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The substructure file wr_coupl_pe1.ins



The model of the track in substructure file wr_coupl_pe1.ins is built up according to the following figure:

analyse_wr_coupl_pe1.gif

The track consists of four masses trc(track), ral_r, ral_l and grd(ground). Mass grd have no degrees of freedom, the mass only follows the designed track curvature. Mass trc can have degrees of freedom, in lateral-, vertical- and roll- direction of motion. The normal case is to have constrains to mass trc in all directions except in the lateral direction. The constraints are set in substructure file wr_coupl_pe1.ins. If the user wishes to have other constraints he/she must make a local copy of the wr_coupl_pe1.ins-file, and edit the constraints which are in the beginning of the file.
The rail masses ral_r and ral_l has vertical and lateral degrees of freedom, but they do not have any inertia. The equation of motion for the rail masses are solved in differential equations of the first order.

If constraints are removed in vertical and roll direction the user must supply the model with vertical spring between trc and grd, otherwise the model will accelerate downward because of the earth gravitation.



The model consists of the following springs and dampers:

knwr, knfr
Stiffness between wheel and rail. Stiffness knwr refers to the contact point #1 i.e. the tread. Stiffness knfr refers to the contact point #2 i.e. the flange. The two springs are always perpendicular to the contact surface. The stiffness in the spring shall be given in a memory field as a function of the contact angle. Recommended values can be found in file knwr_p.runf.

Variable pknwr controls if the contact stiffnesses shall be modeled. pknwr can be given the following two values:
0 =   Creates a Hertzian contact stiffness
1 =   Creates a linear contact stiffness.
If Variable pknwr has been set equal to 0, please check that the pre-stress force knwr.F0 also is set equal to 0. If not, the Hertzian stiffness will not be correct.

However often the stiffness between wheel and rail are much stiffer compared to other stiffnesses in the model, primary suspension, rail fasterns, track-ground-stiffness,,,etc. Therefore will the results almost be the same for both the Hertzian and linear contact stiffness. The Hertzian contact stiffness is a much better model but it also gives longer simulation times.

kzrt, czrt
Vertical stiffness and damping between ral and trc. The spring and the damper coefficient should refer to the vertical flexibility in rail pad and rail fasteners. If mass trc have vertical constraints, kzrt and czrt must also include the vertical flexibility in the ballast. The stiffness and damping should be defined as a property defined in calc_coupl.html#p_*. Recommended values for wooden and concrete sleeper track can be found in the file knwr_p.runf.

kyrt, cyrt
Lateral stiffness and damping between ral and trc. The spring and the damper coefficient should refer to the bending of the rail and deformation in the rail fasteners. The stiffness and damping should be defined as a property defined in calc_coupl.html#p_*. Recommended values for wooden and concrete sleeper track can be found in the file knwr_p.runf.

kytg, cytg
Stiffness and damping between trc and grd. The spring and the damper coefficient should refer to the lateral stiffness of the ballast. The stiffness and damping should be defined as a property defined in calc_coupl.html#p_*. Recommended values for wooden and concrete sleeper track can be found in the file knwr_p.runf.



The creep forces are in substructure-file wr_coupl_ne1.ins calculated in a lookup table. For a more detailed description in how to calculate creepage and creep forces, the interested reader can find more information in theory_creepage.html.



Input:

The model of the track in substructure file wr_coupl_pe1.ins is built up in a very similar way as the substructure file wr_coupl_ne1.ins. The main difference between wr_coupl_ne1.ins and wr_coupl_pe1.ins is that the two individual rails have own degrees of freedom.

In addition to the required input data variable names in wr_coupl_ne1.ins above, substructure file wr_coupl_pe1.ins also requires the following variables:

Stiffness and damping between rail and track
kyrt_$2r = Lateral stiffness between right rail and track
kyrt_$1 = If kyrt_$2r not can be found
kyrt_ = If kyrt_$1 not can be found
kzrt_$2r = Vertical stiffness between right rail and track
kzrt_$1 = If kzrt_$2r not can be found
kzrt_ = If kzrt_$1 not can be found
kzrt.F0_$2r = Pre-stress force in spring kzrt_$2h (The pre-stress force shall be positive)
kzrt.F0_$1 = If kzrt.F0_$2r not can be found
kzrt.F0_ = If kzrt.F0_$1 not can be found
0. = If kzrt.F0_ not can be found
cyrt_$2r = Lateral damping between right rail and track
cyrt_$1 = If cyrt_$2r not can be found
cyrt_ = If cyrt_$1 not can be found
czrt_$2r = Vertical damping between right rail and track
czrt_$1 = If czrt_$2r not can be found
czrt_ = If czrt_$1 not can be found

Where $1 is the number of the vehicle and $2 is the number of the axle.

The same naming convention has also been used on the rails on the left hand side of the vehicle. The names of the variables on the left side can be created by changing "_$2r" to "_$2l".


In addition to the generated variable names in wr_coupl_ne1.ins above, substructure file wr_coupl_pe1.ins also generates the following variables:

ral_$2r.y = Lateral position of the massless rail-head, tread right wheel
ral_$2r.vy = Lateral velocity of the massless rail-head, tread right wheel
ral_$2r.z = Vertical position of the massless rail-head, tread right wheel
ral_$2r.vz = Vertical velocity of the massless rail-head, tread right wheel

The same naming convention has also been used on the rails on the left hand side of the vehicle. The names of the variables on the left side can be created by changing "_$2r" to "_$2l".

The input and output parameters are defined under command func wr_coupl_pe1