Methodology to Evaluate Fatigue Damage of High-Speed Train Welded Bogie Frames Based on On-Track Dynamic Stress Test Data

Abstract

The current method of estimating the fatigue life of railway structures is to calculating the equivalent stress amplitude based on the measured stress data. However, the random of the measured data is not considered. In this paper, a new method was established to compute the equivalent stress amplitude to evaluate the fatigue damage based on the measurable randomness, since the equivalent stress is the key parameter for assessment of structure fatigue life and load derivation. The equivalent stress amplitude of a high-speed train welded bogie frame was found to obey normal distribution under uniform operation route that verified by on-track dynamic stress data, and the proposed model is, in effect, an improved version of the mathematical model used to calculate the equivalent stress amplitude. The data of a long-term, on-track dynamic stress test program was analyzed to find that the normal distribution parameters of equivalent stress amplitude values differ across different operation route. Thus, the fatigue damage of the high-speed train welded bogie frame can be evaluated by the proposed method if the running schedule of the train is known a priori. The results also showed that the equivalent stress amplitude of the region connected to the power system is more random than in other regions of the bogie frame.

Effect of electromagnetic voltage on wear resistance of CrAlN coatings

“…To further confirm the fracture toughness of the coatings prepared under various electromagnetic voltages, a scratch test was carried out in a nano-scratch instrument [11]. Figure 8(c) shows the scratch morphology of the coating prepared under 25 V. The critical load L c1 of crack initiation represents the coating's ability to resist cracking [29]. Adding the electromagnetic field significantly increased the L c1 from that of the coating prepared at 0 V. The L c1 was maximized at 18.1 N under an electromagnetic voltage of 25 V.…”

Jointing Achievement and Performance Evaluation of Bogie Crossmember Ring Joint Welded via Inertia Friction Welding

“…Zhao et al [6] carried out fatigue property tests of typical welded joints and studied the effects of joint dimensions to obtain a safer S-N curve. Yang et al [7] developed a new method to calculate equivalent stress amplitudes to assess fatigue damage based on measurable randomness.…”

Extrapolation of the dynamic stress spectrum of train bogie frame based on kernel density estimation method

“…), a large number of rail vehicle structure dynamic stress collection works are small sample collections, which are completed in the short term. 4 The structural fatigue life assessment based on small sample data is equivalent to that the linear extrapolation is carried out to the small sample data. Since the simple linear extrapolation cannot fully reflect the load's random distribution characteristics and cannot predict the large load that may appear in the long-term service, the fatigue assessment results based on short term are difficult to reflect the anti-fatigue performance of the structure under long term.…”