Rail Wheel 1

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Date-19-March-2010

STATIC ANALYSIS OF RAIL ROAD WHEEL


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Contents Page No

1. Objective 1

2. Geometry Details 2

3. Materials&Properties 3

4. Description 4

5. FEA model 5

6. Boundary Conditions 6

7. Results 7

8. Conclusion 8


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Modulus of elasticity 206000 MPa Tensile yield stress (0.2% offset 761 MPaCyclic yield stress (0.2% offset) 580 MPaUltimate tensile stress 781 MPa\

True fracture stress 647 MPa

4. Description FEA functionality

Fig.2The functionality of FEA will be as shown in Fig.1.Analyst need to take the feed

back from the initial design parameters and can asses the new proerties.To get theoptimized design one should carry multiple no of analyses. This analysis mainlycarries totally four cases, for two different materials. Design feed back may be atany stage, like geometry, material and loading conditions. Here it is mainlyconsidered material as the key parameter

Methodology:A railroad wheel is usually rigidly mounted on a steel shaft. Due to the high axleload and small contact area of the wheel/rail interface, the stresses at contactregion are very high. To overcome the limitations of the traditional approaches for the wheel/rail contact problem, a 3D elasto-plastic finite element model is needed.After comparing several possible approaches, a simulation methodology for wheel/rail contact analysis is proposed in this analysis. 3D finite element modeland can accurately calculate the 3D stress response in the contact region. Next, itincludes both material and geometric nonlinearity. It can be used to simulate largeand complex wheel motions. Different meshing is applied to the full model using3D element (SOLID 45 in ANSYS). In the contact region, relatively finer mesh isused. At the wheel center, a pilot point is connected to the wheel using some rigidlink elements. All the external loading and boundary conditions of the wheel are


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applied on the pilot point. On the possible contact areas of the railhead and thewheel tread, area contact elements (CONTACT 174 and TARGET 170 inANSYS)are used corresponding to the geometry mesh of the wheel. The contact algorithmis augmented Lagrangian method. Friction effect (0.3) is included into the material

properties of the contact element. The elements used for analysis is shown below

Elements usedComponent Name Type No of elementsWheel Solid92 3-d-Tetreahedral 131434Rail Solid92 3-d-Tetreahedral 5000Contact Inter face onWheel Conact174 2-d-Triangular 600Contact Inter face on Rail Target170 2-d-Triangular 600For Load application Rigids(Cerig) 1-d-Cerig 1Dummy Mass Mass21 0-d 1

Table-3

About Element:

SOLID92- 3-D 10-Node Tetrahedral Structural Solid

SOLID92 Element Description

SOLID92 has a quadratic displacement behavior and is well suited to model

irregular meshes (such as produced from various CAD/CAM systems). Theelement is defined by ten nodes having three degrees of freedom at each node:translations in the nodal x, y, and z directions. The element also has plasticity,creep, swelling, stress stiffening, large deflection, and large strain capabilities

Element Features:

Nodes I, J, K, L, M, N, O, P, Q, R Degrees of Freedom UX, UY, UZSpecial Features Plasticity, Creep, Swelling, Stress stiffening, large deflection,large strain


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Figure 3 SOLID92 Geometry

5- FEA-Model and boundary conditions:

FIG: 4


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Loading Details-

There are mainly two loads considered in this analysis. Two loads applied on the Wheelcomponent through a pilot mass element. Given loadings per axle are

Load 1-200(kN)

Load 2-1.53*200(kN)

Load 3-2.0*200 (kN)

Load 4-2.5*200(kN)

As there is symmetry existed in the model it is considered that the load get shared by twowheels. The magnitude of load will get halved.

Assumptions-

Contact surface considered as rigid homogeneous material.Loadings considered that acing on axle as concentrated load.Design temperature taken as room temperature

Fig:5


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1. Material IS 228 Case:1- Results

Vonmises Stress plot (Mpa)

Shear stress ( xy)(Mpa)

7-Results


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Shear stress( y z)(Mpa)

Resultant Deformation (Usum)(mm)


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Contact Pressure (Mpa)

2. Material IS 228 Case:2-Results



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Shear stress ( xz)(Mpa)


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Shear stress ( xz)(Mpa)



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Shear stress ( y z)(Mpa)


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5. Material SAE 1045steel Case:1-Results




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Shear stress ( xz) (Mpa)



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6. Material SAE 1045steel Case: 2 -Results



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Shear stress (yz)(Mpa)


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7. Material SAE 1045steel Case:3 -Results


Shear stress ( xy) (Mpa)


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Shear stress ( yz) (Mpa)



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8. Material SAE 1045steel Case: 4 -Results



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Shear stress ( xy) (Mpa)

Shear stress ( y z) (Mpa)


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Conclusion -Static analysis has been carried out in four cases for two materials. It isconcluded that SAE 1045 steel having better characters to IS-228.It is observed that theFactor of safety deteriorating with the increment in loads. According to FOS the loadsacceptable for the given geometry and material is up to 2.0E5 N on one wheel.The fourthload condition (2.5E5 N) suggestible as FOS is almost one.

The loads on rail road wheels are mainly cyclic loads, so it is mainly subjectedto fatigue. Due to these cyclic loads there will be formation of crack propagation in wheelwhich leads to fatigue failure.

Working temperature is considered as design temperature. There might be possibility for inducing thermal stresses with rise in temperature.

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