摩擦副磨合过程摩擦因数时间序列分形行为研究

Study on Fractal Behavior of Friction Coefficient Time Series in the Running-in Process of Friction Pairs

为探究在油润滑条件下,涡旋压缩机端面摩擦副接触面在磨合初期与稳定磨损阶段摩擦因数局部时间序列曲线的分形行为,在TRB多功能摩擦磨损试验机上采用球墨铸铁分别与不同表面粗糙度的铜合金和铝合金进行摩擦磨损试验,采集磨合过程中摩擦因数的时间序列信号曲线并对其进行分形表征。结果显示:摩擦因数时间序列曲线具有明显的分形特征,可以根据摩擦过程中摩擦因数时间序列信号的分形维数来判断磨合过程的复杂程度;摩擦副在油润滑时表面粗糙度越大则磨合过程的平均摩擦因数越大,但摩擦因数曲线的分形维数越小,且磨合初期摩擦因数局部时间序列曲线的分形维数不规则波动越大;软质材料表面粗糙度的改变对摩擦因数及其局部分形维数的影响较大。

In order to investigatet he fractal behavior of the local time series curves about the friction coefficient of the contact surface of scroll compressor end-face friction at the initial running stage and stable wear stage under the oil lubrication condition,two friction and wear tests were performed on the TRB multifunctional friction and wear tester respectively with different materials such as the nodular cast iron and the copper alloy,the nodular cast iron and the aluminum alloy,all of which had different surface roughness. The time series signal curves of friction coefficient during the running process was collected and fractalized. The results show that the time series curves of friction coefficient had obvious fractal characteristic and the complexity of the running-in process can be judged according to the fractal dimension of the friction coefficient time series signal in the friction process. The greater surface roughness of the friction pairs during the oil lubrication,the greater the average friction coefficient,but the smaller the fractal dimension of the friction coefficient curves,and the more the irregular fluctuation of the fractal dimension of the local time series curves of the initial friction coefficient. The change of the soft material surface roughness has the greater effect on the friction coefficient and partial fractal dimension.