Analysis of the dynamic response and fatigue reliability of a full-scale carbody of a high-speed train

For a vehicle operating under different line conditions, coupled with track irregularity and many other factors, the carbody is subjected to extremely complex random loads, and the load mainly exists in the form of an alternating load; therefore, the primary type of failure is fatigue failure. With the continuous improvement in train speed, lightweight designs of carbody structures and the application of high-strength aluminium alloy, the safety and reliability of a carbody require more attention. An investigation of the dynamic fatigue reliability of a full-scale carbody of a high-speed train under random load conditions is carried out. A dynamics model of the vehicle system has been established for acquiring the time history of forces acting on the carbody by each air spring (hereinafter referred to as ‘the load–time history’). A surrogate model (a simple model instead of a complex carbody model) of the carbody is established based on the Box–Behnken matrix design and the polynomial fitting method; then, the load–time history is transformed to the stress–time history of the points of concern, and the results are compared with the results of the transient analysis, which verify the accuracy and effectiveness of the surrogate model. Then, a stress block spectrum is obtained by rain flow counting, and the stress probability distribution is determined. Combined with the probability distribution of fatigue strength, a dynamic stress–strength interference model (the area of interference between strength and stress in the model changes over time) is established. The failure rate and dynamic reliability of the points of concern for two cases are analysed: without considering the strength degradation and considering the strength degradation. The results show that without considering the strength degradation during service, with increased service mileage, the fatigue strength reliability of the points of concern decreases continuously, and the corresponding failure rate of the points of concern decreases with time and reaches a steady value, which has the characteristics of the first two stages of the bathtub curve. By considering the strength degradation during service, the reliability of the points of concern decreases gradually, and the corresponding failure rate of the points of concern decreases and then increases, with all the features of the bathtub curve. In addition, compared with the base metal region, the fatigue resistance of the welded structure decreases due to welding. Under the same service conditions, the reliability of the welded region is relatively low, and fatigue failure is more likely to occur.

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The Asymmetry of the Time History of the High-Speed Train Pass-By Noise

Acoustics Australia ◽

10.1007/s40857-015-0022-7 ◽

2015 ◽

Vol 43 (2) ◽

pp. 169-173

Author(s):

Di Wu ◽

Jianmin Ge

Keyword(s):

High Speed ◽

Time History ◽

High Speed Train ◽

History Of ◽

The Asymmetry

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Reliability Assessment of Fatigue Life of Hangers in Large-Span Suspension Bridges

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.147.149 ◽

2011 ◽

Vol 147 ◽

pp. 149-152

Author(s):

Yong Zeng ◽

Hong Mei Tan

Keyword(s):

Time History ◽

Public Confidence ◽

Suspension Bridges ◽

Fatigue Reliability ◽

Load Spectrum ◽

Accurate Analysis ◽

Vehicle Load ◽

History Of ◽

Vehicle Loads ◽

Main Cables

Hangers are very important components for suspension bridges, which link main cables and stiffening girders. When in service, hangers are much vulnerable to fatigue loads due to kinds of traffic flows, which may reduce the remaining life of the hangers and increase the risk of losing public confidence in cable supported bridges. In order to quantify the reliability of hangers under vehicle loads, fatigue reliability formula of hangers is proposed in this paper. Based on the accurate analysis of vehicle load spectrum, the time history of hangers is simulated and maintenance strategy is proposed.

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Analysis of Liquid Slug Motion in a Voided Line

Journal of Pressure Vessel Technology ◽

10.1115/1.2841889 ◽

1998 ◽

Vol 120 (1) ◽

pp. 74-80 ◽

Cited By ~ 4

Author(s):

J. Yang ◽

D. C. Wiggert

Keyword(s):

Momentum Transfer ◽

High Speed ◽

Time History ◽

Air Entrainment ◽

Phase Flow ◽

Liquid Slug ◽

Two Phase ◽

Pressure Time ◽

History Of ◽

Good Agreement

A quasi-two-dimensional two-phase flow cylindrical model of slug motion in a voided line is developed that can reasonably predict the change of flow pattern of the slug, air entrainment, “holdup” and the distribution of axial velocity. However, when using the theory of incompressible momentum transfer to estimate the pressure-time history of slug at the elbow, the calculated results are not in good agreement with those of the experiments. Further analysis of the experimental results indicate that an acoustic, or waterhammerlike response may occur immediately upon impact of the high-speed slug with the elbow, and subsequently, the waveform exhibits momentum transfer due to the acceleration of the slug at the elbow.

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On the mechanics of high speed liquid jets

Proceedings of the Royal Society of London Series A - Mathematical and Physical Sciences ◽

10.1098/rspa.1977.0160 ◽

1977 ◽

Vol 357 (1689) ◽

pp. 143-162 ◽

Cited By ~ 30

Keyword(s):

Sound Speed ◽

High Speed ◽

Supersonic Jet ◽

Time History ◽

Taylor Instability ◽

Liquid Jets ◽

Late Time ◽

History Of ◽

Theoretical Evidence

Both experimental and theoretical methods are used to investigate the mechanics of the emergence and flight of a liquid jet travelling at speeds supersonic relative to the sound speed of the liquid. The experimental work uses an Imacon image converter camera to follow the mechanical events at micro-second framing intervals. The theoretical investigation employs similarity arguments and the Tschaplygin transformation to investigate the role of liquid overcompression in the process of the jet emergence. In addition, simple theoretical arguments are used to examine the effects of Stokes drag on the small liquid particle shroud surrounding the jet and Taylor instability effects in the late time history of the jet’s flight. An evacuated chamber is used to verify the theoretical prediction that subsonic (relative to the liquid sound speed) jets will not undergo the violent decompression process predicted for supersonic jets. The experimental and theoretical evidence are synthesized into an overall picture of the jet’s history from initial decompression of an overdense supersonic jet to the breakup of the resulting liquid slugs by deceleration and Taylor instability.

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Analysis on Load Spectrum of Bogie Frame for High-Speed EMU

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.633-634.1166 ◽

2014 ◽

Vol 633-634 ◽

pp. 1166-1173

Author(s):

Yu Guang Wang ◽

Da Fu Zhang

Keyword(s):

Fatigue Life ◽

Dynamic Model ◽

High Speed ◽

Estimation Method ◽

Time History ◽

Load Spectrum ◽

Safe Operation ◽

Bogie Frame ◽

Key Factor ◽

History Of

The load spectrum, on which there is not a thorough research, is the key factor of the safe operation of EMU. A dynamic model of some high-speed EMU is established and the load time history of main load on frame is obtained through simulation and analysis based on the Beijing-Tianjin route. The load spectrum for main load is calculated by rain-flow counting, the crossing contrast of load spectrum in basic and fault conditions is proceeded as well, the extent of impact of all kinds of fault conditions to bogie main load is analyzed and a brief introduction of estimation method of the frame fatigue life is put forward in this paper.

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Multi-Objective Aerodynamic Shape Optimization of High Speed Train Nose Using Adaptive Surrogate Model

28th AIAA Applied Aerodynamics Conference ◽

10.2514/6.2010-4383 ◽

2010 ◽

Cited By ~ 8

Author(s):

V V Sunil Vytla ◽

P. Huang ◽

Ravi Penmetsa

Keyword(s):

Shape Optimization ◽

Surrogate Model ◽

High Speed ◽

High Speed Train ◽

Aerodynamic Shape Optimization ◽

Aerodynamic Shape ◽

Multi Objective

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Formulation of Reliability-Based Fatigue Assessment of a Car Body for a High Speed Train Passing Through Tunnels

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.321-323.1530 ◽

2006 ◽

Vol 321-323 ◽

pp. 1530-1534 ◽

Cited By ~ 1

Author(s):

Choo Soo Park ◽

Sung Il Seo ◽

Sung Hoon Choi ◽

Jin Yong Mok

Keyword(s):

High Speed ◽

Structural Reliability ◽

Transfer Functions ◽

Vehicle Body ◽

Railway Vehicle ◽

Distribution Characteristics ◽

High Speed Train ◽

Fatigue Reliability ◽

Car Body ◽

System Pressure

In designing the structures of railway rolling stocks, deterministic methods associated with the concept of a safety factor have been traditionally used. The deterministic approaches based on the mean values of applied loads and material properties have been used as safety verification for the design of the car body structures. The uncertainties in the applied loading for the high speed train and the strength of new materials in the structure require the application of probabilistic approaches to ensure fatigue safety in the desired system. Pressure loadings acting on the car body when the train passes through tunnels show reflected pressure waves for high-speed trains and they may cause a fatigue failure in vehicle bodies. In this paper, it is proposed that a fatigue design and assessment method based on a structural reliability that deals with the loading of pressure variations on a railway vehicle reflected in tunnels and the strength variations of material. Equation for the fatigue reliability index has been formulated to calculate the reliability assessment of a vehicle body under fluctuating pressure loadings in a tunnel. Considered in this formulation are the pressure distribution characteristics, the fatigue strength distribution characteristics, and the concept of stress-transfer functions due to the pressure loading.

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Analysis and Selection of Fluid-Film Bearings for Spool-Shaft Gas Turbines

Journal of Lubrication Technology ◽

10.1115/1.3451482 ◽

1970 ◽

Vol 92 (4) ◽

pp. 597-606

Author(s):

W. Shapiro ◽

R. Colsher ◽

O. Decker

Keyword(s):

Gas Turbines ◽

High Speed ◽

Degrees Of Freedom ◽

Ambient Pressure ◽

Time History ◽

Fluid Film ◽

Fluid Film Bearings ◽

High Speed Rotation ◽

History Of ◽

Speed Rotation

The mechanical simplicity and damping qualities of fluid-film bearings makes them attractive possibilities for spool-shaft bearings of gas turbines. The simultaneous high-speed rotation of journal and bearing, however, causes whirl stability to be a major problem. Computerized analysis was utilized to screen a spectrum of practical candidate configurations. Stability threshold plots were expeditiously generated using accurately determined cross-coupled spring and damping coefficients to represent the bearings. Performance of each bearing type was determined as a function of configuration, ambient pressure, and machined clearance. The selected three-lobe design was further tested with a “time-transient” analysis that accurately traced a complete time history of the motions of the system in its various degrees of freedom.

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Fatigue Characterization on a Cast Aluminum Beam of a High-Speed Train Through Numerical Simulation and Experiments

Chinese Journal of Mechanical Engineering ◽

10.1186/s10033-021-00628-6 ◽

2021 ◽

Vol 34 (1) ◽

Author(s):

Weiyuan Dou ◽

Lele Zhang ◽

Haifeng Chang ◽

Haifeng Zhang ◽

Changqing Liu

Keyword(s):

Finite Element ◽

Fatigue Strength ◽

Stress Concentration ◽

High Speed ◽

Fatigue Property ◽

Strength Reduction ◽

High Speed Train ◽

Cast Aluminum ◽

Structural Fatigue ◽

Aluminum Beam

AbstractThe cast aluminum beam is a key structure for carrying the body-hung traction motor of a high-speed train; its fatigue property is fundamental for predicting the residual life and service mileage of the structure. To characterize the structural fatigue property, a finite element-based method is developed to compute the stress concentration factor, which is used to obtain the structural fatigue strength reduction factors. A full-scale fatigue test on the cast aluminum beam is designed and implemented for up to ten million cycles, and the corresponding finite element model of the beam is validated using the measured data of the gauges. The results show that the maximum stress concentration occurs at the fillet of the supporting seat, where the structural fatigue strength reduction factor is 2.45 and the calculated fatigue limit is 35.4 MPa. Moreover, no surface cracks are detected using the liquid penetrant test. Both the experimental and simulation results indicate that the cast aluminum beam can satisfy the service life requirements under the designed loading conditions.

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