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Subject: Re: Poll results for xansys - optimization
Author: Paris Altidis
Date: 2001-02-23 13:49:00

The ideal scheme would be :
a) Knowledge base Engineering (Not necessarily in electronic form) - to weed
out unsuccessful scenarios. Experience may still be under your nose.
Problem is, we don't look there.
b) Use your optimizer for the remainder.

Paris Altidis
Staff Engineer
Borg Warner Automotive
708-547-2719
paltidis@a...

> -----Original Message-----
> From: Christopher Wright [SMTP:chrisw@s...]
> Sent: Friday, February 23, 2001 11:30 AM
> To: XANSYS
> Subject: Re: [xansys] Poll results for xansys - optimization

> >I think that I can overcopme the "fiddle factor" with optimization
> >if I see that the payoff is there.
> I may as well chip in here. There's really not much general value in
> optimization because it's restricted to a very narrow area. Problems like
> 'optimal' fillet radii are trivial and not worth learning the necessary
> vocabulary, let alone waiting around for results. Real engineering optima
> involve matters such as cost, schedule and producibility. Weight savings
> is sueful, but only if it comes with a cost or time savings. I once
> worked on a rib-stiffened cylindrical shell where the 'optimized'
> structure really saved a lot of weight by adding a great many small,
> closely spaced stiffeners. But the fabrication costs were monstrous--it
> wasn't an optimum anything.

> Engineering designs often require specific types of components--you're
> stuck with the off-optimum just because plate and fasteners and rolled
> shapes in any old size you want.

> The biggest problem (apart form inability to import parameterized CAD
> geometry) is that by the time you have enough information to 'optimize' a
> design, it's already pretty much cast in concrete, particularly if you're
> waiting on a CAD model. A good example is a pressure vessel with a flat
> head--you can figure out the 'optimum' combination of head and shell
> thickness for the least material, but FEA won't explain that a flat head
> is a rotten idea from the outset.

> OTOH, I daresay situations involving proof of concept lend themselves to
> both parameterization and optimization but the use of small models for
> studying physics seems to have gone out of fashion.

> Christopher Wright P.E. |"They couldn't hit an elephant from
> chrisw@s... | this distance" (last words of Gen.
> ___________________________| John Sedgwick, Spotsylvania 1864)
> http://www.skypoint.com/~chrisw

Posts possibly associated with message #21325AuthorDateScore
21301Poll results for xansys - optimizationDan Bohlen2001/02/23 
21303Re: Poll results for xansys - optimizationDanny Levine2001/02/23 
21311Re: Poll results for xansys - optimizationParis Altidis2001/02/23 
21321Re: Poll results for xansys - optimizationChristopher Wright1991/02/23 
21323Re: Poll results for xansys - optimizationMark Tate2001/02/23 
21325Re: Poll results for xansys - optimizationParis Altidis2001/02/23 
21334Re: Poll results for xansys - optimizationChristopher Wright1991/02/23 
21342Re: Poll results for xansys - optimizationFrank Exius2001/02/24 
21360Re: Poll results for xansys - optimizationShen-Yeh Chen2001/02/26 
21371Re: Poll results for xansys - optimizationParis Altidis2001/02/26 
25378Re: Poll results for xansys - optimizationChris Rogers2001/06/28