The transformation of experimental data from rotating frame to stationary frame

Experimental vibration data for rotating structures such as circular plates, helicopter rotors, turbine blades, bladed-disks, or propfans may be recorded either in the rotating frame or the stationary frame of reference. In the rotating frame, the sensors are mounted on the rotating structure. In the fixed frame, ground-based sensors are used, and the structure rotates past stationary sensors. Rotating sensors are commonly used in experiments, but it is sometimes desirable to transform data acquired with rotating sensors to the stationary frame. In this paper, equations for transforming experimental data such as velocity, acceleration, natural frequencies and modal damping to the fixed frame are presented. The technique may be used in situations where it is difficult or impractical to record experimental data with stationary sensors, or when a comparison with theoretical studies is required.