Coupled Harmonic Balance based approach for the non-linear dynamics of spur gear pairs

Noise, Vibration and Harshness analyses are of great interest for the latest developments of the gearboxes of electric vehicles. Gearboxes are now the main source of vibrations since electric powertrains are much quieter than internal combustion engines. Traditionally, the simulation of the non-linear gears dynamics is studied by first performing a series of preliminary static analyses to compute the static transmission error (STE). The STE (i.e. in the form of varying mesh stiffness) is then accepted as the system’s excitation source to compute the dynamic transmission error (DTE). This paper presents a novel approach to analyze the non-linear dynamics of gears which does not require any preliminary static analyses. The method consists of a frequency domain approach based on the Harmonic Balance Method (HBM) and the Alternating Frequency-Time (AFT) scheme, allowing for much faster simulations when compared to the widely used direct time integration (DTI). The contact between the teeth is modeled as intermittent, penalty based with varying gap. The time varying gap between the teeth is initially approximated to a step function that guarantees the design contact ratio. The methodology introduced is tested on a lumped parameter model of a spur gear pair already proposed and simulated in the literature. The results obtained with the novel approach are compared with the DTI simulation of the model as reference. The excellent match between the different approaches validates the reliability of developed methodology