Catia Structural Analysis and wandering shells, Please Help!

[TravisAG]

I'm trying to perform an anlysis using shell elements in V5R11. The model is comprised entirely of surfaces, all of which live in a single open body. Most of the surfaces were created with the "fill" function, that is I constructed a wire frame in space, and filled the space between the lines. This was mostly to force me to keep the surfaces simple, which I though would help...

The problem I am running into now is that catia seems to either need a single surface or an assembly (so that the joints can be defined as welds), where as I currently have an open body containing several surfaces. I have tried using the join as well as the heal functions, however I get errors along the lines of "non connex surface" and "non manifold result" (which is frustrating becuase the geometery is really very simple and clean, I don't understand what causes these errors). If I turn of the Check Connexity function on the join tool, I can get a single surface, but when I go to mesh, not all the edges automaticaly join, and when I try to manually simplify although the mesh looks like it is joined where I want it. critical surfaces will appear to seperate in the analysis.

My question is as follows: Is there a better way to join surfaces, or to trick catia into treating an open body as a single surface? I have noticed that in the online documentation there are several complex surfaces that show up as a single surface in the model tree. How were they created? Someone somewhere along the line made them, and used some process to strip away all of their history..how?

Ultimately I'm looking for a way to do iterations quickly with this part, and dealing with a massive assembly of surfaces just doesn't seem like a very efficient approach.

Thanks in advance for the help, and if it would be at all useful I could try to upload some screen shots for people to look at.

-Travis

 

[Ashvanth]

Hi travis,
I am very new to analysis. But i can help in suggesting you in creating a single surface using join or heal commands.
The reason for you getting this error non connex surface" and "non manifold result" is bcoz--- of the merging distance that is keyed in the the join or the heal window.
by default it wud be .001mm.(this is advisable and recomended). But unless and otherwise stated by ur customer to maintain that value u can increase the value and get ur surfaces still closer and join or heal them.

But u must be careful in keying in the values for merging distance in heal command. bcoz the more u play with those the more the surfaces get bumped at corners which may get unnoticed it it's a big part. Also if u havee tgnt surfaces don't give larger angles in heal command while creatting single surfaces that is a very critical field in the command which totally changes ur geometry sometimes. i have experienced it. please check the "check connexity" tab and go for the join command.

But i wud rather prefer to goto heal though it's critical bcoz it's got freeze option in it which is actually very helpful. we can freeze one face and pull the other within the merging distance.
Hope my suggestions help u to some extent.

Regards,
Ashvanth Viswanathan.
INDIA.