Research on dynamic characteristics and radiation noise of a helicopter main reducer based on finite element and boundary element method

In order to solve the problem of radiation noise of helicopter reducer with symmetrical structure, a simulation method is proposed to predict the noise of gearbox of a helicopter reducer from steady dynamic response to the acoustic radiation calculation. Primarily, taking the influence of time-varying stiffness into consideration, the lumped mass model of gear-rotor-bearing system is established. The dynamic load of transmission system is solved by New-Mark-& beta; method, which is regarded as excitation of the gearbox. Then finite element model of housing is established, the radiated noise of the housing is predict by finite element and boundary element method, the influence of multi-source excitation on the radiated noise of the gearbox is analyzed. Finally, the radiated noise of the reducer under different working conditions is explored. All conclusions of this research could provide theoretical reference for vibration and noise reduction of helicopter reducer.