Learning Forum

[madhumitac93]

Greetings

I have been trying to simulate a radar antenna dish rotating 360 degrees around its axis and tilting 60 degrees to the right and left. I started the simulation in ANSYS 17.1 Static structural. I took three joints and applied joint loads with a 6 degree increment in a second (which is the velocity at which it operates) and defined 360 deg rotation for 60 seconds. For some reason the antenna dish and the ribs on either side of the dish start expanding while rotating. I cannot figure out why. Please help me find the reason for this or let me know if there's anything that is wrong with the inputs given. 

Regards, 

Madhumita

[dinhan0394]

just provide some picture about connection setting: where is the joint?

[peteroznewman]

Under Analysis Settings, you must turn on Large Deflection.

The default setting is off, which is a Linear model, so under large rotation, the points in the model travel along the tangent line (small deflection assumption) not around the circle (large deflection, nonlinear).

If this post answers the question, please mark this post with Is Solution to close the discussion, or ask a follow-up question.

[madhumitac93]

This is applied both sides and in another analysis I applied 360 deg rotation in a similar way underneath the electrical box.

 

[madhumitac93]

I turned large deflection on and ran the analysis but I was receving an error saying something like "element 2420 highly distrorted...". I have checked all the boundary conditions, joints and contacts but I haven't found any issue with them. Could you please suggest how I can avoid getting this error if I leave large deflectioin on.  

Thanks in advance

[peteroznewman]

There are many ways to address this error. Please review the information in:

Discussion #1

Discussion #2

Discussion #3

[madhumitac93]

Thank you for your response.

I have tried increasing the mesh at the contact region but it still shows the same error. I have applied a 60 deg rotation in joint load in 10 steps ( 6 degrees in each step). Is it possible that I am getting this error because of using body-ground revolute joint? I ran a quick analysis on a bearing model and I got rotation with the same settings i.e, large deflection on and 60 degrees in 10 load steps. The faces which I applied the joint to, are split in the middle as shown in the picture. Could this possibly be the problem too?  

[peteroznewman]

Create a named selection to look at element 2420 to see where it is. How do you know it is in the joint?

Also, 10 substeps may not be enough.  Try 100 substeps.

[madhumitac93]

I looked for the element which had high distortion and found it at the joint face as shown below:

So I increased the mesh density at that region. I will increase the no. of substeps to 100 and see if that works. 

Thanks again