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12-12-2007 11:05 AM

Hello,

I have to perform mathenatical checks on a FE model, and the customer asks for a

max ratio check, that is the max ratio of matrix diagonal to factor diagonal must

not exceed 10E+7. With our previous MSC Nastran 2005 version I obtained a suitable

value with a SOL103 run. Now with NX Nastran 5.0 SOL103 I cannot get a good result:

I always get

*** USER INFORMATION MESSAGE 4158 (DFMSA)

---- STATISTICS FOR SPARSE DECOMPOSITION OF DATA BLOCK KXX FOLLOW

NUMBER OF NEGATIVE TERMS ON FACTOR DIAGONAL = 6

MAXIMUM RATIO OF MATRIX DIAGONAL TO FACTOR DIAGONAL = 1.0E+15 AT ROW NUMBER

4

followed by a long list of rotational DoFs everyone with max ratio = 1e+15 and matrix

diagonal = 1e-10 (all rotational DoFs of solid elements).

How can I get a result analogous to MSC.Nastran one? Am I looking at the wrong number?

Thanks

1 REPLY

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12-13-2007 08:58 AM

Marco,

Can you attach the full .f06 file? Some previous messages may help indicate the

source of the problem.

Regards,

Jim

"Marco"

>

>Hello,

>

>I have to perform mathenatical checks on a FE model, and the customer asks

>for a

>max ratio check, that is the max ratio of matrix diagonal to factor diagonal

>must

>not exceed 10E+7. With our previous MSC Nastran 2005 version I obtained a

>suitable

>value with a SOL103 run. Now with NX Nastran 5.0 SOL103 I cannot get a good

>result:

>I always get

>

> *** USER INFORMATION MESSAGE 4158 (DFMSA)

> ---- STATISTICS FOR SPARSE DECOMPOSITION OF DATA BLOCK KXX FOLLOW

> NUMBER OF NEGATIVE TERMS ON FACTOR DIAGONAL = 6

> MAXIMUM RATIO OF MATRIX DIAGONAL TO FACTOR DIAGONAL = 1.0E+15 AT

>ROW NUMBER

> 4

>

>followed by a long list of rotational DoFs everyone with max ratio = 1e+15

>and matrix

>diagonal = 1e-10 (all rotational DoFs of solid elements).

>

>How can I get a result analogous to MSC.Nastran one? Am I looking at the wrong

>number?

>

>Thanks

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