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BoBo-vehicle with wheel/rail-contact creep_lookuptable_1


Example tutor_3_bobo_lookuptable_1 is very similar to example intro_tutor_3_bobo_pe3, but the model of the track has been created differently. In this example the wheel rail couplings are created with coupl creep_lookuptable_1. In example intro_tutor_3_bobo_pe3 the wheel rail couplings were created with command func wr_coupl_pe3.

The coupling coupl creep_lookuptable_1 is more flexible but slower in execution compared to func wr_coupl_pe3.

Download the example

Examine the directory "tutor_3_bobo_lookuptable_1"

Examine the vehicle in program RUNF_INFO

Program RUNF_INFO is a program which lists how masses and couplings in the model are linked together. Program RUNF_INFO is controlled by an input data file which is described in the RUNF_INFO users manual.

The files calc.out, runf_infor/Master.runf_infor and diags/runf_info.ps can now be closed.

View the vehicle in program GPLOT

Program GPLOT is a graphic program showing a three dimensional view of the vehicle.
Start program GPLOT with the file runf/tang_ideal.tsimf by:

In the GPLOT-window the mouse buttons are defined as:

If you zoom in to a bogie you can see that all couplings have a hot-spot. If you press the hot-spot with mouse button #1 you will get information of that specific coupling. Below is a close up of the first bogie of the vehicle:


Close the GPLOT-window, before continuing with the next section.

Perform a modal analysis of the vehicle

Program MODAL calculates all possible modes of vibration in the model. Number of modes are as many as the number of equations in the model. A low damped mechanical system of one degree of freedom has two complex conjugated eigenvalues. A high damped mechanical system of one degree of freedom has two real eigenvalues, both eigenvalues are negative. A self oscillating mechanical system is a system where the real part of the eigenvalue is positive.
Before the modal analysis starts, program MODAL linearizes the nonlinear equations by an amplitude defined in command modal_param.
Make a modal analysis of the vehicle:

Show animation of the lower sway mode of the BoBo-vehicle: □

Close the GPLOT-window, before continuing with the next section.

Perform a modal analysis taking car-body structural flexibility into account

Results from a modal analysis in a FEM-program of a car-body at free-free conditions are stored in the subdirectory patranr. This example shows how to take car-body structural flexibility into account:

Show animation of the first bending mode of the car-body: □

If you open the Deform->draw_deform popup menu. You will see that you have got 6 more eigenvalues, compared to the previous case modalRigid. These new equations arise from the three flexible modes added by program NPICK.

Please close the GPLOT-window, before continuing with the next section.

Modal analysis if program QUASI struggles in finding a quasi-static position

There are many reasons that program QUASI sometimes can have difficulties to find the quasi-static position of the vehicle. If this happens, there is a possibility to use program TSIM instead. In order to use program TSIM do the following:

Make a simulation on tangent track at 340[km/h].

Find the non-linear critical speed of the vehicle.

Make a simulation through a curve, without track irregularities.

Make a simulation through a curve, with track irregularities and in-line post processing.