Fatigue life assessment of bogie frames in high-speed railway vehicles considering gear meshing

•A rigid-flexible coupling vehicle dynamic was established with gear meshing excitation.•Teeth backlash and time-varying sliding friction were considered into torsional vibration model.•Internal excitation from traction units was included to ensure the operation safety and reliability.•Fatigue life was significantly improved by adopting S355J2W and weld toe polishing.