Evolvement rule of running-in attractor

In order to know the dynamic behavior and its change regularity of wear process, the running-in attractor is studied with fractal and chaos theories. Wear tests are conducted and the time series signals of frictional coefficient are collected on an MMW-1 mode friction and wear tester. The forming and disappearing process of the running-in attractor is investigated by the technique of phase-space reconstruction by time-delay. The fractal dimension of the running-in attractor is calculated and its change law is studied with correlation-dimension method. It is found that the running-in process is the forming process of the running-in attractor, the running-in attractor has a high and stable fractal dimension and a 'forming-keeping-disappearing' evolvement rule in wear process. The evolvement rule of the running-in attractor is very useful to the identification of running-in state and the prediction of wear progress.