Boundary Conditions

Altair Forum User

Hi,

 

I'm a university student doing a topology optimisation using HyperMesh and OptiStruct.

 

I've imported my part from an ACIS file and meshed it using 2D automesh and volume tetramesh.

 

I'm now trying to fix both ends of the wing (it's the central wing of the twin fuselage aircraft WhiteKnightTwo, see screenshot) with 0 degrees of freedom but when I choose surfaces on the constraints option it only shows a single constraint in the middle of the surface whereas I want to constrain the entire area of the surface.

 

Can anyone help?

 

Thanks,

 

Luke

<?xml version="1.0" encoding="UTF-8"?>

<?xml version="1.0" encoding="UTF-8"?>

Altair Forum User

When you apply BC on a surface, normally, all nodes attached to this surface will be on defined contraints.

Another method: you can define BC directly over 'nodes' which is found in the list (see my screenshot).

 

Are you sure about such fine density of your mesh ?

On the 2nd screenshot, are you sure about Poisson's ratio > 0.5 ?

<?xml version="1.0" encoding="UTF-8"?>

tinh

Hi,

You can map load from surf to nodes

 

Please refer to this:

http://forum.altairhyperworks.com/index.php?/topic/13415-faq-31how-to-map-loads-onto-different-mesh-configurations/?hl=%2Bload+%2Bgeom#entry18518

Rahul Rajan_21763

Hi,

The above behaviour of showing one symbol of constraint for selected face is intended behaviour.In Hypermesh Optistruct user profile this happens when you apply loads on geometry.

Once you submit job it will map that contstraint to all nodes associated to constrained surface.

Regards

Rahul R

Altair Forum User

Thanks for the replies. I selected the nodes by window in order to select all the ones on the end surfaces which worked. With regard to:

 

Altair Forum User said:

When you apply BC on a surface, normally, all nodes attached to this surface will be on defined contraints.

Another method: you can define BC directly over 'nodes' which is found in the list (see my screenshot).

 

Are you sure about such fine density of your mesh ?

On the 2nd screenshot, are you sure about Poisson's ratio > 0.5 ?

 

The poisson's ratio is for carbon fibre reinforced plastic. I agree it's rather large but that's the number that I found on a CFRP manufacturers website. Do you think it seems reasonable? Also the reason for the fine mesh is that I'm conducting a topology optimisation of the entire internal wing structure so I assumed that in order to get any kind of detailed internal structure I would need a fine mesh.

 

Thanks again,

 

Luke

Altair Forum User

Hi Luke,

 

Please cross check the poison's ratio. I am not really sure if the poison's ration you have is in major material direction of angled direction.