Abstract
The welded bogie frame is the critical safety part of the urban metro vehicle. This paper focuses on finding out the factors inducing the fatigue cracks initiated from the positioning block weld toe of metro bogie frame. Fracture morphology and metallographic analysis were conducted to identify the failure modes, and on-track tests about the dynamic stress at the positioning block weld toe and vibration acceleration were performed. The typical signals of dynamic stress and acceleration were analyzed from time and frequency domain. The relationship between wheel polygon, rail corrugation, running speed and dynamic stress in amplitude and frequency are investigated in details. Research results show that the micro cracks induced by welding at the weld toe of positioning block propagate to the spring sleeve under relatively high alternating dynamic stress, which is strongly influenced by the wheel polygon, rail corrugation and the train running speed.
Highlights
With the rapid urbanization and industrialization of China society, a huge metro rail network has been building and running in recent years
A fatigue crack in the Shinkansen train bogie frame [6] was found with a total length of 44 mm, which is regarded as a serious incident in the Japan Railway system, which could possibly have led to a derailment
A crack was found at the spring sleeve of one metro bogie frame and the service life is less than 200,000 km
Summary
With the rapid urbanization and industrialization of China society, a huge metro rail network has been building and running in recent years. As the most important load-carrying structure for railway vehicles, the welded bogie frame undergoes complex fatigue loads [1,2]. As frequently observed in metro vehicle frames, fatigue cracks are usually initiated from the welded region of the bogie frame due to complex operation loads. Such an the wheelset flexibility accelerate believed the polygonal wear and abnormal vibration [19,20] Such an irregular wheel profile could was reasonably to produce a detrimental effect on the railway axle irregular wheel profile was reasonably believed to produce a detrimental effect on the railway axle and and bogie frame [21,22,23]. Crack of finite bogie element frame [24,25], initial works been made through body dynamic system and simulations [27].
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