基于 Lennard-Jones 势的界面摩擦黏滑行为动力学研究

目的研究界面摩擦过程中,原子间的相互作用关系及规律。方法基于Lennard-Jones(L-J)势理论,建立界面摩擦黏滑行为的非线弹性振子模型,并以α-Fe晶体为例进行仿真分析。结果在假设条件下,质块振动主振频率约为16 Hz;运动端宏观速度v=1×10-3m/s是主振幅值增大的临界值;刚度系数k和阻尼系数c分别在1.0~100 N/m,1.0×10-4~1.0×10-1N/(m/s)范围内变化时,粘滑频率和主振频率分别随二者的增大而提高;摩擦界面真实接触面积S在1.0×10-18~1.0×10-14m2内变化时,增大摩擦界面间的法向压力将导致黏滑强度增大。仿真计算表明:摩擦界面单个原子受到的激励力与原子间作用势及晶格常数有关,质块的黏滑行为与激励力、相对滑动速度、质块质量、系统刚度系数、系统阻尼系数及真实接触面积等内外因素有关。结论相对滑动速度或真实接触面积增大时,黏滑强度增强;质块质量、系统刚度系数、系统阻尼系数增大时,黏滑强度减弱。系统刚度系数、系统阻尼系数增大时,黏滑频率增大;质块质量增大时,黏滑频率减小;相对滑动速度、真实接触面积对黏滑频率的影响不显著。

Dynamics of Stick-slip on Interfacial Friction Based on the Lennard-Jones Potential Theory

Objective To study the interaction relationship and discipline between atoms in interface friction process. Methods A non-linear elastic oscillator model of stick-slip friction during interfacial friction was established based on Lennard-Jones potential theory, then alpha Fe crystal was taken as an example and simulation experiment was conducted. Results Under the condition of hypothesis, the main vibration frequency of the mass was 16 Hz; the macro velocity equaling to v = 1×10 -3 m / s was the critical value of the increase of main amplitude values. The stick-slip frequency and main vibration frequency increased respectively along with the augment of the stiffness and damping coefficient in the ranges of 1. 0 ~ 100 N / m and 1. 0×10 -4 ~ 1. 0×10 -1 N / (m / s), respectively. When the real contact area of friction interface ranged from 1. 0×10 -18 to 1. 0×10 -14 m2 , increasing the normal pressure of friction interface caused the augment of stick-slip intension. The simulation calculation results showed that the excitation force on the upper interface atoms was related to the interatomic potential and the lattice constants, and the stick-slip behavior was related to the excitation force, relative sliding velocity, block mass, system stiffness, damping coefficient and the real contact area. Conclusion When the relative sliding velocity or real contact area increased, the stick-slip intensity increased. When the mass of the sliding block or system stiffness, damping coefficient increased, the stick-slip strength was weakened. When the system stiffness or damping coefficient increased, the stick-slip frequency increased. When the mass of the sliding block increased, the stick-slip frequency decreased. The effects of the relative sliding velocity and the real contact area on the stick-slip frequency were not significant.