Browse Publications Technical Papers 2019-01-0337
2019-04-02

Diagnostics of Fatigue Cracks in Rotor Systems of Machines 2019-01-0337

High-speed loaded rotor systems are widely distributed in machines and equipment of various branches of technology, including transport. Maintaining rotor systems at the appropriate high technical level is an important task, the solution of which is necessary to reduce current costs, to decrease the number of emergency situations. In this paper, the process of appearance of fatigue cracks in rotor systems is considered and the degree of their development is determined. Based on the carried out studies, the method for predicting the development of the fatigue cracks has been developed. The destruction of structural elements under variable loads usually occurs gradually, as a result of the accumulation of microdamages that pass into the developing fatigue microcracks. The appearance of cracks does not mean that the structural elements are completely out of order and that immediate repairs are necessary. In practice, structural elements with cracks can continue to function reliably for a considerable time, and a slight decrease in operating loads can increase their durability and even completely halt the growth of cracks. Therefore, when vibrating the rotor machines, it is necessary to determine not only the presence and depth of the crack, but also its location, since the rate of crack growth depends on the level of stresses arising and on the length of the present crack. Early diagnosis of the appearance of defects in these systems solves many problems. The most important element of the analysis of the state of the structure is the determination of the degree of development of the crack, the determination of the time to reach the critical size. This allows us to remove the costly risks of disturbing critical technological processes. As shown in this paper, if detection of defects is possible with the help of modal and Fourier analysis, wavelet analysis makes it possible to determine the degree of crack development over time. Using the sample of 10 experiments and calculations involving modal, Fourier and wavelet analysis of one of the rotor systems, we obtained in the paper the results allowing extending them to rotor systems of different designs.

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