In modern society, it is an important problem to condition monitoring and fault diagnosis of mechanical equipment and has being paid more and more attention to, for it has great economy and project value. In recent years, many scholars have made a lot of job on it, and put up some new methods of fault diagnosis. As an important part of mechanical equipment, the diesel’s state control and fault diagnosis have momentous signification, for it’s widely used. In this paper, in order to analyze the signal gained from diesel engine, fractal is adopted. Characteristic information for faults is gained from diesel engine vibration signal by using new method adapting to analyze non-stationary signal on the basis of former achievements, and valid results are obtained. The fractal dimension is compared between normal condition and fault condition of the diesel.First, a data collecting software for diesel engine vibration based on VB is developed after the hardware system has been jointed and accomplished. The software can collect the diesel engine vibration signal with different channels, different kinds of frequency and different kind of gains; it also can save the data files with different formats. Besides the data collecting function, the software can analyze the data files based on fractal. The software also can be used as a diesel engine vibration real-time monitoring system, it can display the vibration wave when the diesel is working, analyze the real-time vibration data, and print the analyze results in reports forms.Then, from the starting point of vibration signals formed, the characteristics of actuation sources and their responses and the relations between them are discussed in detail. Meanwhile, radiate routes of vibration signals are analyzed, and pretreatment methods for vibration signals are presented. The results show that it is effective and feasible to diagnose faults of diesel engine by mean of un-disassembly using surface vibration signal.In succession, fractal is imported especially for solving questions about nonlinearand non-stationary of diesel surface vibration signals. A formula with variation has been set to calculate the fractal dimension of the vibration curve. Through the comparison of the vibration signals between the normal condition and three fault conditions, it has been discovered that the vibration signals from fault conditions is more complex and more unregulated than that from normal condition. And the obvious increasing trend of the fractal dimension shows that using fractal dimension to sign the diesel engine vibration is available, the result means it is effective and feasible to diagnose faults of diesel engine by mean of un-disassembly using fractal.At last, this paper illustrates the shortage of fault diagnosis using fractal and some parts of the software needed to add in, and gives some suggestion for the study on this topic in the future.
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