XANSYS Message #: 20739

XANSYS Message: 20739 [Go back to message list]
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Subject: Re: Superelement/Substructuring
Author: Gerald Jones
Date: 2001-02-01 10:21:00

Stephane, I have been reading all of the postings on this topic and I think there needs to be some clarification as to how you wish to perform your crack growth calculations. Do you intend to use an ANSYS model with some feedback from your own crack growth code or do you wish to use the ANSYS model simply to supply a superelement matrix for your own crack growth code? In the first case, this could probably be accomplished by using meshing controls to ensure that the node pattern and node numbers on the interface between the crack region and the superelement region do not change. As was pointed out a couple of times the connecting nodes can not change. This would effectively limit your mesh refinement options in the crack region, however. This approach would require that the solid model be defined in ANSYS and the a set of areas or lines would exist on the boundary between the crack region and the superelement region. The only way to accomplish this with an IDEAS model would be through IGES and then the common areas/lines and the meshing would have to be done in ANSYS. Please note that it is possible to allow the connection nodes to change but then the superelement martix would have to be recalculated at each increment in crack growth. This would not save any computational time and in fact would probably increase the overall time. For the second case, the superelement matrix can be dumped out of ANSYS in an ASCII coded format but how you would utilize that data in your crack growth code is not obvious to any one not familiar with your software. Gerald Jones Stephane Pierre Bordas wrote: > Hello, > For research purposes, my group is thinking of using ANSYS as a tool to > generate superelement stiffness matrices for structural stress analysis. > At this point, we have an I-DEAS model from which we can export a > universal file. There may also be a way in which we could export our model > to an ANSYS compatible format, but this needs to be checked. > Our goal is to isolate a given region of this model, and make a > superelement out of the remainder of the model, whose behavior we are not > interested in. Then, we would use this superelement in conjunction with > another, more refined mesh for the region of interest and run some crack > propagation studies with the code that was written in our department at > Northwestern University. > We don't know much about Ansys, but it seems to us that it would be the > way to go. How feasible does it seem to you ? How would you go about doing > it ? Has any of you already done it ? Where can I find an example of this > kind of study/the format of the superelement file ? > In particular, is it possible to access the stiffness matrix representing > the superelement ? > Thank you very much for your help, > Stephane > Stephane P. Bordas > Ph.D Student in Theoretical and Applied Mechanics > Northwestern University, Evanston, IL, U.S.A > http://www.tam.nwu.edu/sbordas/ > "On ne doit appeler science que l'ensemble des recettes qui marchent, le > reste n'est que literature" > Paul Valery.

Posts possibly associated with message #20739		Author	Date
`20654`	`Superelement/Substructuring`	`Stephane Pierre Bordas spb276@`	`2001/01/30`
`20656`	`Re: Superelement/Substructuring`	`Martin Liddle`	`2001/01/30`
`20664`	`Re: Superelement/Substructuring`	`Kim Ravn-Jensen`	`2001/01/31`
`20691`	`Re: Superelement/Substructuring`	`Stephane Pierre Bordas spb276@`	`2001/01/31`
`20706`	`Re: Superelement/Substructuring`	`Dan Bohlen`	`2001/01/31`
`20739`	`Re: Superelement/Substructuring`	`Gerald Jones`	`2001/02/01`
`20960`	`Re: Superelement/Substructuring`	`K.S. Raghavan`	`2001/02/09`
`25447`	`Superelement/Substructuring Analysis`	`tap_club@`	`2001/06/29`