Unusual results with tie constraint

General Questions
1

Hello

I am doing a static analysis where I apply gravity load on my assembly. The problem I have encountered is with tie constraints.

As you can see from the picture that the marked parts are tied with eachother with sufficient search distance to form tie constraint

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Still, when I look at the displacement contors, the tied regions look like to have relative displacement between each other.

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It does not make sense to me. Shouldn’t the tied regions show same displacment contors ?
Here is the file

can anyone please help me identify the error

Thank you in advance

2

You can easily check if tie constraints work properly by running a frequency analysis. If anything is disconnected, it will be visible in low frequency modes.

3

Thank you for the suggestion.

My first mode starts at 50.65 Hz. I will not see any rigid body motion as my side plates are properly connected to the bottom frame. I still have the doubt that something is wrong as I see the maximum deformation in the plate where I suspect that tied constrain is not working there properly

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4

What if you animate the mode shapes ? The displacement values in frequency analyses are unphysical but deformed mode shapes can be very helpful.

You could also check the warning messages about nodes involved in tie constraints.

5

Your constraint is not working. If you use Automatic scaling of the results, you will be able to see it.

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In CalculiX, one surface must not be a master surface (red) in a tied constraint more than once. You have constraints part-81_to_part-49 and part-81_to_part-41, which violate this principle. You should merge such constraints into one (select both, right click, merge).

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6

I couldn’t check the file yesterday but right, that’s also why there’s a bunch of warning messages such as:

 *WARNING in gentiedmpc:
          DOF            1  of node       168558  is not active;
          no tied constraint is generated
 *WARNING in gentiedmpc:
          DOF            2  of node       168558  is not active;
          no tied constraint is generated
 *WARNING in gentiedmpc:
          DOF            3  of node       168558  is not active;
          no tied constraint is generated
7

Thank you so much. I really didn’t know this. I will try to correct it

8

I tried your suggestion @Matej, also thank you @FEAnalyst. My problem has been solved

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