Considering the gearbox with an external fluid coupling

the statistical energy model is introduced based on the basic principles of statistical energy analysis.The time-varying mesh stiffness and errors are also taken into accout in calculation of gearbox noise radiation.The modal density and damping loss factor of the regular shaped subsystems are determined by using theoretical method.Meanwhile

the coupling loss factors between point junction and line junction subsystems are calculated.Each subsystem vibration response and the noise spectrum of the gearbox are obtained.The effect of the gearbox thickness

damping and bearing stiffness on the noise radiation is analyzed.An useful theoretical guideline to the design of the gearbox is provided by the study.