磨合是各运动副在投入运行前为获得好的配合性、提高承载能力所必须经历的过程，表面形貌的明显变化是磨合过程中表现出的重要特征。本文引入分形理论，用分形参数表征磨合表面的形貌变化。研究表明，磨合表面变化的分形参数表征是简单有效的。

The fractal dimension and scale coefficient of surface profiles were calculated using the structure function method. Studies show that fractal dimension or scale coefficient is not optimum in characterizing rough surfaces. In consideration of this case, a fractal parameter called the characteristic roughness is put forward by combining the profile fractal dimension and the scale coefficient. Its definition and calculation expression are given. Running-in wear tests were conducted by using a thrustwasher type tester, and surface topographies were measured in the same area of the test specimens at different wear times. Experimental results show that the characteristic roughness parameter is not only more objective but also more sensitive to characterize wear surfaces during the running-in process than fractal dimension or scale coefficient.

To find a more accurate method characterizing wear particles, fractal geometry is applied in this paper describing wear particle accumulation. The wear experiments are carried out on a pin-on-disc test rig under dry friction conditions for a copper alloy pin and a steel disk. The results demonstrate that the logarithm of wear particle accumulation shows good linearity with the logarithm of the measured particle size. The relation between the accumulation of wear particles and the particle size presents a strong bi-fractal behavior. In addition, it is discovered that the fractal dimension of wear particle accumulation changes in different wear stages. The changes of the transition points of the bi-fractals correspond to the wear state variations.

Fractal geometry is applied to the characterization of rough surfaces. The variation law of surface topography during running-in period is studied with scale-independent fractal parameters. The theoretical relation of real contact area between rough surfaces to profile fractal parameters, material properties and load, etc. is obtained. Using the relation and Rowe’s modified adhesion theory, a fractal model of running-in wear is developed. Theoretical analysis and experimental researches show that the result calculated by this wear models are consistent with the experiments. q1999 Elsevier Science S.A. All rights reserved.

Taking the chock shield supports as the object of study, methods for measuring and calculating the external load of powered supports were discussed. Selecting the angle parameters as variables, the simple formulae of interactive computation with respect to the work angles of a powered support were deduced and verified by an example. Furthermore, the formulae determining the magnitude, direction and action point of the external load were put forward. The investigation results have provided a sound basis for the software design of the intelligent instrument for load measuring of powered supports.

阐述了表面轮廓分形和分形曲线的基本概念，对目前常用于表面轮廓分形维数的4种计算方法的基本思路作了评介，指出这些方法的计算结果都存在一定的偏差，对选择不同计算尺度得到的分形维数表现出较大的不稳定性，致使分形维数难以准确地反映表面轮廓的真实复杂特征。根据表面轮廓的均方差与区间尺度成比例的性质，提出了表面轮廓分形维数计算的协方差加权法。通过与Weierst rass-Mandelbrot分形函数曲线的分形维数计算的比较，协方差加权法所得表面轮廓分形维数的稳定性良好，计算结果的准确性也明显提高，可以简化表面形貌的识别过程，为摩擦学研究中更准确地描述粗糙表面的复杂特征提供了一种简便适用的新方法。

在工程实际中，对新机器零件的抗磨可靠性寿命进行评估或预测非常重要。但是，由于磨损是一种受多因素制约的随机过程，目前在实验室广泛采用的模拟磨损试验，不仅周期较长，而且预测误差也比较大。因此，提出了一种在保持磨损机理相似的前提下合理选用高PV值的抗磨可靠性寿命加速试验的新方法。根据可靠性设计原理和抗磨可靠性数值计算，着重研究了滑动磨损的多样品抗磨可靠性寿命的加速试验方法，包括加速系数的确定、抗磨寿命分布参数的估计、抗磨可靠性寿命的预测及其置信度的估计等。

在销-盘摩擦磨损试验机上考察45#钢-铜合金摩擦副的磨损性能，按一定时间间隔收集磨损过程中积聚的金属磨粒，然后用光学显微镜对不同粒径范围内的磨粒进行计数和分形研究。研究结果表明：不同粒径的金属磨粒所对应的积聚数呈现明显的分形特征，小磨粒积聚和大磨粒积聚表现出不同的分形特征，并具有双重分形现象；磨损过程中的磨粒积聚分形特征对应于某一粒径尺度的分形转折点，该分形转折点的坐标位置与磨损状态相关，因此确定分形转折点有助于甄别磨损状态。

利用触针轮廓仪和数据采集系统对磨削和车削表面的粗糙轮廓曲线进行了测量，并就粗糙表面的分形特征作了分析与讨论，同时还提出了粗糙表面的特征粗糙度概念及其定义，并将其用于表面粗糙度水平的表述。研究结果表明：粗糙表面具有明显的分形特征，而且能够通过常规轮廓仪测量和适当的计算方法得到它的分形维数；加工表面具有二重分形特征，第二分形的起点尺度与相关长度几乎成正比；第一分形维数与粗糙度的关系可以用负指数描述；特征粗糙度结合分形维数的相似测量和尺度参数的绝对测量，其数值能够表达表面的粗糙度水平；特征粗糙度不仅能体现表面多尺度测量的标度律特性，而且又不失表达粗糙度的灵敏性和准确性。