Moment or Force app...
 
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Moment or Force applied on surface in LS-Dyna  

 

Bill94
(@bill94)
New Member
Joined: 2 months ago
Posts: 2
November 16, 2020 1:00 am  

Hi all,

 

I'm a new gradute student in mechanical engineering with some Ansys background.

 

I'm pretty used to use the load interface from Ansys where you can select a face and applied some sort of load like a moment applied on a surface.

 

I've read the part talking about it in manual I but i'm not sure to understand how to use it.

 

My question is, in a simple case like a bar subjected to an axial moment, is there a way to select a face (an end of the bar) and apply a moment on that face? Or I have to use a contact tied with a rigid shell and apply a prescribed motion on it to simulate torsion?

 

Ultimately, I'd like to do the same with a force.

 

Thanks for your help


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Negative Volume
(@negativevolume)
Senior Member Admin
Joined: 2 years ago
Posts: 367
December 10, 2020 8:46 pm  

Hi @bill94

You can apply a load using *Load keyword. There are a lot of options though, I would probably use *Load_segment or *Load_segment_set and create a segment set of the face that you want to apply the load to. This example may help:

https://www.dynaexamples.com/implicit/basic-examples/basics-iii

Be careful though with sets, as the force that you input is not distributed among the segments in the set. Each segment is prescribed that load. 


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Bill94
(@bill94)
New Member
Joined: 2 months ago
Posts: 2
December 12, 2020 2:54 pm  

@negativevolume Thanks for the input.

 

I think I have not been clear in my question, sorry english isn't my first language. I attached a picture of what I wanted to do in Ansys. The load are applied by surface effect in Ansys I suppose. Is there anyway to do something similar, like with rigid element (RBE) ?

1607784879-Capture.png

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Negative Volume
(@negativevolume)
Senior Member Admin
Joined: 2 years ago
Posts: 367
January 4, 2021 3:00 pm  

@bill94 Ah I see. Yes to do this you would need to make that bottom surface of the part *Mat_rigid and define a local coordinate system to represent what you are showing (I can help with this if you don't know how). You can then use two *Load_Rigid_Body cards on that rigid part for the force and the moment. For each, change the DOF to the direction of the force / moment relative to your new local coordinate system and define a load curve (LCID) for your force / moment. 


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