Singularity Error in Frequency Response Analysis

Hi,

I am running a Frequency Response Analysis.

When I change the EIGRL entry to EIGRA, I get following error.

*** ERROR # 3432 ***
Singularity found in construction of constraint equations.
Usually this happens when a dof is defined as slave in more than
one constraints. For inertia relief analysis this problem may be
overcome with SUPORT definitions and/or PARAM,COUPMASS,1.

This error occurs in module 'asmbdrv'.

How this can be resolved ?

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Rahul Rajan_21763

There has to be some issue with the mpc/rbe constraints.This error usually happens when for some reason a slave dof cannot be assigned to a constraint equation, because all the dofs in the equations are already spced are defined as slaves in other equations. Please also review the autospc table.
If it is possible to share the model then please share, we will take a look.

chetanwable

@Rahul R

1. there are no SPC/MPCs,

2. also I just changed card from EIGRL to EIGRA, run with EIGRL is ok, but run with EIGRA isn't ( there is absolutely no other change )

3. Also, same model with EIGRA - Normal modes is also ok.

Rahul Rajan_21763

can you please share the .out file of the run?

chetanwable

@Rahul R I shared it.

Rahul Rajan_21763

Thanks for sharing the out files. I am not pretty sure on the reason of error unless we take a look in to the fem file.Why you don't have any SPC/MPCs for analysis. Please also check the comments section of EIGRA card.

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