Modal analysis is based on the static finite element model. In the process of modal analysis, the natural characteristics (natural frequency and natural mode) of the system are solved, which are independent of the external forces, and the effect of external loads can be ignored; moreover, in the process of calculating the natural characteristics of the structure, the damping has little effect on it, and the damping term can be omitted.
The mode shape is the torsion, bending and deformation of the system under a certain excitation frequency. By analyzing the characteristics and amplitudes of vibration modes, we can find the reasons of high dynamic response amplitudes and large modal flexibility, and can correspond to a certain component.
Because the transmission has multiple gears, it has different modal characteristics when different gears are combined. In this paper, the first nine modal features with the largest modal flexibility are extracted from the modal shape of the second gear.