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Subject: Re: contact stiffness, convergence, and solution ti me.
Author: Dan Bohlen
Date: 2002-09-30 14:55:00

One way avoid the .tri file hit on your hard drive is to redirect it to the bit
bucket
i.e.. on UNIX > /dev/null.

It's been a long time, but you may also be able to suppress the writing of the
.tri file using /FDEL command..

> -----Original Message-----
> From: Bill Bulat [mailto:billbulat@y...]
> Sent: Monday, September 30, 2002 12:57 PM
> To: xansys@yahoogroups.com
> Subject: Re: [xansys] RE: contact stiffness, convergence, and solution
> time.

> Hi Roberto,

> The sparse solver may be used in a generation pass at release
> 6.1 (it's a
> beta feature).

> I tried it and it seemed to work with a very small test
> model. I don't see a
> .tri file in my working directory however. Presently, I'm not
> certain you
> could do an expansion pass (I believe you need the .tri file
> for that). You
> CAN do a use pass, however. If you have 6.1 and don't need to do an
> expansion pass, you might consider substructuring.

> Bill Bulat
> ANSYS Inc

> ----- Original Message -----
> From: "Roberto Porto"
> To:
> Sent: Monday, September 30, 2002 11:28 AM
> Subject: Re: [xansys] RE: contact stiffness, convergence, and
> solution time.

> > I tryed to use substructuring tecnique, but I gave up
> because it is still
> > using the frontal solver and has a limit on the number of
> elements used
> > (46000), which made it much slower than solving the full
> model with sparse
> > solver.
> > The substructure method doesn't allow you to choose the solver.

> > Regards,

> > Roberto Porto
> > DSC Engenharia

> > ----- Original Message -----
> > From: "Newland, Bill"
> > To:
> > Sent: Monday, September 30, 2002 11:48 AM
> > Subject: RE: [xansys] RE: contact stiffness, convergence,
> and solution
> time.

> > > It's been a long time since I have done substructuring. Another
> limitation
> > > of the frontal solver which was also the only solver
> available for the
> USE
> > > pass was a limitation on the master degrees of freedom. I
> recall hitting
> > > this limitation quickly with Contact52's in the USE pass
> interfacing
> solid
> > > model portions defined as superelements.

> > > I was under the impression that Substructuring had become somewhat
> > obsolete
> > > with the advent of Solid92's and new solvers, but now
> that the Sparse
> > solver
> > > can be utilized for the Substructuring technique - maybe
> this technique
> > > should be re-evaluated as a possible method to reduce run
> time for solid
> > > model assemblies interfaced with Contact170/174's.

> > > I was wondering if anyone has had any recent
> Substructuring experience
> in
> > > this regard.

> > > Bill Newland
> > > Bell Helicopter, Textron

> > > -----Original Message-----
> > > From: Metrisin Joe [mailto:jmetrisin@f...]
> > > Sent: Friday, September 27, 2002 7:06 AM
> > > To: 'xansys@yahoogroups.com'
> > > Subject: [xansys] RE: contact stiffness, convergence, and
> solution time.

> > > Several years ago, I wrote a macro that would
> automatically substructure
> a
> > > contact problem so that once the superelements were
> generated, you only
> > had
> > > to iterate on the contact elements. It wasn't very
> efficient because
> you
> > > had to use the frontal solver for the generation pass,
> which was about
> 20x
> > > slower than solving the entire model once with the PCG solver.

> > > The latest version of ANSYS now lets you do superelement
> generation with
> > the
> > > sparse solver, so it might be worth trying this technique again.

> > > Joe Metrisin
> > > Florida Turbine Technologies, Inc.

> > > Date: Thu, 26 Sep 2002 13:20:17 -0500
> > > From: "Newland, Bill"
> > > Subject: contact stiffness, convergence, and solution time.

> > > My compliments to Don Shaffer on expounding the need of
> faster solution
> > > time for detailed models with contact elements!

> > > Thanks to CAD transfers, automatic tetrahedron element
> meshing, and
> > contact
> > > elements - we are finally able to model interconnecting machine
> components
> > > as they really are. Now, if we could just do it without
> tying up our
> > > computers for days.

> > > One model I solved recently has about 800,000 dof's , 41
> Contact 170/174
> > > interface sets, and about 20,000 Contact 170/174
> elements. I did get
> good
> > > results - but it took 6 cpu DAYS on an SGI Octane.
> Substantial modeling
> > work

> > > was expended to get the model size down without deleting important
> detail.
> > > While it is amazing that ANSYS can solve a problem like
> this at all, a
> > much
> > > faster turn around time is required in order to be practical.

> > > Bill Newland
> > > Bell Helicopter, Textron
Posts possibly associated with message #42309AuthorDateScore
42300Re: contact stiffness, convergence, and solution ti me.Bill Newland2002/09/30 
42309Re: contact stiffness, convergence, and solution ti me.Dan Bohlen2002/09/30 
42326Re: contact stiffness, convergence, and solution ti me.Sheldon Imaoka2002/10/01 
42343Re: contact stiffness, convergence, and solution ti me.Bill Newland2002/10/01 
42351Re: contact stiffness, convergence, and solution ti me.Sheldon Imaoka2002/10/01 
42364Re: contact stiffness, convergence, and solution ti me.Bill Bulat2002/10/01