Analysis in the time-frequency domain of different depths of a crack located in a change of section of a shaft

Detecting defects or cracks in mechanical components is essential to avoid catastrophic failures in machines. Cracks in shafts are especially delicate, because if a failure occurs, the consequences could be critical for the machine and its environment. Therefore, the development of methods that detect early defects and determine if they compromise the working of the machine is of great interest, not only from the point of view of safety, but also of design and maintenance activities. The objective of this work is to find parameters that could indicate the presence of a crack located in a change of section of a shaft with the shape of a scaled railway axle installed on a machine fault simulator. Different depths of the crack are analyzed. First, vibratory signals are measured at different rotation frequencies during the working of the shaft with and without crack using a data acquisition system. These signals are processed by means of the WPT and PSD, analyzing the first three harmonics of each rotation frequency in both cases. In this way, the best solution and the harmonics in which it is possible to detect differences between the signals coming from shafts with and without cracks are studied.