Hi,

I have used successfully and for several times the infinite elements to avoid wave reflection in SHPB test modeling.You have to create in your 3D model a partition on the boundary of the substance where you intend to use infinite elements. The infinite region should be meshed using swept meshing algorithms. The sweep direction should be set to be coincident with the infinite direction. After meshing the infinite region using acoustic elements AC3D8R, you can write the inp file. Then, change  AC3D8R  by  CIN3D8 in the inp file. Finally, you can import the modified inp file in Abaqus CAE and submit your job.

Hi,

I have applied infinite elements several times, but I never faced the kind of problem you are explaining here. Though I will write the way I apply infinite elements.

I make a thin partition at the infinite boundary and then sweep mesh it with single row of elements using acoustic elements (just to distinguish these elements in *.inp file). Then in the *.inp file change acoustic elements to infinite elements.

Hope it helps you.

regards,

--

Anshul

Dear Amshul Faye,

I have managed to make the infinite parts using *NGEN, *NFILL, *ELGEN

and importet them in abaqus/cae

I have never tried this with infinite elements but one possibility might be to mesh the two regions independently and use a mesh tie constraint.

Dear Kianoosh Koocheki,

  could you please explain for more detail how did you make the infinite part using *NGEN, NFILL, ELGEN because I got the same error message that you explain.... I appreciate any explanation

Thanks in advance  

Hiba,

hi 

i think the shape of your infinite element at corner is not true 

they must be like this exactly .... 363 , 364 is true . but pic 38 is not 

Hi,

I have used successfully and for several times the infinite elements to avoid wave reflection in SHPB test modeling.You have to create in your 3D model a partition on the boundary of the substance where you intend to use infinite elements. The infinite region should be meshed using swept meshing algorithms. The sweep direction should be set to be coincident with the infinite direction. After meshing the infinite region using acoustic elements AC3D8R, you can write the inp file. Then, change  AC3D8R  by  CIN3D8 in the inp file. Finally, you can import the modified inp file in Abaqus CAE and submit your job.

at least on side of infinite element must be in contact to one side of finite element

Hi Saadatfar,

Yes, creating a partition maintains the noad numbering order between finite and inifinte elements.

Dear coleagues

I could not find a way to force abaqus do the element numbering for me, and I made a .inp for infinite elements then imported it in abaqus cae and then merged the finite and infinite parts together.

Thank you all for your help

Came to this link as I encountered a similar situation using 'CIN3D8' infinite element. We have to manually modify the INPUT file generated and replace the 'AC3D8' acoustic element. There are a couple of YouTube tutorials on this.

Regarding the error message, there is an option to orient the acoustic elements such that the open face should always face outwards. You can use 'Assign Stack Direction' icon on the mesh module or 'Mesh-->Orientation-->Stack' option from drop-down menu for this purpose.

While running the model, make sure you you are using the modified INPUT file to run the job. (Check chapter 19-Job module in Abaqus/CAE user's manual for more details in running job)

Hope this helps someone who comes here next time. :)

Came to this link as I encountered a similar situation using 'CIN3D8' infinite element. We have to manually modify the INPUT file generated and replace the 'AC3D8' acoustic element. There are a couple of YouTube tutorials on this.

Regarding the error message, there is an option to orient the acoustic elements such that the open face should always face outwards. You can use 'Assign Stack Direction' icon on the mesh module or 'Mesh-->Orientation-->Stack' option from the drop-down menu for this purpose.

While executing the model, make sure you are using the modified INPUT file to run the job. (Check chapter 19-Job module in Abaqus/CAE user's manual for more details in running job)

Hope this helps someone who comes here next time. :)

Edit:

Adding a reference to Abaqus manual belonging to Cambridge University.  

Refer 28.3 section for more information on infinite elements ABAQUS:  

https://things.maths.cam.ac.uk/computing/software/abaqus_docs/docs/v6.12/pdf_books/ANALYSIS_4.pdf 

How can I assign the Stack Direction in a 2D axisymmetrical model? I can't use swept algorithm for meshing! Please help me

I got a follow up question, even you successfully get the infinite element after you modified the element type manually, how you can select the part and attribute section property to it? I am really really struggling about this, when I select this part, the available list of section won't show the predefined infinite section, please help me.

Sincerely and best regards,

Mengli

You may see this links : 

https://www.youtube.com/watch?v=CaTd5ppSPA4

https://www.youtube.com/watch?v=T-rla6r1RHg

I saw both of them, they are really indeed helpful, but they did not go as far as material and section assignment, where my question lies, can you tell me how I can select the pre-set acustic infinite section to the selected part?

Thanks so much!

Also, I read the ABAQUS User Manuel, it was said that Acoustic infinite sections must be assigned to regions of parts that have a reference point associated with them.

But I defined the referece point, still cannot choice the acoustic finite element when I select the part that mean to be infinite element.

They mentioned some reference point and node ray, I never find where to specify these....

Please help everyone, much appreciate it ! 

Best regards,

Mengli

see this video:

https://www.youtube.com/watch?v=T-rla6r1RHg

Dear @ Song Mengli have you solve this issue.

CAN YOU SEND ME THE CAE FILE ?

This is the file I created it for the error. "Infinite elements must share a complete face with one and only one other non-infinite element. The elements in element set ErrElemInfiniteAdjacency are not properly connected."

Can you help me know this error?

I have another problem

i have vertical load in my model and i have to absorb propagating waves in boundaries, but when i place infinite boundary in bottom, the model have large displacements, so what should i do ?

Dear An Thai

I got some experience for building a 3D model with infinite boundaries. I got the same problem as yours and solved the error. Have you solved your issue now?