put RBE in subcases
Altair Employeehello to everyone, I´m new in the forum and I´m having my first experience with hypermesh/optistruct.
In my model (a omega beam) I created 2 different load steps (bending and torsion), the bending is applied in the middle with a RBE2 and when i run the analysis I notice that during the torsion a stifness is added due to the RBE. I tried to use the RBE3 but doesn´t work well, because the displacement of the nodes is not due to a rigid body, but how if there was a force applied to each node (different displacement for each node).
is it possible to put the RBE2 in the bending subcase, so I will not have that stiffness during the torsion?
thanks in advance for help.
Answers
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Hi,
Deactivating is possible if the rigids are created with MPCs but not with rigid elements.
Please check more about MPCs in OptiStruct help and let us know if you need any help
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Hi Prakash,
thank you very much for answer.
I created a MPC (equation) where the load have to be applicate, and then I applicate the force in the middle but i don´t have any displacement!
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I attach the models with MPC and also the first one with RBE2
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Hi prakash,
have you found any error? I can´t find it
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Hi prakash,
Hope you doing well. In this pictures you can see this the spring elaborating with the stiffness. So behavior i need to simulate in optistruct. Can you please tell me what parameters i have to define and if you have any model please share me.
Thanks
Dinesh
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I would suggest to use RADIOSS instead of OptiStruct for the same.
Please create a separate forum post instead of posting in threads which are not relevant
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Altair Forum User said:
Hi,
I am trying to run your model and it gives a laminate error. Is there a reason for having Steel layer of ply in the laminate?
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Altair Forum User said:
Hi,
I am trying to run your model and it gives a laminate error. Is there a reason for having Steel layer of ply in the laminate?
yes there is, it´s a omega steel profile with a laminate pasted on it. I also tried to create a tool for the bending, but during the torsion subcase there is always the stiffness on the top of the profile.
Are you running the analysis? the analysis doesn´t show me any error...
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hi prakash,
I´m tring to use MPC but the results are quite strange, the displacement have to be the same for each node because the load is applied by a trasversal bar, but in the results is different.
I attach the .fem file, I´m tring to make the nodes on the laminte (from 459 to 486) dependents by the node where is applied the force (17635), is it possible to do that? is it correct?
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I see the issue, what is the weight factor used for the dofs?
Is it same or different?
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It's the same... but i don't know if it has to be the same. So in my problem I have a bar where is applied 1kn of vertical force. How can I set it?
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now the model with MPC works at the same way of using the RBE3 (MPC displacement picture), but I need a uniform trasversal displacement, like in the way of using the RBE2 (RBE2 displacement picture)
can I set the MPC to obtain that result?
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Hi,
I am working on it and I see that the dispalcement contour is different for MPC and RBE2. I will get back to you soon.
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After go through some theory this is expected because there will be no relative displacement between nodes when using RBE2 but this is not the case with MPC or RBE3
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Hi prakash,
thank you very much, you confirmed my suspect. Infact I created another model with a rigid tool to achieve that result (other topic).
thank you very much again.
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Basically it works like an equations. Where the sum of displacement of independent nodes is equal to displacement of dependent node.
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