Abstract: Considering the drawbacks of existing dynamics model and analysis method of gear transmission system， the dynamic analysis method based on perfectly elastic body was presented. A certain type of marine gearbox was taken as the reserch object. Based on explicit dynamic finite element method， the 3D dynamic contact nonlinear model of housingbearinghelical gear pair system was established by considering the coupling effect between components. The dynamics characteristics on the key components were obtained by dynamically simulating the system， then compared with uncoupled model. It is shown that the stress distributions both on rolling elements and teeth surface are uneven and the coupling among the parts aggravates the impact effect in the gearbox. Finally the results are verified by Hertzian line contact theory.

Key words: coupling system, explicit dynamic, nonlinear contact force, dynamic stress