Long-term prediction of fatigue crack growth in ballastless track of high-speed railway due to cyclic train load

2021 ◽  
Vol 292 ◽  
pp. 123375
Author(s):  
Qingsong Feng ◽  
Kui Sun ◽  
Hua-Peng Chen ◽  
Xiaoyan Lei
2017 ◽  
Vol 185 ◽  
pp. 160-174 ◽  
Author(s):  
Grzegorz Lesiuk ◽  
Mieczysław Szata ◽  
José A.F.O. Correia ◽  
A.M.P. De Jesus ◽  
Filippo Berto

Author(s):  
Masaru Sekihara ◽  
Shigeo Sakurai

The effects of mechanical degradation on the creep- and fatigue-crack growth rates in power plants operated long-term were studied. Creep-crack growth tests and fatigue-crack growth tests were performed using creep-pre-strained and repetitive-strained CrMoV rotor-steel specimens. It was found that the creep-crack growth rates, da/dt, of the creep-pre-damaged specimens were larger than those of virgin specimens under constant load. It was also found that under the same stress intensity factor K, da/dt in the case of about 10%-crept and creep void induced specimens was increased five times, while in the case of 0.8%- and 2.8%-crept specimens, it only increased a little. However, all the data fell in a narrow scatter band in the relationship between C* and da/dt. The effect of long-term operating degradation appeared on the creep- and fatigue-damage under the Slow-Fast waveform. Also the crack density was larger in the damaged specimens compared with the virgin specimens. Other results showed that the fatigue-crack growth rates, da/dN, of creep- and fatigue-pre-damaged specimens were larger than those of virgin specimens. Under the same stress intensity factor range ΔK, da/dN in a specimen with approximately 10%-creep was increased 20 times. Moreover da/dN in fatigue-pre-damaged specimens was accelerated 10 times. However, the results of the strain-controlled crack growth test fell in a narrow scatter band in the relationship between J integral range ΔJ and da/dN. These results suggest that the creep remaining lives and fatigue remaining lives of mechanically damaged CrMoV steel can be estimated using the C* & ΔJ values considering the creep rate and the deformation rate of the pre-damaged materials and the da/dt and da/dN values of the virgin material.


2020 ◽  
Vol 28 (3) ◽  
pp. 213-231
Author(s):  
Wanming Zhai ◽  
Kaiyun Wang ◽  
Zhaowei Chen ◽  
Shengyang Zhu ◽  
Chengbiao Cai ◽  
...  

Abstract Motivated by the huge practical engineering demand for the fundamental understanding of mechanical characteristics of high-speed railway infrastructure, a full-scale multi-functional test platform for high-speed railway track–subgrade system is developed in this paper, and its main functions for investigating the mechanical performance of track–subgrade systems are elaborated with three typical experimental examples. Comprising the full-scale subgrade structure and all the five types of track structures adopted in Chinese high-speed railways, namely the CRTS I, the CRTS II and the CRTS III ballastless tracks, the double-block ballastless track and the ballasted track, the test platform is established strictly according to the construction standard of Chinese high-speed railways. Three kinds of effective loading methods are employed, including the real bogie loading, multi-point loading and the impact loading. Various types of sensors are adopted in different components of the five types of track–subgrade systems to measure the displacement, acceleration, pressure, structural strain and deformation, etc. Utilizing this test platform, both dynamic characteristics and long-term performance evolution of high-speed railway track–subgrade systems can be investigated, being able to satisfy the actual demand for large-scale operation of Chinese high-speed railways. As examples, three typical experimental studies are presented to elucidate the comprehensive functionalities of the full-scale multi-functional test platform for exploring the dynamic performance and its long-term evolution of ballastless track systems and for studying the long-term accumulative settlement of the ballasted track–subgrade system in high-speed railways. Some interesting phenomena and meaningful results are captured by the developed test platform, which provide a useful guidance for the scientific operation and maintenance of high-speed railway infrastructure.


2004 ◽  
Vol 261-263 ◽  
pp. 1037-1042 ◽  
Author(s):  
Sung Jae Kwon ◽  
Kazuhiro Ogawa ◽  
Tetsuo Shoji

The fracture mechanics characteristics in the critical locations of the wheelset for high-speed train have not been studied enough yet despite of severe conditions due to increase in operating speeds. Moreover, the fracture mechanics characteristics with respect to the aging effects of wheelset materials have not been clearly studied. In the present study, the following fracture mechanics characterization tests were carried out in accordance with various locations on the wheelset for high-speed train: fracture toughness depending on load rate, fatigue crack growth rate and fatigue thresholds. The results show that the fatigue crack growth rates in accordance to the locations on wheelset were not remarkably different, and the fatigue threshold in the region of the bolt-hole is lower than that in other regions. The fracture toughness depending on load rate data shows that once the downward curve from quasi-static values was reached, subsequent values showed a slow increase with respect to the impact velocity. This means that dynamic fracture toughness should be considered in the design code of the wheelset material.


2016 ◽  
Vol 160 ◽  
pp. 262-269 ◽  
Author(s):  
G. Lesiuk ◽  
P. Kucharski ◽  
J.A.F.O. Correia ◽  
A.M.P. De Jesus ◽  
C. Rebelo ◽  
...  

Sign in / Sign up

Export Citation Format

Share Document