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#76337 - 03/21/22 03:33 AM FEA tools for caesar 2019: negative jacobian flag to check?
vermaccio Offline
Member

Registered: 09/05/17
Posts: 152
Loc: italy
i tried to check a dummy leg using FEAtools in caesar2019.

i inserted loads, temperature, pressure, sizes...

i run and the calculus is overstressed.

So i inserted a reinforcing pad.

i run again and... the calculus stops because there are some probems with mesh. (i thing due to reinforcing pad)

the progams suggest to check mesh (i checked: it is ok) OR to flag the option "accept negative jacobian".

i don't find where is this flag to check.

anyone knows?

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#76338 - 03/21/22 07:33 AM Re: FEA tools for caesar 2019: negative jacobian flag to check? [Re: vermaccio]
mariog Offline
Member

Registered: 09/29/07
Posts: 792
Loc: Romania
If the Jacobian is negative for a given node, the element is invalid. In fact the software asks you to check mesh or to accept a result potentially wrong. How much wrong?- I suspect you'll never know accepting negative Jacobian. BTW, I don't know where is this option.

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#76339 - 03/21/22 09:26 AM Re: FEA tools for caesar 2019: negative jacobian flag to check? [Re: mariog]
Borzki Offline
Member

Registered: 09/16/04
Posts: 710
Loc: Traz
You can try to refine the mesh. Try to find this option in the settings, otherwise ask other members in this forum who have experience the same error.

One way to check your FEA result is to perform a mesh convergence study although you might experience singularity at junction, where the result never converge. But I believe the software have considered already a distance as a function of R/T from the junction, in which results can converge. Just confirm.

Warm Regards,
_________________________
Borzki

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