Dynamic modeling and analysis of the planetary gear under pitching base motion

Abstract

Planetary gear transmission is subjected to base motions in many industrial applications such as wind turbines and automobiles, and its dynamic behavior will be affected by base motions. To develop a dynamic model more suitable for the planetary gear under base motions, the general modeling procedures are illustrated in detail from the perspective of energy. A rotational-translational-axial dynamic model of the planetary gear under pitching base motion is proposed and validated. Pitching base motion causes additional damping, stiffness and forced excitation, which disrupts the force symmetry of the planetary gear and results in unequal load sharing. Dynamic responses of the planetary gear are obtained by numerical integration, and spectrum analysis is conducted using the Fourier transform. Spectra of the rotational and translational vibrations of the central components show completely different characteristics because of the structure symmetry of the planetary gear. The influences rules of parameters on response spectra and load sharing conditions are derived, including the amplitude and the frequency of the pitching base motion, and the carrier rotating speed. When the base excitation frequency approaches half the translational natural frequencies, the load sharing condition of the planetary gear will deteriorate rapidly. The load sharing factor increases by the square of the base excitation amplitude.