Vibration signature analysis of commodity planetary gearboxes. (15th March 2019) - Plöger, Daniel Fritz
Highlights: Using six test specimens, a high amount of experimental data is presented. Vibration signature can be extracted using singular value decomposition. Vibration signatures of individual specimens vary considerably. Rotating lines of action explain a certain type of modulation. Abstract: Planetary gearboxes excite highly modulated vibration. From the existing literature, contradicting descriptions can be obtained. In order to resolve this situation, six commodity gearboxes are investigated on a test rig. A simple, yet powerful method to extract their vibration signatures is proposed. This novel approach consists of order tracking and singular value decomposition. The experimental data shows only partial agreement with the behavior expected from existing research. The vibration has indeed the structure of a Fourier series with respect to the angle of the planet carrier. However, the predictions concerning the most significant vibration orders made by the literature are not met. From gearboxes applied in conjunction with turbomachinery it is expected that significant vibration order can only occur at integer multiples of the number of planets. This is not met by any of the examined gearboxes. From sequentially phased automotive gearboxes it is expected that the orders below and above the nominal gear mesh order are most significant. The behavior is found in four gearboxes, but they are not sequentially phased. Mathematically it can be shown that the observed behavior is connected to forces with lines of action fixed to the planet carrier.