Learning Forum

[ORHUN OKCU]

Hello, I have been trying to do acoustic modal analysis of the room with absorption surface at the bottom of the room.  I could not add acoustic absorption surface into my modal. I created box and the imprint surface at the bottom by extrusion. (I followed the book named Acoustic Analyses Using MATLAB and ANSYS). When I select this surface, the question mark is appear. How can I solve this problem. By the way, I am using student lisence. Thank you in advance. 

[ErKo]

 

 

 

 

Hi

 

That should work only on a single non shared face belonging to an acoustic region made of a 3D part/body.

Also one needs to activate a damped solver since this adds damping – done under analysis settings.

One can see this error when trying to solve your system as it is – it will prompt the user to use the damped solver.

Thank you

 

 

 

 

[ORHUN OKCU]

First of all, thank you for response. I turned the damping on but I have still question mark. How should I add the surface to my body? I have created surface from the sketch by extrusion. Then I select the operation as a imprint faces.

[ErKo]

 

 

 

 

I meant face  – so it can be scoped to a face belonging to a part/body. So for sure there is something going on with the geometry – can you show it please and the list of all parts involved (also it can not be an interior face).

So do a simple example - do a cube - and scope the absorption surface to one side/face - that should work.

Erik

 

 

 

 

[ORHUN OKCU]

 

I scoped by the using both geometry selection and the named selection. I selected from the outside as well. But question mark still remains.

 

[ErKo]

 

Try to start from a new project – create a BOX in designmodeler. Then apply it to one of the sides/faces of the cube and that should work (as shown below) – try that.

[ORHUN OKCU]

Sorry, I have done what you said. I think I am doing something wrong. What I have done is create the box. Then I assigned the air as material to acoustic region. Then I scope one face of the cube for absorption surface. I have still question mark. This is my screen.

 

[ORHUN OKCU]

How can I lift the question mark from the acoustic region without material assignment? Sorry for bothering. I am real beginner.

[ErKo]

No worries – can you show the details of your solid body (want to see what material it has), and show me the analysis settings just like I showed.

Also take away that material assignment and use directly as shown below:

 

[ORHUN OKCU]

[ORHUN OKCU]

Thank you so much. Have a nice day

[ErKo]

 

 

Not in Designmodeler – in modal acoustics/mechanical like I showed in my last image – make sure you select air like shown in my last image - if you have that (Air) and it does not work press the button indicated below to show the error message – all the best

Erik

 

 

[ORHUN OKCU]

It worked. Thank you very much.

[ErKo]

That is great - can you share and say what you changed to get it to work please incase someone else has the same issue.

Please share below

[ORHUN OKCU]

I have assigned the air for the solid body from the body detail page. The question mark next to absorption surface turned to check. For those who encounter a problem about adding absorption surface make sure that your solid body material is air.

[ErKo]

Thank you - yes, we need to have acoustic properties/material for acoustic regions - so we need at least speed of sound and density for the material properties for acoustic regions.