Effect of sliding friction on torsional vibration of wind turbine drivetrain system under constant wind load

Sliding friction is an unavoidable phenomenon that occurs between two contacting bodies under motion. In this paper, dynamic analysis of wind turbine drivetrain system (WTDS) is performed and sliding friction is incorporated in the model. Key tooth meshing points along path of contact like pitch point, single and double pair region are identified; reversal of force due to sliding friction at pitch point is explained. The drivetrain system contains three stages of gear drive. To study the dynamic characteristics of the system, governing equations of motion of lumped parameter model is derived using Lagrange's formulation. Time varying mesh stiffness (TVMS) is estimated using the analytical method and frictional torque are incorporated in the drivetrain model. Finally, the governing equations are numerically solved using the Houbolt discretisation method in MatLab. Torsional vibration signals and frictional torque are obtained in MatLab. The simulation results with and without friction are fast Fourier transformed. The dynamic effect of sliding friction on the WTDS is investigated in the frequency domain and comparison is made with no friction condition.