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Convergence issues with *LOAD_NODE_POINT (LSDyna)

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Posts: 13
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(@mmia1)
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Joined: 1 year ago

Hi

I tried to apply hydrodynamic water load at pipe as nodal load like below:

*LOAD_NODE_POINT
$# nid dof     lcid    sf
        1   1     1       1.00
        2   1     1       2.00
        3   1     1       3.00

.............................

  9570   1      1      1.00

I have a load curve (lcid) as below:

*DEFINE_CURVE_TITLE
$# lcid sidr
        1 0
$#   a1           o1
       0.000      0.000000
      1.000000 1.000000

 

The sf (scale factor) is basically my load that are applied as pipe nodes (please see image). I am doing implicit analysis and found that if I exclude these load steps (*LOAD_NODE_POINT) and include only hydrostatic load, my model ran completely. However, if I include *LOAD_NODE_POINT steps, then my model is not converging and aborted after just 0.1 sec (total time = 1 sec). Could anyone suggest me what to do. I am stuck at it for a while.

 Screenshot 2023 10 25 110421
1 Reply




Negative Volume
Posts: 665
Admin
(@negativevolume)
CEO
Joined: 6 years ago

Hi @mmia1

It seems like your model is getting over constrained. Also, you are trying to expand those nodes outward radially with a force correct? I'm not sure you would get that result even if the model ran because the force would be applied in the global x direction. 

I think you want to use *Load_segment_set. You can read more about how it's implemented and the directionality in the manual. 

https://ftp.lstc.com/anonymous/outgoing/web/ls-dyna_manuals/DRAFT/DRAFT_Vol_I.pdf

Page 3275. 

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