Learning Forum

[Anthony Gagnon-Proulx]

For my project, I need to run a sim using ALE and then save the resultant deformed geometry (idealy in .step, but .stl or .obj works too). When using the DEFGEO keyword and then opening the D3Plot with LS-prepost, I can go to post->output and select ASCII.stl, select entire model to the latest timestep and write the .stl files, but when doing so I get 1 .stl file per part at the initial state, and 1 .stl file per ALE mesh group, but those .stl are 1Kb in size and contain nothing when opened.

[Ian Do]

Hello Anthony,

Please clarify ...

[a] describe the physics of your problem - send a free body diagram of the process (both steps)

[b] how would you want to run the model in the 2nd run after the mapping? Which parts are to be converted into LAG or any other formulation (if that is what you want)? 

Thanks! With more info we may be able to make a suggextion. Thanks!

Ian Do

[Anthony Gagnon-Proulx]

Hi Ian, 

I cannot upload diagrams of my problem as part of our departemental R&D policies, but here are some clarifications:

In the first process, lets say I have an explosion happening close to a metal plate, which will deform under the pressure. This process is modeled using the Multi-Material ALE method. The desired output would be a .stl or .step of the metal plate in the deformed end state. 

The .stl or .step will afterwards be used in a CAD software (SolidEdge) in order to guide the design of other parts and components.

To be clear, the goal is not to use the deformed model of a first process to run a second process within LS-Dyna.

Thanks, 

Anthony

[Ian Do]

Hi Anthony,

Correct me ...

So you have all ALE parts in this model:

MMG1 = HE 

MMG2 = air 

MMG3 =solid metal plate

Let it go ==> then you want to convert MMG3 (solid plate) shape at the end and write it into a tet LAG mesh.

Is this what you want?

Ian

 

[Anthony Gagnon-Proulx]

Hi Ian, 

You are correct for the model with 3 ALE part, and yes converting to LAG mesh should allow me to then export to .stl, 

Anthony

[Ian Do]

Hi Anthony,

This can be very complex and require a support submission!

You can try, based on the the hypothetical set up i gave above:

The keyword is *ALE_MESH_INTERFACE

The user just wants to mesh MMG3: nowrt=1000 is enough for his purpose.

The parameters volrat,edgmin,edgmax in the example below will probably need to be adapted to the user’s model.

*SET_MULTI-MATERIAL_GROUP_LIST

              33

                3

*ALE_MESH_INTERFACE

$   mmgset      nowrt    volrat

               33        1000         0.4

$   edgmin    edgmax

            0.05         0.15

Regards,

Ian Do, PhD