Dynamic/Implicit. How to define a rolling condition with an initial speed and good contact? Please!
Dynamic/Implicit. How to define a rolling condition with an initial speed and good contact? Please!
(OP)
Hi everybody,
I really need your help, i really have been struggling with this issue for weeks now.
I want to define a rolling condition of a wheelset travelling at 70Km/h on a rail track.
I have defined three steps:
1)Static step: contact initiation with an imposed vertical displacement of the wheelset;
2)Static forces initiation: removal of the displacement and contemporary application of the static loads at the bearings.
3)Dynamic/implicit step:
T=1s;
Increment size:0.0005s
NLGEOM ON
Velocity BC (rotation and longitudinal speed) on a RP coupled (distributed coupling) with the wheelset axis. Instantaneous load.
I have tried tons of strategies, but i never got a realistic rolling with good contact: either the axis deforms, the velocity field oscillates, the contact saturates completely.
I have attached some pictures of the model. The V field is after 0.002s of integration, and as can be seen it's not following the BCs.



I always have CSHEARF=(frictioncoefficient)*CNORMF.
You can also find attached the .inp file of the model.
Please i'm really looking forward for your help!
Regards,
Omar
I really need your help, i really have been struggling with this issue for weeks now.
I want to define a rolling condition of a wheelset travelling at 70Km/h on a rail track.
I have defined three steps:
1)Static step: contact initiation with an imposed vertical displacement of the wheelset;
2)Static forces initiation: removal of the displacement and contemporary application of the static loads at the bearings.
3)Dynamic/implicit step:
T=1s;
Increment size:0.0005s
NLGEOM ON
Velocity BC (rotation and longitudinal speed) on a RP coupled (distributed coupling) with the wheelset axis. Instantaneous load.
I have tried tons of strategies, but i never got a realistic rolling with good contact: either the axis deforms, the velocity field oscillates, the contact saturates completely.
I have attached some pictures of the model. The V field is after 0.002s of integration, and as can be seen it's not following the BCs.



I always have CSHEARF=(frictioncoefficient)*CNORMF.
You can also find attached the .inp file of the model.
Please i'm really looking forward for your help!
Regards,
Omar





RE: Dynamic/Implicit. How to define a rolling condition with an initial speed and good contact? Please!
RE: Dynamic/Implicit. How to define a rolling condition with an initial speed and good contact? Please!
It's actually a Dynamic/Implicit step.
You mean from the static part and the dynamic one? What would be the benefit of making an import of that part? The BC are already applied for the implicit job. Thank you for the cue.
Omar
RE: Dynamic/Implicit. How to define a rolling condition with an initial speed and good contact? Please!
When you do Std-to-Std import, you can try predefined field to start the analysis with the desired velocity. But I don't know, if the initial velocity can be applied to imported structures. Try it.