| Running-in is a key link process in the process of manufacturing and repairing the diesel engine. A large number of theory and practice prove that Running-in is of great importance for the subsequent use of diesel engine and the running-in quality will directly affect the service life and reliability of the diesel engine. Objective and accurate extracting the characteristics in the process of diesel engine running-in and timely grasping the running-in operation state are of great significance to improve the quality of diesel engine running-in, shorten the running-in time and reduce the running-in cost.In the wear process of the cylinder liner- piston ring, friction vibration signals contain a large amount of information which reveal the state of friction pair. Therefore, the friction pair in the running-in wear process can be evaluated through the analysis of the friction vibration signals.This paper takes the cylinder liner- piston ring friction pair as the object of study, experimenting on the running-in wear process with CFT- 1 a multifunctional materials comprehensive performance tester, collecting the friction vibration signals of running-in wear process with INV- 3062T2 a signal acquisition instrument, reducing the noise from the friction vibration signals of the running-in wear process with the application of harmonic wavelets, based on which, analyzing and studying fibration signals with chaos theory. The main conclusions are as follows:(1)The research applied principal component analysis and the largest Lyapunov index to identify whether the friction vibration signals of the running-in process have chaos characteristics or not. If the principal component images of fiction vibration signals approximate linear and cross the given point with the negative slope and positive maximum Lyapunov index of friction vibration signal. Therefore, the friction vibration signals of running-in process have chaos characteristics.(2) Applying the maximum Lyapunov index and the chaotic attractor to analysis the chaos characteristics of the friction vibration signals in running-in and wear process, the results show that in the running-in process of friction pair, the maximum Lyapunov index of friction vibration signal rises gradually from 0.0019 to 0.035 at the beginning of the running-in process. After the running-in process, the friction pair starts the normal wear process in which the maximum Lyapunov index stabilizes gradually and fluctuates in 0.04. In the running-in process, the chaotic attractor fluctuates a little but shows a trend of convergence while in the normal wear process, the chaotic attractor stabilizes gradually. Therefore, the chaos characteristics, the maximum Lyapunov index and the chaotic attractor, can reflect the wear condition of friction pair in running-in and wear process.(3) Applying the maximum Lyapunov index and chaotic attractor to analysis the chaos characteristics of the friction vibration signals of dry friction process, the results show that in the dry friction process, the maximum Lyapunov index of friction vibration signals decrease gradually from 0.04 to 0.0019 and the chaotic attractor diffuses increasingly. Therefore the chaos characteristics, the maximum Lyapunov index and the chaotic attractor, can also reflect the wear condition of friction pair in dry friction process. |
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