Nonlinear vibration of the axle box front cover of high-speed train and its effect on connecting bolts

Abstract

In order to explore the causes for failure of connecting bolts between the axle box front cover and axle box body on high-speed train, field test was carried out firstly in this work. The results showed that the wheel had 20th-order polygonization and the front cover vibrated drastically with the dominant frequencies of 290 Hz and 1160 Hz at the speed of 300 km/h, which were 1/2 and 2 times the rotational frequency 580 Hz of 20th-order polygonal wheel, respectively. Secondly, bench test was carried out to reproduce the unique and drastic vibration phenomenon of the field test, it was proved that the wheel polygonization took responsibility for the drastic vibration of the front cover. OMA (Operational Modal Analysis) and theoretical analysis were made next to certify existence of nonlinear vibration (subharmonic resonance of order 1/2 and superharmonic resonance of order 2) of the front cover under 20th-order polygonization. Finally, the cause of bolt failure and dynamic characteristic of the front cover resulted from different wheel polygon order was studied, results showed that relative vibration existed between axle box body and front cover. The relative vibration enlarged when the front cover was in nonlinear vibration under 20th-order wheel polygonization, which definitely caused a larger dynamic transverse load for the bolts and accelerated its vibration fatigue.