topic Re: Boundary Conditions in Simulation Mechanical Forums (Read-Only)

Boundary Conditions

Anonymous — Thu, 27 Sep 2012 16:57:36 GMT

I have recently started using Autodesk Simulation and am finding a lot easier to use than some alternative software. However, I would like to add low(or non)- reflecting boundary conditions to my model so that any p- or s- waves travelling through a solid element are not reflected and an infinite area is represented. I have the equation for stress in the normal direction, however it involves using the derivative of the displacement. Can anyone advise me as to how I can implement these BC?

Many thanks.

Re: Boundary Conditions

Sualp.Ozel — Wed, 10 Oct 2012 15:51:25 GMT

I don't fully understand the question. Can you please clarify your issue. What analysis type are you in? what type of boundary condition you are trying to implement, what will it represent in real life?

Best Regards

Sualp Ozel, PE

Product Manager

Digital Simulation
Autodesk, Inc.

Re: Boundary Conditions

Anonymous — Thu, 11 Oct 2012 12:58:46 GMT

I am wanting to run a transient analysis. I have attached a simple model. Basically I have at least two sources of energy attached to the ground, in this case towers with a force applied to them and I want to see how this affects displacement through the ground (this can be seen by making tower 3 & 4 invisible int he attached model) and the effect of other towers nearby which do not have sources applied. I obviously can't model an infinite area of ground, so I want to apply boundary conditions to the edge of the ground which do not apply the waves to rebound (they are absorbed by the BC), but do not restrict movement of the ground. This I believe can be done using a non-reflecting boundary condition (equation in attached file). However I am not sure how to implement this.

Re: Boundary Conditions

Sualp.Ozel — Thu, 11 Oct 2012 15:20:28 GMT

"I think" I understand what you are trying to do 🙂 The boundary condition you are looking for is "Surface Frictionless Constraint".

Best Regards

Sualp Ozel

Re: Boundary Conditions

Anonymous — Thu, 11 Oct 2012 15:33:53 GMT

Thanks Sulap, that's great. Is there anyway I can view my displacement results on a log scale?

Re: Boundary Conditions

Sualp.Ozel — Thu, 11 Oct 2012 17:17:34 GMT

As far as I know the Results interface does not let the user change the Legend to log scale. But here is what you can do; select several nodes in the Results interface, right click and create a Graph. When you are in the Graph vie, you can right click and edit the Y axis to a log scale. Hope this helps Best regards Sualp Ozel, PE Product Manager Digital Simulation Autodesk, Inc.