PREDICTED AND MEASURED NATURAL FREQUENCIES OF A HIGH SPEED ROTATING SHAFT

Recently developed transfer matrix based rotating machinery vibration analysis software was tested by comparing the predicted natural frequencies of a high speed drill shaft with earlier measurements obtained by running the shaft up to 100,000 rpm. Assuming isotropic support stiffnesses at the drill shaft bearings, the first and second system natural frequency predictions were reasonably close, though because of a lack of knowledge of the support stiffnesses, perfect agreement was not to be expected. The major potential source of error in the traditional transfer matrix approach is the accumulation of round off error, and improvement to the accuracy of the predictions using the Riccati transfer matrix approach is investigated. This more accurate software produced only minor changes to the predictions.