Aircraft transmissions are characterized relatively low flexural natural frequencies due to their light structure and high excitation frequencies due to rotation and meshing at high operating speeds. Therefore they can be more easily subjected to some dynamic phenomena, such as travelling wave vibration (TWV) and related resonance. In spite of the fact that TWV might be a problem especially for gears having thin rim and disc, few papers can be found in the literature dealing with such a topic. This paper deals with the simulation of the vibratory behaviour of a spiral bevel gear subjected to the periodic excitation due to meshing. The investigation focused on the drive gear, the driven gear being assumed rigid. 3D FEM was used to obtain the natural modes and frequencies of the gear. Transient dynamic analysis was performed on the fixed gear simulating the rotating contact condition with respect to the gear reference system, moving the constraint around the gear. The numerical tests were performed considering a variable torque applied to the drive gear, the other being constrained, accounting for the meshing excitation. The simulation of the gear vibrations makes it possible to identify the most critical conditions for stress and fatigue in the gear body and therefore estimate the gear structural reliability.
Numerical simulation of dynamic overloads in bevel gears subjected to periodic excitation
CARMIGNANI, COSTANTINO;FORTE, PAOLA;
2009-01-01
Abstract
Aircraft transmissions are characterized relatively low flexural natural frequencies due to their light structure and high excitation frequencies due to rotation and meshing at high operating speeds. Therefore they can be more easily subjected to some dynamic phenomena, such as travelling wave vibration (TWV) and related resonance. In spite of the fact that TWV might be a problem especially for gears having thin rim and disc, few papers can be found in the literature dealing with such a topic. This paper deals with the simulation of the vibratory behaviour of a spiral bevel gear subjected to the periodic excitation due to meshing. The investigation focused on the drive gear, the driven gear being assumed rigid. 3D FEM was used to obtain the natural modes and frequencies of the gear. Transient dynamic analysis was performed on the fixed gear simulating the rotating contact condition with respect to the gear reference system, moving the constraint around the gear. The numerical tests were performed considering a variable torque applied to the drive gear, the other being constrained, accounting for the meshing excitation. The simulation of the gear vibrations makes it possible to identify the most critical conditions for stress and fatigue in the gear body and therefore estimate the gear structural reliability.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
