Numerical analysis of rolling contact fatigue crack initiation and fatigue life prediction of the railway crossing

Numerical Analysis of Rolling Contact Fatigue

Crack Initiation and Fatigue Life Prediction of

the Railway Crossing

Lizuo Xin, Valeri Markine (TU Delft, the Netherlands)

Ivan Shevtsov (ProRail, the Netherlands)

Outline

• Introduction

• Project overview

• Field measurements

• Finite element modeling

• Rolling contact fatigue life prediction

 Crack initiation

 Fatigue life prediction

Outline

• Introduction

• Project overview

• Field measurements

• Finite element modeling

• Rolling contact fatigue life Prediction

 Crack initiation

 Fatigue life prediction

Turnout

Reference: V.L. Markine, MJMM. Steenbergen and I.Y. Shevtsov, “Combatting RCF on switch points by tuning elastic track properties”, Wear, 2011; 271(1-2): 158-167 • Turnouts are important elements of the railway infrastructure as they provide guidance to the traffic.

A turnout consists of a switch panel, a closure panel and a crossing panel.

Crossing panel:

Research motivation

Observation from ProRail:

• Increased damage on crossings observed in Dutch railway network

• In average per week 2 crossings urgently repaired

• Annually 100 crossings replaced

• Annual replacement budget reaches €6.4million

Comprehensive approach to the problem is needed!

Typical damage on the crossing:

• Head checks • Squats • Wear • Shelling • ….

Affecting factors

Factors affecting lifetime of turnout*:

• Turnout mechanical properties

 Elasticity and damping

• Turnout geometry

 Crossing geometry in particular

 Wing rail geometry

• Wheel/rail interaction (including tribology)

• Rail material properties (hardness and toughness)

• Maintenance regime

 Welding

 Grinding

 Tamping



…

Outline

• Introduction

• Project overview

• Field measurements

• Finite element modeling

• Rolling contact fatigue life prediction

 Crack initiation

 Fatigue life prediction

Approaches

• Crossing geometry & elasticity (Manufacture & welding procedure) • Geometry

• Rail acceleration

• Rail & sleeper displacement

• Finite element (FE) modeling • Multi-body system (MBS) simulation

Field

measurements

Numerical

modeling

Evaluation & RCF

prediction

Improvement/optimization

of crossing performance

• Evaluation of new design & crossing defect

• Fatigue crack initiation & life prediction

Outline

• Introduction

• Project overview

• Field measurements

• Finite element modeling

• Rolling contact fatigue life Prediction

 Crack initiation

 Fatigue life prediction

• Conclusion & future work

Experimental analysis

•

Geometry measurements (Calipri)

 Assessment of the crossing conditions ,e.g. amount of plastic deformation  Evaluation of the geometry influence

 Input into FE model for improvement of

the crossing geometry

•

Acceleration measurements (ESAH-M)

 Obtaining distributions of maximum

accelerations (fatigue area) due to the passing wheels

 Evaluation of the wheel quality and crossing behaviour during each wheel passage, etc.  Validation of the FE model

Model validation

Comparison of the vertical accelerations of crossing under one selected wheelset

in different frequency bands

• 1:15 crossing, 135km/h

• The wheel with the smallest ratio of lateral/vertical and longitudinal/vertical accelerations

(a) measured vertical acceleration of wheelset No.24, (b-d) comparison of the vertical accelerations of the selected wheelset in different frequency bands.

Outline

• Introduction

• Project overview

• Field measurements

• Finite element modeling

• Rolling contact fatigue life Prediction

 Crack initiation

 Fatigue life prediction

September 24, 2015

Finite element modeling

Reference: Thomas Arts,Measuring the neutral temperature in railway track during installation and use Full model: length of 67.5m

Finite element modelling

• A 3D explicit dynamic finite element model to simulate the whole process of a wheelset rolling over the crossing

• Taking into account the movement of a wheelset.

• Considering crossing nose with theoretical geometry/measured geometry/imported geometry from MBS.  1:15 turnout, R=725m  S1002 wheel profile -80 -60 -40 -20 0 20 40 60 80 -60 -40 -20 0 20 40 60 z coo dina te (mm ) x coodinate (mm)

Crossing geometry & material properties

• Drawing from the manufacturer: four control cross-sections (1:15)

Top view

Side view

Front view

Material properties:

• Based on Lemaitre and Chaboche material model, to model the nonlinear material hardening.

III

II

I

-0.4 -0.2 0.0 0.2 0.4 0.6 0.8 1.0 1.2 100 200 300 400 500 600 700 Von M ises str ess ( Mp a)

Distance from the nose point (m) crossing

wing rail

 Von Mises stress in the wing rail and crossing

• Maximum Von Mises stress: P=507mm

• The most critical position (𝑃_𝑐𝑟) on the crossing!

Stress & strain responses

 Comparison of the plastic strain from the simulation and deformation from the field

• Plastic deformation with maximum value of

• Stress response

407Mpa 707MPa

695MPa 471MPa

 Von-Mises stress distribution at different positions on the crossing.

Stress & strain responses

Outline

• Introduction

• Project overview

• Field measurements

• Finite element modeling

• Rolling contact fatigue life prediction

 Crack initiation

 Fatigue life prediction

Fatigue life analysis

• Wheel/rail rolling contact problem: Multi-axial and non-proportional loading

• J-S model*: Critical plane approach for low cycle fatigue problem

• Strongly dependent on the stress state, loading histories and material type.

Critical plane: the plane with maximum

FP

value

Reference : Yanyao Jiang, Huseyin Sehitoglu,”A model for rolling contact failure”, 1999;224: 38-4

Number of cycles to crack initiation

Stress distributions at 𝑷

_𝒄𝒓

a. Maximum shear stress b. 1st_{principal stress}

c. 2nd _{principal stress} d. 3th principal stress

• It can be seen that 𝑷

most of the area in the crossing is subjected to

compressive stress due to the impact.

-8 -7 -6 -5 -4 -3 -2 -1 0 1 -1600 -1400 -1200 -1000 -800 -600 -400 -200 0 200 Stress (Mp a)

Vertical distance from rail surface (mm)

_x _y _z _xy _yz _zx -8 -7 -6 -5 -4 -3 -2 -1 0 1 -1.2E-2 -1.0E-2 -8.0E-3 -6.0E-3 -4.0E-3 -2.0E-3 0.0 2.0E-3 4.0E-3 6.0E-3 Strain

Vertical distance from rail surface (mm)

x y _z xy yz zx

Stress (a) and strain (b) components of the elements at different vertical positions

• At 𝑷

, the stress and strain components at five points are plotted. The

vertical position of these points are:



V

=0mm, V

=1.316mm, V

=2.606mm, V

=3.994mm, V

=7.006mm

• The selected points are in both compressive area and tensile/compressive

area

Fatigue life analysis of 𝑷

_𝒄𝒓

Vertical distance from rail surface (mm)

 

• Fatigue analysis of 𝑷

was conducted on the five selected points

 V0=0mm, V1=1.316mm, V2=2.606mm, V3=3.994mm, V4=7.006mm

Angles of the critical planes.

*𝜃 and 𝜑 represent the spherical angles of the normal vector of the critical plane to the coordinates system attached to the railhead surface.

z

x

𝜑

y

𝜃

o

o

(a). Vertical-longitudinal view (b). Lateral-longitudinal view

Fatigue life analysis of 𝑷

_𝒄𝒓

Number of cycle to fatigue, Nf Nf

21004

Number of cycles to fatigue crack initiation

• Fatigue analysis of 𝑷

was conducted on the five selected points

0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 1.1 0.0140 0.0145 0.0150 0.0155 0.0160 0.0165 0.0170 0.0175

Distance from the nose point (m)

La ter al d istan ce f ro m in ne r sid e o f cr ossing (m ) Coordinates (y,z) Nf 103 104 105 106 107 108 21707153 4975980 199062 21004 N f 6501922

• The critical points of five contact positions (P

, P

to P

) on the

crossing are selected.

Fatigue life analysis of the whole crossing

0.4 0.5 0.6 0.7 0.8 0.9 1.0 1.1 0 20 40 60 80 100 120 140 160 Critical p lane an gle (°)

Distance from the nose point (m)

 

(a) Angles of the critical planes (b). Number of cycles to fatigue crack initiation

P_cr1 P_cr2 P_cr3 P_cr4 P_cr5

𝑷

= 𝟓𝟎𝟕𝒎𝒎

Conclusion

• A numerical procedure is developed to predict the rolling contact fatigue crack initiation in the crossing. The dynamic responses of the crossing such as stress and strain results are obtained from the FE simulation. Jiang and Sehitoglu fatigue model is then employed for prediction of fatigue life.

• The angles of crack planes as well as the fatigue life of the crossing are obtained, according to different depth and different contact positions in the crossing.

• For rolling contact fatigue problem the weakest position of the crossing is always the position of impact. High impact force leads to high stress and plastic strain, which ultimately determine the minimum fatigue life of the crossing.

• Validation with field measurements

Future work

• Fatigue analysis at more positions on the crossing nose

• Cyclic loading and ratchetting behaviour • Combined with specific loading conditions

Thanks for your attention!

Lizuo Xin