Slip in the rigid railroad track - ABAQUS model

[Kamyar_K]

Hello everyone,
I am currently working on a 3D FE model in ABAQUS, focusing on simulating thermal force resulting in a rail break which generates a gap in the rail.
Model description:
This model applies a compressive load in the longitudinal direction, aligned with the rail length, equivalent to the thermal force, causing rail displacement as a result of this loading. Friction-based components are used in series with elastic elements to define the rail-sleeper and sleeper-ballast interactions. Non-linear spring elements simulate the elastic properties of fasteners and ballast in the vertical, lateral, and longitudinal directions. Friction-based elements model the interaction between normal force and friction coefficient for each nodal degree of freedom, allowing for potential slip at the rail-sleeper and sleeper-ballast interfaces. The friction-based element is defined longitudinally at the rail-sleeper interface, and both laterally and longitudinally at the sleeper-ballast interface. Slip in the model occurs at the interface with the lowest longitudinal track resistance value (which can be calculated by dividing the slip force by tie spacing).
Issue:
My issue is that even when I apply very high values for the normal force in the friction elements at both interfaces, which significantly increase the longitudinal track resistance, I still see some displacement happening when there really shouldn't be any.
I am wondering what might be the reason that generates the displacement in a very rigid track in longitudinal direction. I also want to know the correct sequence of elements at each interface—should the spring come first, or the friction elements? Could anyone give me some guidance/comment on these questions I have?
Thank you in advance and have a great rest of your day

 

[FEA way]

So you are using connector elements with frictional and elastic behavior ? What types of connectors ? Is the figure taken from an already published paper that you can share for reference ? It would be good to see some description and explanation of the symbols used there. Unless you can show your setup with connector and spring elements displayed with symbols and names.

 

[Kamyar_K]

Yes, connector elements were used to define friction and elasticity. This model has been also adopted in other paper which it can be seen in link below, some other characteristics are mentioned there.

https://journals.sagepub.com/doi/fu...pVhoMRQmg8a1YfG8xl93TYqYqpC1Xq6b5UPrbqAFC6Yzw

The connectors and their properties are listed below:
1- Elastic element in rail-crosstie interface (simulating the fasteners elasticity)
2-1- Friction element in rail-crosstie interface (simulating the slip behavior between rail and crossties)
2-2- Elastic element coupled with friction element (at the same connector with 2-1)
3-1- Friction element in crosstie-ballast interface in longitudinal direction
3-2- Friction element in crosstie-ballast interface in lateral direction (at the same connector with 3-1)
3-3- Elastic element coupled with friction element in crosstie-ballast interface in vertical direction (at the same connector with 3-1)
3-4- Elastic element coupled with friction element in crosstie-ballast interface (at the same connector with 3-1)
4- Elastic element in crosstie-ballast interface

You can also find the screenshots related to each one.

1

2-1

2-2

3-1

3-2

3-3

3-4

4

 

[Kamyar_K]

Anyone?