湿式离合器磨合过程的多重分形谱预测

Multifractal spectrum prediction of the running-in process of wet clutch

针对湿式离合器试验过程中磨合状态的预测问题,结合试验过程中摩擦转矩信号的几何结构特征,提出利用多重分形谱及其参数来预测磨合状态的新方法。阐述了基于盒计数法计算多重分形谱的方法;给出了多重分形谱参数的定义及其与摩擦转矩信号之间的内在联系;利用多重分形谱及其参数对某型号湿式离合器磨合过程的摩擦转矩信号进行分形表征。分析结果表明:多重分形谱及其参数能够定量地刻画试验过程中摩擦转矩信号的几何特征,并且随着磨合过程的进行,谱宽、最大最小概率子集分形维数差及谱偏斜度都呈现逐渐减小趋势,而最小奇异指数则呈现逐渐增大趋势。因此,利用试验中摩擦转矩信号的多重分形谱能够有效地预测湿式离合器的磨合状态。

For predicting the running-in process of wet clutch test, a method based on multifractal spectrum and its parameters are proposed to predict the running-in state, combining with the geometry features of friction torque signal in test. Firstly, the concept of multifractal spectrum based on the box-counting method is introduced; and then the inherent relationship between the multifractal parameters and friction torque is discussed; finally, friction torque signals from a certain type wet clutch running-in test are analyzed and depicted by the multifractal spectrum and its parameters. The analytical results show that the geometry features of friction torque signals can be quantitatively described through multifractal spectrum and its parameters, and the breadth and fractal dimension difference of maximum-minimum probability subset of multifractal spectrum gradually decrease with the running-in process, while the minimum singularity exponent increases gradually with the running-in process. Therefore the running-in state of wet clutch can he effectively predicted by the multifractal spectrum of friction torque in test.