Challenge

Week 2 Railwheel and Track

AArjun Ghotekar7 Oct 2022

Case 1: Multiply the bearing load by 5 times and compare the results with the load of 100000 N (As done in week 2 video). Compare the Total Deformation, Equivalent stress, and the life under both the loads

Introduction to Rail Wheel:

A train wheel or rail wheel is a type of wheel specially designed for use on railway tracks. A rolling component is typically pushed onto an axle and mounted directly on a railway carriage or locomotive, or

Indirectly on a bogie, also called a truck. Wheels are cast or forged and are heat-treated to have a specific hardness. New wheels are trued, using a lathe, to a specific profile before being pressed onto an axle. All wheel profiles must be regularly checked to ensure proper interaction between the wheel and the rail. Incorrectly trued, or worn out wheels can increase rolling resistance, reduce energy efficiency and may even cause a derailment. A railroad wheel typically consists of two main parts: the wheel itself, and the tire (or tyre in British English) around the outside. A rail tire is usually made from steel, and is typically heated and pushed onto the wheel, where it remains firmly as it shrinks and cools. Monobloc wheels do not have encircling tires, while resilient rail wheels have a resilient material, such as rubber, between the wheel and tire.

Rail wheel design can be observed as given below:

Rail Profile:

The rail profile is the cross sectional shape of a railway rail, perpendicular to its length. Early rails were made of wood, cast iron or wrought iron. All modern rails are hot rolled steel with a cross section (profile) approximate to an I-beam, but asymmetric about a horizontal axis (however see grooved rail below). The head is profiled to resist wear and to give a good ride, and the foot profiled to suit the fixing system. Unlike some other uses of iron and steel, railway rails are subject to very high stresses and are made of very high quality steel. It took many decades to improve the quality of the materials, including the change from iron to steel. Minor flaws in the steel that may pose no problems in other applications can lead to broken rails and dangerous derailments when used on railway tracks. By and large, the heavier the rails and the rest of the track work the heavier and faster the trains these tracks can carry.

There are so many types of rail profiles. Some of them are listed below:

Flat bottom Rail
Bull Head Rail
Grooved Tram Rail

Analysis

We are interested in structural analysis of Rail Wheel and Track setup.

We can see in above image that wheel is attached with shaft and in contact with running rail.

Due to shaft, there is bearing load acts in the wheel bore.

We are concerning about stress, strain and deformation variation at different bearing loads.

So cases on the bases of bearing loads are as given below:

CASE_1: Bearing Load = 100000 N

CASE_2: Bearing Load = 500000 N

Geometry:

Material secification

Mesh

General mesh size is 50mm and face sizing is 40mm

___________________

Procedure:

Import model “Skill_Lync_Railwheel_Track.x_t” in geometry.

By default material is “Structural Steel”.

Connections:

Make contacts based on definitions.

Contact_1:

Contact Body = Wheel

Target Body = Running Rail

Type: Frictional

Friction Coefficient: 0.3

Contact_2:

Contact Body = Shaft

Target Body = Wheel

Type: Frictionless

Joints: Joint_1

Connection Type: Body-Ground

Type: Fixed

Body: Running Rail

Joint_2

Connection Type: Body-Ground

Type: Translational

Body: Shaft

Joint_3

Connection Type: Body-Ground

Type: Planar

Body: Wheel

Boundary Conditions:

After meshing as described above, create Boundary Conditions as given below:

Analysis Settings:

No. of Steps = 5

Solver Type: Direct

Output Controls: All “Yes”

Non Linear Controls: Force Convergence: ON

Time Step Controls:

Here we want Wheel to translate on Running Rail up to distance 500 mm with 100 mm on each step.
Also there is a load imposed by a carriage transferred to shaft and from shaft to Wheel through Hole.

Solution:

After giving proper boundary conditions, create desired solutions for output results.
Create Solutions for “Equivalent (Von Mises) Stress”, “Equivalent (Von Mises) Strain” for over all setup and for Wheel and “Total Deformation”.Also create solution for “Fatigue Life”.

Results:

Now we will see all results with comparison.

Results for CASE_1 and CASE_2 are as given below:

Equivalent stress

Case 1 case 2

stress plot

csae 1 case 2

stress values

case 1 case 2

stress value for wheel

case 1 case 2

Total deformation

case 1 case 2

Deformation plots

case 1 case 2

Deformation Data:

case 1

Equivalentt starin

case 1 case 2

strain plots

case 1 case 2

Strain values

case 1 case 2

fatigue life

fatigue life curve

case 1 case 2

Fatigue values

case 1 case 2

Contact

case 1 case 2

Case 2: Implement a User-defined result and calculate the Total Deformation from this result and check if it is the same as that obtained by the inbuilt result by ANSYS for a load of 100000 N.

User Defined Result:

In many situations, we have seen customers ask for ways to output custom results from Ansys Mechanical. The usual results like Total Deformation, Equivalent Stress or Equivalent Plastic Strain may not be enough for our needs. Depending on the requirements, we can create User Defined Results to output the needed result.

There are various output quantities given in the Worksheet of Ansys Mechanical.

Somehow, any results not output automatically, than we can write expression for that result and get needed results.

If we want Total Deformation results, then we can use algebraic equation for Resultant Deformation in the form of vector quantities.

Here we want to find out the Total Deformation as a User Defined Result and want to check if it is similar to inbuilt result.

So, symbol for the Deformation used is U.

So, for expression we can write it in the form as given below:

UDF results for both cases are as given below:

user define inbuilt result

From the observations of comparative results, we can see high amount of increase in Stress and Strain.
User Defined results are same as inbuilt results and near same in both cases.
From the contact status we can observe little change in track and little sticking due to higher pressure in case of 500000 N loading. So it can be dangerous and leads to Derailment and power transmission loss.
366.97 Mpa. So there will be plastic deformation or permanent deformation can happen.
As per results, we can see that fatigue life in 100000 loads is minimum 5.62^ E5 cycles and for 500000 loads it is only3529.5cycles.
So we should avoid higher loads for safety purpose.

Animation

Case 1

Total def