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# Rigid Movements

## Rigid Movements

(OP)
Hi all,
Imagine have two plates are in contact and they're connected through bolts. The top plate is much stiffer than the bottom one.

Now,
At the bottom of the bottom plate there is a force applied vertically. Due to the presence of the top plate, the bottom will probably rigidly tilt but never bend.

Question: how can I simulate the stiffening effect of the top plate without actually use a top plate (saving elements and time)? I thought about use RBE but I'm not sure it's possible.

Hope the question is clear.
Thank you

### RE: Rigid Movements

If the difference in stiffness is large then you could model the top plate as rigid. This way you still have its geometry but the computational effort is much lower.

### RE: Rigid Movements

(OP)
I could. Should I glue the two plates? No sure if that would be too conservative. I don't see other ways though

### RE: Rigid Movements

I would define contact between these two plates in such a case. The analysis shouldn't take long with the top plate modeled as rigid.

### RE: Rigid Movements

where are the loadpaths ? Is the load coming into the lower plate and out to the "rest of the world" ? or into the lower plate transferred to the upper plate and then to the "rest of the world" ? If you're saying the upper plate is "just" hanging onto the lower plate (like a parasite) without any connection to the "Rest of the world" then how much load will it attract ? What's the loadpath out of the upper plate ? contact with the lower ??

### RE: Rigid Movements

Please add a picture of the entire structure; the described case makes no sense.
And why worry about saving elements? (that was a problem in the 70s-90s, not today)
And don’t use rigid elements; they don’t represent reality.

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