Dynamic imbalance of high speed planetary gears

A nonlinear 2D lumped mass model of planetary gear system with time varying mesh stiffness, bearing compliance and nonsmooth nonlinearity due to the backlash is taken into account. The time varying meshing stiffness is evaluated by means of a nonlinear finite element model, through an accurate evaluation of global and local tooth deformation. Nonlinear dynamic behaviour of the system is analyzed over a reasonable range of rotation speed and torque. Possibility of occurrences of different dynamic phenomena and instability of the system with respect to bearing compliance and operating parameters is evaluated as well. Bifurcation diagrams are extracted as well and for specific regimes, the nonlinear scenario of system is discussed using the spectra, phase portraits and Poincare maps. Periodic, quasiperiodic and chaotic regimes are found and discussed with respect to system parameters. The possibility of dynamic imbalance of equally spaced planetary gears in presence of chaotic regimes is discussed. Such imbalance may lead to unexpected high level stresses on bearings and gears.