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Subject: Re: One question about the superelement matrix, K and M
Author: Homayoon Rezvani Naraghi
Date: 1999-11-18 17:07:00

Hello William,

I'm not sure I understood your problem. If I understood well, the quad 42's are
not part of the structure, but you used them only to easily mesh the model?

If this is the case, of course they should be deleted before the substructure
stiffness and mass matrices are generated. Substructures are nothing else than
parts of a structure, the stiffness and mass matrices, etc. of which are pre
calculated (instead of being calculated in the whole assembly). They should not
contain any extra elements that are not a part of the global structure.

Best regards,

Homayoon

Lu Wangming wrote:

> From: "Lu Wangming"

> Hi, dear all,

> I have one question about the superelement (substructure) matrices, such as
> the stiffness and mass matrices, K and M. while creating the 3d solid model,
> i first create a rectagular and then use the element type quad 42 to mesh
> this rectagular with the
> selcted mesh option (density), and then
> I switch the element type to brick solid 45 and
> extrude the meshed area along z direction to get
> the meshed 3d solid block (I also specified the mesh density along z before
> the extrude operation), and so, i finished the preprosessing---
> creating the 3d solid model.

> the next step is to choose the substructur to do the analysis by taking all
> DOF as master dofs (m, all, all), and write the mass and stiffness matrix,
> load vector, ect. and i got the stiffness matrix and mass matrix. But i have
> some question about the resultant K, and M for the strucutre. after I delete
> the quad 42 elements before solution, i also run the substruture, the
> resultant K and M are different with those i got without deleting the quad
> 42. So, i do not know which way is correct , can you tell me if anybody
> know this .

> thanks so much.

> regards,

> william, Lu

Posts possibly associated with message #6396AuthorDateScore
6394One question about the superelement matrix, K and MWangming Lu1999/11/18 
6396Re: One question about the superelement matrix, K and MHomayoon Rezvani Naraghi1999/11/18 
6397Re: One question about the superelement matrix, K and MWangming Lu1999/11/19