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# Creep-force – creepage relationship

- Introduction
- Download the example
- Cases in the runf-directory
- Create the creep-force – creepage relationships

## Introduction

The main calculation program CALC can model the connection between wheel and rail in many different ways. This tutorial shows you how to create curves of the creep-force – creepage relationship for the different couplings.

All models in this tutorial comprises three axles: axl_111, axl_112, axl_113 and axl_114, which all are running along the track at a constant speed of 10[m/s].

Pitch rotation of axle axl_111 is controlled by equation "func operp axl_111.vk= -Vo/ro_ - 0.25 * time". I.e. the longitudinal creepage in the contact point will start at zero and increase linearly. Creating a curve of the longitudinal creep-force – creepage relationship.

Angle of attack of axle axl_112 is controlled by equation "func operp axl_112.p= 0.1 * time". I.e. the lateral creepage in the contact point will start at zero and increase linearly. Creating a curve of the lateral creep-force – creepage relationship.

Yaw speed of axle axl_113 is controlled by equation "func operp axl_113.vp= -16 * time" and "func operp axl_113.vx= -12 * time". I.e. the spin creepage on right wheel will start at zero and increase linearly. Creating a curve of the lateral creep-force – spin creepage relationship.

Wheelset axl_114 also tests pure creepage. In this case the spin is created because of conical wheels.

## Download the example

- Download the tar-file pure_creep.tgz
  - List the contents of the tar-file: `tar -tzvkpf pure_creep.tgz`
  - Extract the contents of the tar-file: `tar -xzvkpf pure_creep.tgz`
- or the zip-file pure_creep.zip
  - List the contents of the tar-file: `unzip -l pure_creep.zip`
  - Extract the contents of the tar-file: `unzip pure_creep.zip`
- or go directly to the files: pure_creep

## Cases in the runf-directory

The tutorial comprises the following files:

File Name | Wheel/rail-coupling | Remark
pure_creep_pe0.tsimf | func wr_coupl_pe0 |
pure_creep_pe0-.tsimf | func wr_coupl_pe0 | Negative speed
pure_creep_pe0_mumod.tsimf | func wr_coupl_pe0 | Considerations are taken to change of friction coefficient due to the slip speed
pure_creep_pe3.tsimf | func wr_coupl_pe3 |
pure_creep_pe3-.tsimf | func wr_coupl_pe3 | Negative speed
pure_creep_pe3_mumod.tsimf | func wr_coupl_pe3 | Considerations are taken to change of friction coefficient due to the slip speed
pure_creep_pe4.tsimf | func wr_coupl_pe4 |
pure_creep_pe4-.tsimf | func wr_coupl_pe4 | Negative speed
pure_creep_pr3.tsimf | func wr_coupl_pr3 |
pure_creep_pr3-.tsimf | func wr_coupl_pr3 | Negative speed
pure_creep_pr3_mumod.tsimf | func wr_coupl_pr3 | Considerations are taken to change of friction coefficient due to the slip speed
pure_creep_pra3.tsimf | func wr_coupl_pra3 |
pure_creep_pra3-.tsimf | func wr_coupl_pra3 | Negative speed
pure_creep_fasim_1.tsimf | coupl creep_fasim_1 |
pure_creep_fasim_1-.tsimf | coupl creep_fasim_1 | Negative speed
pure_creep_fasim_1_mumod.tsimf | coupl wr_coupl_fasim_1 | Considerations are taken to change of friction coefficient due to the slip speed
pure_creep_lookuptable_1.tsimf | coupl creep_lookuptable_1 |
pure_creep_lookuptable_1-.tsimf | coupl creep_lookuptable_1 | Negative speed
pure_creep_tanel_springs_1.tsimf | coupl creep_tanel_springs_1 |

Run the files manually one by one, or execute script run_all.sh to execute all cases automatically.

## Create the creep-force – creepage relationships

All above cases will be plotted in the same diagram with file mplotf/pure_creep.mplotf.

Start the plotting activity by marking file mplotf/pure_creep.mplotf and select run with your right mouse button.

In the command options popup menu leave the ident fields empty, because all idents are already defined in the file.

If the popup-window MPdat-file "mplot_id.mp" exists appears, please answer Replace. Otherwise you will get many warnings about variables that already exists.