r/LSDYNA • u/LoxumovCofe • 3d ago
Difficulty modeling SPG
Hello everyone,
I am trying to model a semi-brittle material failure using SPG. I am new to LS-DYNA and I am having issues understanding this one problem. It is a very basic problem, and that is why it is so frustrating.
As you can see in the attached image, I have a basic rectangle of 2.5x2x1.4mm. The nodes are separated by 0.15 mm. The scale has to be this small for my purposes.
The boundary conditions are as follows: the bottom face is fixed, the highlighted nodes are displaced in the z-direction(yellow arrow) by 0.1mm in 0.5seconds, I have the mass-scaling on I have tried running without it and the issue remains.
https://reddit.com/link/1w214et/video/vzqoeyyhcemh1/player
After I ran the solver I get the issue that you can see in the attached video. Can someone please explain to me what is happening and how can I avoid it?
Here are my material and SPG cards.
*SECTION_SOLID_SPG
$ id elform aet unused1
1 47 0
$ dx dy dz ispline kernel unused2 smstep msc
1.5 1.5 1.5 0 2 30 0
$ idam fs stretch itb msfac isc boxid pdamp
2 170000000 1E+10 2 1 0 0 -0.001
*MAT_ELASTIC
$ ID ro E pr da db k unused1
1 1900 1.7E+10 0.31 0 0
3
u/epk21 3d ago edited 3d ago
I would suggest to start with standard fea and learn how to use workbench ls dyna and the format of keywords and k files. Dennis Chen has many videos.
Then you can look on his tutorial on spg metal cut.
Search for
Ansys LS-Dyna Tutorial - Metal Cutting Simulation using SPG from dcfea
For a tension example see here, use same approach. https://www.lstc-cmmg.org/_files/ugd/157719_2abe73ee4e8a4f61a2255c4576141b87.pdf
Also there is a guide for spg in this work group
https://www.lstc-cmmg.org/spg