Friction Analysis of an Unbalanced Disk with Recurrence Plot by Using Simpson Integration and Empirical Mode Decomposition

The most common failures that raise vibration levels in rotating machines are friction and unbalanced faults of their components. This kind of fault affects severely the reliability of the equipment and the service life of machines. There are numerous publications on the various techniques used to diagnose friction and unbalanced faults, and some of them are focused on resolving the problem to transform the vibration taken by an accelerometer into velocity and displacement to completely characterize the movement of rotating components. In this paper, the Recurrence Plot (RP) is proposed to analyze dry friction on mechanical rotating systems, and Simpson’s rule with Empirical Mode Decomposition (EMD) is implemented to integrate the acceleration to compute the velocity and displacement which are needed for RP construction. To analyze dry friction an experiment is implemented with an unbalanced disk mounted on a flexible shaft and a friction point on its outer diameter. Vibrations are obtained by an accelerometer fixed on one support and with a vibrometer pointed near the contact surface point of the disk. This work aimed to address the suitability of RP for the analysis of a typical nonlinear friction phenomenon of an unbalanced disk. The RP was computed and compared at different speeds by using both instruments while keeping the unbalanced test mass constant. The results indicated that the RP patterns show significant differences when the friction load is applied but only some of the quantification parameters reflect these differences.