ERROR # 153 Exactly zero pivoting encountered during Numerical Factorization
Altair EmployeeHello,
I am a member of Ka RaceIng, the formula student team from Karlsruhe. I make a size optimization of a tubular rear frame. The objective is 'minimize weighted compliance' and the constraint consists of a maximum mass. Unfortunately, I often get this error message:
Messages for the job:
*** ERROR # 153 ***
Exactly zero pivoting encountered during Numerical Factorization;
the model may have rigid body mode.
Solver error no. = -514
spc set id = 2
index = 1
Possible reasons are:
1) insufficiently constrained model,
2) having rigid body mechanisms within the model,
3) extremely ill-conditioned rigid element sets,
4) extremely thin shells (as used for skinning) that have MID2/MID3,
5) gap elements with extremely high stiffness (KA, especially KT or MU).
Check the model and rerun the problem.
(MECHCHECK may be used to find the rigid body modes. To do so,
change the input to be an eigenvalue analysis and add MECHCHECK.)
(WARNING: results obtained with MECHCHECK cannot be used because
the model is changed internally.)
This error was detected in subroutine bcsmtxfct.
All 1D elements are connected and the frame is constraint at 6 points, so I don't think that there are not enough boundary conditions. At the moment, I have no idea how to solve this problem. Please find attached the simulation model. Could you please help me?
Thank you very much .
Kind regards,
Kilian Kiesel
Answers
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Hi,
I think the problem is coming from the DIM2 design variables. Upon deleting the inner radius variable, optimization works.
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