Acoustic radiation modes and modal criterion dependency of a planetary gearbox for fault detection under the presence of tooth flank fracture

The reliability of epicyclic gearboxes is critical in today’s industrial world due to their large transmission capacity and non-linear characteristics. Epicyclic gearboxes are widely used in the automotive, aerospace and energy sectors. Condition monitoring and prognostics of epicyclic gearboxes are necessary to reduce mechanical systems’ downtime and catastrophic failures. This paper investigates computational modal analysis based on the finite element method (FEM) and experimental modal analysis (EMA) to detect and diagnose faults in epicyclic gearboxes. First, the failure-free system is modelled; second, a tooth flank fracture (TFF) is introduced to mimic a failure. The vulnerable modes of vibration are well studied. The experimental modal data acquisition has been performed using an impact hammer test to validate the results. The finite element modal analysis results and the radiation efficiency calculations show that the most vulnerable mode is the torsional mode that significantly contributes to the bearing and planet gear failure. This research adds new information to the planetary gearbox fault detection based on carrier gear torsional vibration and associated failures, as this is a matter of safety factor.