PML element in STKO

[Zouatine]

Dear STKO family,

I have been following the development of STKO in addressing Soil-Structure Interaction (SSI) phenomena, particularly through your webinars where you illustrated the use of the Domain Reduction Method. I am interested in doing the same but using Perfectly Matched Layer (PML) elements.

I understand that these element types exist in OpenSees for both 2D and 3D modeling, as indicated on the following webpage:

https://opensees.github.io/OpenSeesDocu ... s/PML.html

I am using the version 4.0.0 of STKO but was not able to find these elements in your list there ! Can u provide me with some guidance where i could find this element ? or if u have an exp for that , i would be great !

Thank u ,

[STKO Team]

It's not yet available in STKO.
However, it can be easily added using Python.

Just to speed up the testing: Do you have experience with this element? do you have some example to test it?
Are you starting with 2D or 3D?

[Zouatine]

Dear STKO team ,

thank you for your response !

Yes, I have some experience with this element. I’ve used it in 2D with OpenSees directly (without an interface), and I’ve also worked with it in 3D using LS-DYNA.

My intention is to use this element for both 2D and 3D modeling in STKO. I was hoping that the latest version already includes it. If it’s easy as u mentionned, I would really appreciate any guidance you can provide on how to implement it in STKO.

Thank you !

[Zouatine]

Dear STKO team ,

this is just kind of reminder.

Thank u,

[STKO Team]

After reviewing the documentation, implementing this feature appears to be fairly straightforward. However, there are certain parameters—particularly those related to distances—that might be automatically computed by STKO, which helps streamline the user experience.

Could you please clarify which parameters these are? If possible, a sketch or diagram illustrating how these distance-related parameters are defined or calculated would be very helpful.

pml_doubts.png (98.47 KiB) Viewed 3253 times

[Zouatine]

Thank you for your response STKO team,

The three elements , Thickness, RD_half_width_x, Depth are illustrated in the following figure :

PML_illustration.png (72.55 KiB) Viewed 3242 times

However, regarding the EleType, i think this would be determined automatically by the software, EleType_pos is Region-based element type (1–6), used for damping profile :

Code: Select all

EleType   Meaning	                            Damping Direction
1	       Regular domain	             None
2	       Left-side PML	                     X-direction only
3	       Left-bottom corner PML	     X + Y-direction
4	       Bottom-side PML	             Y-direction only
5	       Right-bottom corner  PML    X + Y-direction
6	       Right-side PML                      X-direction only

the source code of the elements is in the following link :

https://github.com/OpenSees/OpenSees/bl ... L/pml_2d.f

Thank you , waiting for ur kind response.

[STKO Team]

Few more questions:

• However, regarding the EleType, i think this would be determined automatically by the software, EleType_pos is Region-based element type (1–6), used for damping profile :

  It is feasible to auto-determine the EleType_pos, as far as we can assume that the interior domain has the boundary faces aligned with the global axes. Is this something we can assume?
• The reference point on the interior domain is always at the Center-Top geometric location of the interior domain?
  If so, STKO can autocompute it and thus auto-compute the related distances
• How many elements are along the thicknesses? Always 1? or it can be user-defined? I ask this because we can also automate the generation of the PML elements (similar to what we do with the ASDAbsorbingBoundary3DAuto)

[Zouatine]

Dear STKO team,

Thank you for your response!

The short answer to the first two questions is yes. Regarding the last question, in my previous simulations, I always used one element, and according to the research paper on the implementation, only one element is shown.

Waiting for your kind response,

[Zouatine]

Dear STKO,

I wanted to kindly remind you about the above mention method , and ask whether you had time to take a look at my answers.

Thank you,.

[STKO Team]

Dear user, yes we started working on it. We'll let you know when we have a first version you can test.

UPDATE:
Looking into the source code it seems the c++ code input is different from the user documentation. Also the integers for element types are given for the 2D case but not for the 3D case.