Effect of contact ratio on dynamic behavior of a double-helical gear nonlinear system

The integrated and single tooth-meshing stiffness were calculated using tooth contact analysis and loaded tooth contact analysis with assembly misalignment. A corner meshing impact calculation model was put forward considering contact ratio, and a 12-DOF nonlinear double-helical gear vibration model was established considering meshing stiffness, corner mesh impact, and backlash. A ship transmission system was taken as an example, the proposed models were verified by changing the contact ratio. The contact ratio was changed by adjusting tooth height modification coefficients. The effectiveness of the meshing impact model was proved through comparing its calculation results with those in the literature [8]. The results showed that under the constant load, the system's vibration decreases with increase in contact ratio; however, when contact ratio exceeds 4.07, the system's vibration grows.