The wheel/rail-coupling is a very important coupling for a railroad vehicle, especially in lateral direction.
Between the wheel-flanges and rails we have a clearance between 6-10 [mm],
which is about the same as we have in secondary and primary suspension,
at least on tangent tracks.
Therefore the wheel- and rail- profiles has a great influence on the lateral behavior of the railway vehicle.
In vertical direction however the contact point is very stiff,
why the vertical comfort not is affected much,
but it is important when calculating the vertical wheel rail forces.
Before copying an example, please check your current directory
If you wish you can use file mplotf/pure_creep.mplotf for plotting the results of the examples below.
creep_tanel_springs_1
Reference manual
Figure
Example
The most accurate model.
No precalculated wheel/rail geometry functions are needed.
Creep_tanel_springs uses the wheel and rail profiles directly.
On top of the rail a mesh of brushes are located,
all brushes are normal to the rail surface and all
have flexibilities in compression- and tangential- directions.
The compression flexibility solves the vertical problem,
the wheel profile is pressed towards the rail profile until
the enough vertical force is generated.
The shape of the contact surface is determined by the shape and the positions of the wheel- and the rail- profiles.
The contact pressure distribution calculated in the vertical problem,
are later used for calculating the tangential creep forces.
creep_fasim_1
Reference manual
Example
Wheel-rail forces are calculated by J.J.Kalkers routine FASIM.
The normal problem is solved by a contact spring knwr between wheel and rail, normal to the contact surface.
In order to speed up calculations the creep_fasim_1 uses precalculated wheel/rail-geometry functions
calculated by preprocessor kpf,
creep_lookuptable_1
Reference manual
Example
Wheel-rail forces are calculated by interpolation in a four dimensional lookup table.
The four dimensions are: absolute creep, direction of creep, spin and shape of contact ellipse.
The normal problem is solved by a contact spring knwr between wheel and rail, normal to the contact surface.
The creep_lookuptable_1 uses precalculated wheel/rail-geometry functions calculated in kpf,
in order to speed up calculations.
wr_coupl_pe1
Reference manual
Example
Convenience function which creates all rails and coupling elements which connects a rigid or flexible wheelset to the track.
For a detailed description please click on the link "Reference manual" above.
The creep forces in the contact point are calculated in the same way as in creep_lookuptable_1 above.
Number of contact points generated by creep_lookuptable_1 is determined from the wheel/rail geometry functions being used.
If the contact point not is jumping, only one point contact per wheel is created.
The name of the contact coupling will begin with the letters cpt, which stands for Contact Point Tread.
If the contact point contains more than one contact zone,
or if the contact point is jumping,
two contact couplings will be created.
This second contact coupling will begin with the letters cpf.
If the contact point jumps several times, it will switch between between the two contact coupling cpt and cpf.
The characteristics of the normal spring knwr can be linear or Hertzian.
This model is the most frequently used wheel/rail-coupling.
The model is both accurate and computer efficient.
wr_coupl_pr1
Reference manual
Example
Convenience function which creates all rails and coupling elements which connects a rigid or flexible wheelset to the track,
similar to wr_coupl_pe1 above.
In wr_coupl_pr1 the creep forces are calculated in J.J.Kalkers routine FASIM.
wr_coupl_pra1
Reference manual
Example
Convenience function which creates all rails and coupling elements which connects a rigid or flexible wheelset to the track,
similar to wr_coupl_pr1 above.
In wr_coupl_pra1 routine FASIM has been extended with Archard's Wear Law,
in order to calculate the wear in volume per unit time.
wr_coupl_ne1
Reference manual
Example
Convenience function that connects a rigid or flexible wheelset to the track, similar to wr_coupl_pe1 above.
This coupling is simpler than wr_coupl_pe1, because no massless rails are included in the model.
This model is faster than wr_coupl_pe1, but do not handle multiple contact points very well.
wr_coupl_nr1
Reference manual
Example
Convenience function that connects a rigid or flexible wheelset to the track, similar to wr_coupl_ne1 above.
In wr_coupl_nr1 the creep forces are calculated in J.J.Kalkers routine FASIM.
wr_coupl_nra1
Reference manual
Example
Convenience function that connects a rigid or flexible wheelset to the track, similar to wr_coupl_nr1 above.
In wr_coupl_nra1 routine FASIM has been extended with Archard's Wear Law,
in order to calculate the wear in volume per unit time.
wr_coupl_npol1
Reference manual
Example
Convenience function that connects a rigid or flexible wheelset to the track, similar to wr_coupl_ne1 above.
In wr_coupl_npol1 the creep forces are calculated by using Oldrich Polach's formula.
wr_coupl_nl1
Reference manual
Example
Convenience function that connects a rigid or flexible wheelset to the track, similar to wr_coupl_ne1 above.
In wr_coupl_nl1 the creep forces are calculated in a linear creep-creep force relation ship.
This wheel/rail-coupling has mainly been written for theoretical studies.
