Experimental and numerical investigation of fatigue failure for metro bogie cowcatchers due to modal vibration and stress induced by rail corrugation

• The high-frequency vibrations and stresses of bogie cowcatchers under rail corrugation is investigated by full-scale field test. • The resonance between the modal vibration and rail corrugation for bogie cowcatchers is found to be the main contributor to the fatigue failure. • The vehicle system dynamic model is developed and validated based on the rigid-flexible coupled dynamic theory and stress recovery approach. • Parametric studies are conducted to reveal the effects of rail grinding and structural modification on the high-frequency performance. This paper describes the high-frequency vibration fatigue failure of metro bogie cowcatchers due to short-pitch track irregularities through field testing and numerical simulations. Firstly, the dynamic stress and vibrational environment of bogie cowcatchers are investigated by full-scale testing. The acceleration spectrum density and fatigue strength of cowcatchers are evaluated. Secondly, the internal and external contributors to this issue are preliminarily analyzed through modal experiments and track irregularity measurements. Then, the rigid-flexible coupled dynamic model of the vehicle is established based on the modal synthesis method and stress recovery technique. The calculated and measured vibration and stress of the bogie cowcatchers are compared for model verification. Finally, potential solutions, i.e. rail grinding and new structure design, are proposed and verified to solve the fatigue failure issue. It is found that the modal stress at hot spot locations around the weld lines of cowcatchers can be easily excited in operations and even coincides with the frequency of the rail corrugation. One efficient treatment of this issue is the rail grinding, another one is to increase the modal frequency and eliminate stress concentration with a new structure design.