Numerical investigation of the fatigue performance of elastic rail clips considering rail corrugation and dynamic axle load

2020 ◽  
pp. 095440972092601
Author(s):  
Ping Wang ◽  
Jun Lu ◽  
Caiyou Zhao ◽  
Mingming Chen ◽  
Mengting Xing
Keyword(s):  
Fatigue Life ◽  
Stress Amplitude ◽  
Cyclic Stress ◽  
Maximum Speed ◽  
Analysis Method ◽  
Vibration Acceleration ◽  
Intrinsic Frequency ◽  
Rail Corrugation ◽  
Naturally Occurring ◽  
Coupling Dynamic

To analyze the reasons for rail clip fracture, the characteristics of rail corrugation were first measured using a rail corrugation meter. The vibration acceleration of the fastener clips at the sections with/without rail corrugation was measured, and the effects of rail corrugation on the clip vibration were analyzed. After this, a vehicle--track coupling dynamic model and a refined model for the fastener system were established in order to study the effects of rail corrugation on the vibration acceleration and stress on critical points. Finally, the rail grinding limits were determined based on the fatigue analysis method and the damage accumulation theory from the aspect of the fatigue life of the clip. The results of the study showed that the main wavelength of rail corrugation at the rail clip fracture section was approximately 40 mm. The vibration acceleration of the clip caused by rail corrugation was too large. Under normal installation conditions, the maximum clip stress was 1490 MPa at the small circular arc on the rear arch, which was identical to the on-site fracture location. The intrinsic frequency of the clip was approximately 810 Hz. Rail corrugation excited and triggered the forced vibration of the clip, and induced resonance at a speed of 120 km/h and a wavelength of 40 mm. The large cyclic stress amplitude of the clip with rail corrugation increased from 44 MPa to 68 MPa when compared with the clip without rail corrugation. Rail clip fracture was caused by the naturally occurring resonance fatigue arising from rail corrugation. For metro lines designed with a maximum speed of 120 km/h, it was suggested to control the rail corrugation amplitudes with a wavelength of 40 mm, 50 mm, 30 mm, 120 mm and 160 mm to below 0.04, 0.08, 0.16, 0.19 and 0.2 mm, respectively, taking into account the fatigue life of the clip.

A Statistically Load-Weighted Probabilistic Fatigue Life Model

2008 ◽  
Vol 44-46 ◽  
pp. 51-56 ◽  
Author(s):  
Li Yang Xie ◽  
Wen Qiang Lin
Keyword(s):  
Fatigue Life ◽  
Stress Amplitude ◽  
Random Variable ◽  
Cyclic Stress ◽  
General Situation ◽  
Statistical Average ◽  
Underlying Principle ◽  
Model Configuration ◽  
System Of Units ◽  
Life Model

By interpreting traditional stress-strength interference model as a statistical average of the probability that strength (a random variable) is greater than stress (another random variable) over its whole distribution range, the same model configuration, which was conventionally applied only to the case of same system-of-units parameters (e.g., stress and strength, both are measured in MPa), was applied to more general situation of different system-of-units parameters. That is to say, the traditional model was extended to more general situations of any two variables, as long as one of the variables can be expressed as a function of the other. Further more, the probabilistic fatigue life under random stress can be predicted, with known probabilistic fatigue lives under several deterministic cyclic stress amplitudes and known distribution of the random cyclic stress amplitude. The underlying principle is that the fatigue life under random stress is equal to the statistical average of the fatigue lives under cyclic stress of deterministic amplitudes which can be considered as the samples of the random stress.

scholarly journals Analysis on the Effects of Material Parameters on the Fatigue Performance of Novel Anticorrugation Elastic Rail Clips

2020 ◽  
Vol 2020 ◽  
pp. 1-11
Author(s):  
Ping Wang ◽  
Jun Lu ◽  
Caiyou Zhao ◽  
Li Yao ◽  
Xuanhui Ming
Keyword(s):  
Plastic Deformation ◽  
Fatigue Life ◽  
Natural Frequency ◽  
Coupling Model ◽  
Dynamic Responses ◽  
Clamping Force ◽  
Vibration Acceleration ◽  
Rail Corrugation ◽  
Material Parameters ◽  
Selection Of

A novel elastic rail clip was obtained through size improvement based on the II-type elastic rail clips to solve the fatigue failure of elastic rail clips. The metro vehicle-track coupling model and the fastener system refinement model were developed to analyze the effects of the material (38Si7 and 60Si2Mn) on the static and dynamic responses of the elastic rail clips and their fatigue performances under rail corrugation. According to the results, the elastic rail clip made of 60Si2Mn did not undergo any plastic deformation and exhibited higher strength than that made of 38Si7. Elastic rail clips made of 38Si7 and 60Si2Mn presented a consistent clamping force, natural frequency, and vibration acceleration. However, they were most sensitive to the wavelength of 50 mm. Both materials influenced the small back bending area of the elastic rail clip only. The elastic rail clip made of 60Si2Mn could meet the fatigue life requirements of 5 million times. As for the elastic rail clip made of 38Si7, the corresponding values of corrugation with the wavelength of 50 mm and 40 mm are to be controlled below 0.09 mm and 0.41 mm, respectively. The performance of the elastic rail clips to resist rail corrugation can be improved significantly through the increase in the geometric dimensions and selection of materials with higher strength.

A Theoretical Study on the Cables Fatigue Life Quantitative Analysis Method of Cable Bridges

2014 ◽  
Vol 501-504 ◽  
pp. 1214-1220
Author(s):  
Fang Yu ◽  
Lie Ping Ye ◽  
Zhi Jun Dong
Keyword(s):  
Fatigue Life ◽  
Quantitative Analysis ◽  
Fatigue Strength ◽  
Stress Amplitude ◽  
Nominal Stress ◽  
Analysis Method ◽  
Analysis Theory ◽  
Quantitative Analysis Method ◽  
Stress Fatigue ◽  
External Loads

Based on the theory of fatigue fracture of metals, quantitative analysis method was proposed for fatigue strength of cables of cable bridges and conclusions were reached through analysis of calculation formula: the analysis method of stress fatigue life was able to consider the section dimensions of the cables, plasticity of the material and stress ration caused by external loads and other factors which affect the fatigue life. This analysis theory was correct which took into consideration of relatively overall factors and was a better way to analyze the cable fatigue life. Meanwhile, the design of fatigue strength of bridge cables should adopt the theoretical fatigue limit represented by equivalent nominal stress amplitude as the design value of fatigue strength of cable. The theory represented by equivalent nominal stress amplitude considered the influence of stress ratio on fatigue life of cables caused by external loads. Compared with traditional method of fatigue strength estimate, with sufficient theory basis and overall consideration of factors, the results of this method were more reliable.

Fretting fatigue behavior and failure characteristics of 35CrMoA steel under elliptical loading path

2021 ◽  
Vol 73 (6) ◽  
pp. 922-928
Author(s):  
Ziao Huang ◽  
Xiaoshan Liu ◽  
Guoqiu He ◽  
Zhiqiang Zhou ◽  
Bin Ge ◽  
...  
Keyword(s):  
Fatigue Life ◽  
Contact Pressure ◽  
Wear Debris ◽  
Stress Amplitude ◽  
Fatigue Behavior ◽  
Fretting Fatigue ◽  
Cyclic Stress ◽  
Loading Path ◽  
Fatigue Wear ◽  
Content Type

Purpose This study aims to understand the multiaxial fretting fatigue, wear and fracture characteristics of 35CrMoA steel under the elliptical loading path. Design/methodology/approach By keeping the contact pressure and torsional shear cyclic stress amplitude unchanged; the axial cyclic stress amplitude varied from 650 MPa to 850 MPa. The fretting fatigue test was carried out on MTS809 testing machine, and the axial cyclic strain response and fatigue life of the material were analyzed. The fretting zone and fracture surface morphology were observed by scanning electron microscope. The composition of wear debris was detected by energy dispersive X-ray spectrometer. Findings In this study, with the increase of axial stress amplitude, 35CrMoA steel will be continuously softened, and the cyclic softening degree increases. The fretting fatigue life decreases unevenly. The fretting scars in the stick region are elongated in the axial direction. The area of fracture crack propagation zone decreases. In addition, the results indicate that wear debris in the slip region is spherical and has higher oxygen content. Originality/value There were few literatures about the multiaxial fretting fatigue behavior of 35CrMoA steel, and most scholars focused on the contact pressure. This paper reveals the effect of axial cyclic stress on fretting fatigue and wear of 35CrMoA steel under the elliptical loading path.

The High Cycle Fatigue and Fracture Behavior of Friction Stir Welded Aluminum Alloy 2024

2008 ◽  
Vol 378-379 ◽  
pp. 175-206 ◽  
Author(s):  
T.S. Srivatsan ◽  
Satish Vasudevan ◽  
Lisa Park ◽  
R.J. Lederich
Keyword(s):  
Fatigue Life ◽  
Fracture Behavior ◽  
High Cycle Fatigue ◽  
Stress Amplitude ◽  
Tensile Ductility ◽  
Cyclic Stress ◽  
Cycle Fatigue ◽  
Friction Stir ◽  
Final Fracture ◽  
Microstructural Effects

In this research paper, the cyclic stress amplitude controlled fatigue response and fracture behavior of an Al-Cu-Mg alloy (Aluminum Association designation 2024) is presented and discussed. The alloy was friction stir welded in the T8 temper to provide two plates one having high tensile ductility and denoted as Plate A and the other having low tensile ductility and denoted as Plate B. Test specimens of the alloy, prepared from the two plates, were cyclically deformed under stress amplitude control at two different load ratios with the primary objective of documenting the conjoint influence of magnitude of cyclic stress, load ratio and intrinsic microstructural effects on cyclic fatigue life and final fracture characteristics. The high cycle fatigue resistance of the alloy is described in terms of maximum stress, R-ratio, and microstructural influences on strength. The final fracture behavior of the friction stir welded alloy is discussed in light of the concurrent and mutually interactive influences of intrinsic microstructural effects, deformation characteristics of the alloy microstructure, magnitude of cyclic stress, and resultant fatigue life.

Effect of Contact Pressure and Cyclic Stress Amplitude on Fretting Fatigue of 45-Carbon Steel

2007 ◽  
Vol 353-358 ◽  
pp. 134-137
Author(s):  
Wei Ming Sun ◽  
Shui Sheng Chen ◽  
Li Qun Tu
Keyword(s):  
Fatigue Life ◽  
Carbon Steel ◽  
Contact Pressure ◽  
Main Crack ◽  
Stress Amplitude ◽  
Fretting Fatigue ◽  
Cyclic Stress ◽  
Outer Edge ◽  
Middle Portion ◽  
Contact Pressures

The effect of contact pressure on fretting fatigue in quenched and tempered 45-carbon steel is studied. With an increase in contact pressure, fretting fatigue life is decreased quickly at low contact pressures; however it almost unchanged at high contact pressures. With an increase in cyclic stress amplitude, fretting fatigue life decreased. In the test, concavity is formed at the fretted area accompanying wear. The main crack is initiated at the outer edge corner of the concavity at high contact pressures, and initiated at the middle portion of the fretted area at low contact pressures.

An Investigation of the Cyclic Fatigue and Final Fracture Behavior of a Titanium Alloy

2008 ◽  
Vol 378-379 ◽  
pp. 271-298 ◽  
Author(s):  
T.S. Srivatsan ◽  
Mithun Kuruvilla ◽  
Lisa Park
Keyword(s):  
Titanium Alloy ◽  
Fatigue Life ◽  
Fracture Behavior ◽  
Stress Amplitude ◽  
Load Ratio ◽  
Cyclic Fatigue ◽  
Cyclic Stress ◽  
Fatigue Properties ◽  
Final Fracture ◽  
Stress Load

In this technical manuscript the cyclic stress amplitude controlled fatigue properties and fracture behavior of an emerging titanium alloy (referred to by its designation as ATI 425TM by the manufacturer) is presented and discussed. The alloy was provided as rod stock in the fully annealed condition. Test specimens of the as-received alloy were cyclically deformed under total stress amplitude control at two different stress ratios (R = 0.1 and R = 0.3) with the purpose of establishing the conjoint and mutually interactive influences of magnitude of cyclic stress, load ratio and intrinsic microstructural effects on cyclic fatigue life, final fracture behavior and viable mechanisms governing failure at the microscopic level. The high cycle fatigue resistance of this titanium alloy is described in terms of maximum stress, load ratio, and maximum elastic strain. The final fracture behavior of the alloy under cyclic loading conditions is discussed in light of the mutually interactive influences of intrinsic microstructural features, magnitude of cyclic stress, load ratio and resultant fatigue life.

An Investigation of the High Cycle Fatigue and Final Fracture Behavior of Aluminum Alloy 2219

2008 ◽  
Vol 378-379 ◽  
pp. 207-230 ◽  
Author(s):  
T.S. Srivatsan ◽  
Satish Vasudevan ◽  
Lisa Park ◽  
R.J. Lederich
Keyword(s):  
Fatigue Life ◽  
Fracture Behavior ◽  
High Cycle Fatigue ◽  
Stress Amplitude ◽  
Load Ratio ◽  
Cyclic Stress ◽  
Cycle Fatigue ◽  
Final Fracture ◽  
Stress Load ◽  
Microstructural Effects

In this research paper, the cyclic stress amplitude controlled fatigue response and fracture behavior of an Al-Cu (Aluminum Association designation 2219) is presented and discussed. The alloy was provided as a thin sheet in the T62 temper in the fully anodized condition. A small quantity of the as-provided sheet was taken and the surface carefully prepared to remove the thin layer of anodized coating. Test specimens of the alloy, prepared from the two sheets (anodized and non-anodized), were cyclically deformed under stress amplitude control at two different load ratios with the primary objective of establishing the conjoint influence of magnitude of cyclic stress, load ratio and intrinsic microstructural effects on cyclic fatigue life and final fracture characteristics. The high cycle fatigue resistance of the alloy is described in terms of maximum stress, load ratio, and microstructural influences on strength. The final fracture behavior of the alloy sheet is discussed in light of the concurrent and mutually interactive influences of intrinsic microstructural effects, deformation characteristics of the alloy microstructure, magnitude of cyclic stress, and resultant fatigue life.

Fatigue Life of the Human Teeth: A Continuum Damage Approach

2019 ◽  
Vol 43 ◽  
pp. 1-19
Author(s):  
Theddeus Tochukwu Akano
Keyword(s):  
Fatigue Life ◽  
Damage Mechanics ◽  
Stress Amplitude ◽  
Continuum Damage Mechanics ◽  
Continuum Damage ◽  
Elastoplastic Model ◽  
Human Teeth ◽  
Proposed Model ◽  
Number Of Cycles ◽  
Cycles To Failure

Normal oral food ingestion processes such as mastication would not have been possible without the teeth. The human teeth are subjected to many cyclic loadings per day. This, in turn, exerts forces on the teeth just like an engineering material undergoing the same cyclic loading. Over a period, there will be the creation of microcracks on the teeth that might not be visible ab initio. The constant formation of these microcracks weakens the teeth structure and foundation that result in its fracture. Therefore, the need to predict the fatigue life for human teeth is essential. In this paper, a continuum damage mechanics (CDM) based model is employed to evaluate the fatigue life of the human teeth. The material characteristic of the teeth is captured within the framework of the elastoplastic model. By applying the damage evolution equivalence, a mathematical formula is developed that describes the fatigue life in terms of the stress amplitude. Existing experimental data served as a guide as to the completeness of the proposed model. Results as a function of age and tubule orientation are presented. The outcomes produced by the current study have substantial agreement with the experimental results when plotted on the same axes. There is a notable difference in the number of cycles to failure as the tubule orientation increases. It is also revealed that the developed model could forecast for any tubule orientation and be adopted for both young and old teeth.

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