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max ratio mathematical check

N/A

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

Re: max ratio mathematical check

N/A

Marco,
Can you attach the full .f06 file? Some previous messages may help indicate the
source of the problem.
Regards,
Jim

"Marco" wrote:
>
>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