Dynamic Analysis Of CRH2 Emu Using Wheel Flat Models Describing Wheel Tread Out-of-round Damage

Wheel tread geometrical damage is an inevitable phenomenon for railway vehicles in service.Wheel flat is an abstract damage model with an additional extreme vertical excitation between wheel-rail to the damages with the same circular scale on wheel tread.Three pieces of research work are performed to address on the wheel tread damage and operational management policy of CRH2 type EMUs:(1)Field investigations were carried out on wheel damaged modes and their measuring geometries of the EMUs.Construct approaches and differences of the present flat model from the product damage modes were presented and discussed.(2)Dynamic performances of the EMUs were carried out by the coupled dynamic model of the wheel-rail system under considering the elastoplastic constitutive relations of wheel and axle materials.Results show that significant higher dynamic responses are obtained for the case without considering the elastoplasticity.It is necessary to consider the elastoplasticity in the assessment on the dynamic performances to hold true vehicle behavior.(3)Manage policy is suggested for the EMUs when the wheel tread appears geometrical damages in production.This policy is decided from considerations of allowable vertical contact force.Results reveal that when the flat length is less than 20 mm and the EMUs can run at a commercial speed and a limit should be followed when the size over the scale.The present work provides a product guidance for assuring the EMUs running under a good state with better dynamic performance.