磨合过程摩擦力单重分形和多重分形的研究

分别在CD40润滑油和加入添加剂的CD40润滑油润滑条件下,通过销-盘摩擦磨损试验机对船用柴油机活塞环和缸套进行磨合磨损试验,提取摩擦力的时间序列信号,应用分形维数和多重分形谱研究了摩擦力的分形行为.结果表明:摩擦力信号具有分形特征;随着磨合磨损过程的进行,信号的分形维数和多重分形谱出现规律性的变化;不同阶段信号的分形维数趋于减小,与磨损表面粗糙度的变化规律一致;不同阶段信号的多重分形谱呈现出递增或递减趋势,反映了磨损表面的动态变化过程.因此,摩擦力信号的分形维数和多重分形谱可以对磨合磨损过程进行定量分析.

Study on Single Fractal and Multifractal of Frictional Forces in the Running-in Process

Running-in and wear tests of a piston ring against a cylinder were conducted on a pin-on-disc tester, lubricated by both of CD40 lubricant and CD40 lubricant with additive. The sequence signals of the friction force were collected. The fractal behavior of the frictional forces was studied by means of fractal dimension and muhifractal spectrum. The sequence signals of the friction force are characterized by fractal, and the fractal dimension and muhifractal spectrum of the signals assume a regular variation in the running-in process. The variation of fractal dimension is coincident with the evolution of surface roughness, and the muhifractal spectrum can be used to describe dynamic process of friction surface. Therefore the quantitative analysis of running-in process can be carried out by fractal dimension and muhifractal spectrum of the sequence signals of the friction force.