Flexible modelling of wind turbine gearboxes with special focus on shaft flexibilities

In the currently booming market of wind turbines, a clear focus is put on the design of reliable and cost-effective subsystems, such as the gearbox. A requirement for reliable gearbox design calculations is accurate load data and sufficient insight in the dynamics of the entire wind turbine drive train. To ensure this, considerable research effort is spent in advanced modelling and simulation techniques. The steadily increasing size of wind turbine gearboxes results in an increase of the influence of component flexibility. Therefore simulation models should accurately represent these. In this work the flexibile multibody modelling technique is used, as it directly includes the components’ flexibilities. A generic gearbox consisting of one planetary and two helical gear stages is modelled. A detailed estimation of the influence of the flexibility of helical gear stage shafts on the overall modal behaviour of the gearbox is discussed. The vibration modes are classified into global modes, planetary modes and helical modes. Rigid and flexible multibody models of the generic gearbox are compared. All comparisons show significant influence of the components’ flexibilities. Results are compared with results from previous work investigating the effect of flexibility on the modal behaviour of wind turbine gearboxes.status: publishe