Fault Diagnosis Research About Shafting Crack Of Diesel Engine Based On Torsion Vibration Signal

Research on diesel engine shafting crack is reviewed in this paper, the importance and necessity of diagnosis for shafting crack of diesel engine is illustrated. To use the study results for reference in this paper, an analyse about similarities and differences between cracked rotor and cracked shafting of diesel engine is done. The precision time step integration method(PIM) is used for the torsion vibration numerical simulation of diesel engine cracked shafting first, and the dynamic stiffness caused by crack is analyzed.Firstly a particular analyse is given for the dynamic characters of shafting crack, an "open-and-close" function, which describes the dynamic characters of the cracked shafting of diesel engines more effectively, is put forward base on a systematically summarize and analyse for more functions which describe movement manners of cracks and their characters.Some methods for torsion vibration numerical simulation are introduced in this paper, their calculation characters are analysed and their calculation precision and stability are validated by an example, and the time step integration for the torsion vibration simulation of diesel engine shafting is set up.The two-dom and mutiply-dom equivalent systems of the diesel engine shafting are simulated by the time step integration programs which is written in Matlab software, the results of the simulation are processed by the traditional methods and the bispectrum, and the results of the signal processing are analysed.The theories and simulation are validated by a shafting vibration experimental device, the results indicate the influence mechanism of the crack mode and dynamic is correct, they also indicate the correctness of the numerical simulation for the two-dom system and the cracked shafting of diesel engines, finally we attain the torsion characters of diesel engines shafting crack fault which is used for the on-line diagnosis.