增大而增大.与碳纳米锥相比,等量碳原子组成的碳纳米管的受拉/压载荷极限和应变极限显得既不突出也不逊色.在受压构形演化方面,与碳纳米管丰富的径向屈曲/扭转/侧向屈曲组合形变不同,112.88°和83.62°锥角的碳纳米锥受压沿轴向完美内陷,而60.0°和38.94°锥角的碳纳米锥受压发生侧向屈曲.

Study on the mechanical properties of carbon nanocones using molecular dynamics simulation

The mechanical behaviors of carbon nanocone (CNCs) with equivalent number of atoms under uniaxial extension and uniaxial compress are investigated using classical molecular dynamics simulations, exploring the Brenner and Lennard-Jones potentials to represent the interatomic interaction. The mechanical properties including elastic strain limit, ultimate longitudinal loading, and configuration evolution of CNC, are obtained and compared with those of carbon nanotube that consists of equivalent atoms. Under tension, CNC with larger apex angle presents a higher failure strength in general, as well as a larger maximum strain. However, the failure strength of the CNC with largest conical angle of 112.88° is the smallest one. The carbon nanotube with (15, 0) and 4 nm length presents a moderate strength and strain. Under compression, CNCs with conical angle of 112.88° and 83.62° have true chiral inversion without the chemical bond break. However, the other CNC exhibits unstable uniaxial compress and sudden lateral bend under compression. The force that buckles these carbon nanostructures decreases as the conical angle increases, except for the CNC of 38.94°. Results in the present study show that a certain CNC possesses more excellent mechanical properties than the equivalent CNT and is expected to substitute CNT and to be applied to some engineering fields such as nanosensors and nanoscale composites.