Hello,

I am student working in the field of rail vehicle technology. In this context, I am working with the example model CTN_065 provided with the Simpack Rail module. I have three questions about this model:

1. Is the contact point between wheel and rail always vertically below the wheel centre point during the simulation with the predefined model settings? If a wheel runs over a vertical irregularity, then the contact point in reality is not necessarily always exactly under the centre of the wheel. Is this then ignored in the existing example model?
2. If you model a vertical track excitation using an input function in the distance domain, then you can have the derivatives of the function generated automatically in Simpack or model them as an input function as well. What happens if you select the option that the derivatives should be specified via an input function and then do not enter an input function? Is the derivative then simply ignored during the simulation?
3. I want to simulate a wedge test using an input function is distance domain for simulating the wedge as a single vertical track irregularity. I use Matlab to create an continous approximation of a wedge using a polynomial, which I then import into Simpack. When I only use the input function without calculation of the derivatives (I choose to set the derivatives with an input functions but do not set a corresponding input function), the simulation runs without problems. When I let Simpack generate the derivatives automatically or use derivatives I calculated in Matlab, the bogie jumps more than one meter high and the simulation ends. Does anyone know how to solve this problem or is it okay to simulate the wedge without derivatives?

Thank you in advance for your help.

Max
Edu