RE: FE mesh to .stl

From: DANIEL CHARLES DAVIS (DANIEL@proton.com.my)
Date: Thu Jun 11 1998 - 07:22:34 EEST


Glenn,

You are correct that FE and STL tessalation are very similar. Even the
same CAD practices need to be followed (watertight, etc.). Conversion
should be an easy task, but I have to agree with the CATIA guy -- you
have lost me with your reasoning.

I interpret what you are saying as that you are starting from an FE
mesh. Huh? Where did it come from? The FE mesh is derived from the
same CAD model as would the STL file. There should be no multiple
conversions (i.e., CAD-to-FE and CAD-to-STL). They are both derived
from the same original data. Wouldn't the engineering process snapshot
look something like:

CAD-to-FEA-to-modified CAD-to-RP-to-..............
                               |
                       FEA verify

with the modified CAD data being verified in an FEA package while
concurrently being built on an RP machine. What am I missing here? Are
you saying that you want the same tessalation to be used for FEA and RP?
Not a bad idea, but I can't see it happening because one discipline will
have to rewrite their software to accept the others code. Converting
from FE to STL would be converting one approximation into another. Talk
about potential loss of data integrity and accuracy.

Also, who says that you need a solid to make an STL file? True, solids
make STL files with less hassle, but some parts are just not
realistically designable in solids. You must use a surfacer package for
those.

Regards,
Dan Davis
Head, RP&M Division
PROTON Berhad
Hicom Industrial Estate
Batu Tiga, PO Box 7100
Shah Alam, 40918 Selangor MALAYSIA
+60 3 515-2380

> ----------
> From: Monica & Glenn
> Whiteside[SMTP:SiderWhite@worldnet.att.net]
> Reply To: Monica & Glenn Whiteside
> Sent: Thursday, June 11, 1998 8:54 AM
> To: Rapid Prototype Mailing List
> Subject: FE mesh to .stl
> Importance: High
>
> Dear rp-ml:
>  
> Is FE mesh definition that far removed from .stl definition?  Why
> couldn't you easily convert FE mesh to .stl format and vice versa?
>  
> I've asked our local CATIA rep this question but all I got was a blank
> stare and a question "Why would you want to do that? 
>  
> Answer: To speed up design to RP model time!!  Any intermediate steps
> and conversions you have to do reduces data integrity and accuracy. 
> Going from FE mesh to surfaces then to an IGES conversion then to a
> solid and then finally to a .stl file?  What a pain in the extreme
> lower back!!  There has got to be a better way!!
>  
> Regards,
>  
> Glenn Whiteside
> Cessna Aircraft Co.
> e-mail: siderwhite@worldnet.att.net
> <mailto:siderwhite@worldnet.att.net>
>  
>  
>  
>  
>

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