An Efficient Method for Calculating Damped Critical Speeds of a Build-in Motorized Spindle
This paper presents an efficient method for calculating damped critical speeds of a build-in motorized spindle. In this method, the dynamic model of a build-in motorized spindle is established first by an improved Riccati transfer matrix method. Based on the dynamic model, the characteristic polynomial is obtained. Instead of finding all roots of the characteristic polynomial, the argument principle is used to retrieve the number of roots in the effective resonance region which is the most interested region for predicting stability. Then, the micro genetic algorithm is used iteratively to find those roots. Finally, this method is applied to calculate the damped critical speeds of a typical build-in motorized spindle supported by two identical fluid film cylindrical bearings. Numerical results indicate that the present method is efficient and effective.