The geometry and frequency content of planetary gear single-mode vibration

•Structured modes yield specific single-mode vibration geometry and frequency content.•Vibration in rotating and stationary frames differ in frequency content and geometry.•Different sideband frequencies occur for rotating and stationary sensors.

The geometry and frequency content of single-mode vibrations of spur planetary gears are investigated in the rotating carrier-fixed and the stationary reference frames. Planetary gears with equally spaced or diametrically opposed planets have exactly three mode types, called planet, rotational, and translational modes. The properties of these vibration modes lead to response with well-defined geometry. The frequency content of the motion differs between the rotating carrier-fixed and stationary bases. The results from this work assist the analysis of experimental planetary gear measurements.