Topology optimization and analysis of static transmission error in lightweight gears

In this paper, the influence of gear-body lightweighting on the static transmission error (STE) for a pair of spur gears is investigated by using the Finite Element (FE) method. The transmission error, in fact, is recognized as one of the main internal excitation sources in a mechanical transmission and the minimization of its variability along the meshing cycle is considered as a design target to improve the N&V behaviour of the full transmission. The case study analysed in this paper is derived from a gearbox typically used in helicopter transmissions. The FE model of three different variants of the same gear pair, one solid model and two lightweight models, are generated and analysed by non-linear FE static simulations. By deriving the STE curves for each of the gear pairs, the impact of the increased flexibility caused by material removal in the two lightweight models is investigated.