What restriction or condition for a spindle running in a linear guide (Abaqus)?

[SommerK]

Good evening everyone,

I am currently modeling in Abaqus a spindle that is suspended and can move downwards in a linear guide. The spindle pushes at the end with a force on a body. I just have a problem how to couple the linear guides and the spindle without restricting the movement. Everything I have tried results in errors. Only when I connected the spindle with the respective linear guides with tie constraints it worked, but this does not correspond to reality. At the beginning I thought that no constraint is enough because I defined a GeneralContact with Tangential Behavior. But Abaqus seems to think that the spindle is free floating in space and not connected to anything.

Do any of you have an idea for the coupling?

I would be glad about hints and tips.

Many greetings and have a nice evening.

 

[FEA way]

So the yellow spindle should slide out of the blue guides ? But the blue guides can be tied to the red bracket, right ? Then contact between the spindle and guides would make sense. Of course, you would also have to hold the bracket with a boundary condition.

 

[SommerK]

Hi FEA Way,

thanks for the quick feedback!

Exactly, the yellow spindle should be able to slide in the blue guides. I connected the blue guides to the red bracket via tie-constraint and held the bracket in place at the back. I tried it now in the assembly via position constraints, is that the right way?

 

[FEA way]

Constraints in assemblies don’t influence motion in analyses. To test connections you can run a modal analysis but keep in mind that contact will be frozen (nonlinear contact is not available in this procedure).

 

[SommerK]

I would like to do a static analysis where the bottom of the spindle presses on a surface. I just have no idea how to connect/constrain the spindle and linear guides... If I connect the spindle and linear guides with a tie constraint, the spindle will be held although in reality it could theoretically enter the body or?

 

[FEA way]

You said that you already followed my advice and connected the guides to the bracket with tie constraint and fixed the back of the bracket. For the spindle-guides interaction, you should use contact. That seems to make the most sense in this case. You may just encounter convergence issues with contact so try displacement control first.