Export Coupled Acoustic Structural Matrices Abaqus2020

AB 2020-12-15

Dear all,

I would like to export the mass and stiffness matrix of a model containing acoustic structural coupling as .mtx files in Abaqus 2020.
These matrices are expected to be unsymmetric due to the coupling term although there exists a symmetric form, too. The acoustic-structural coupling is realized via Tie-Constraints.
I experience the following problem. The exported coupled matrices, although definitely looking different than matrices without coupling, do not look like any form mentioned in the theory documentation of Abaqus. Is there any documentation on the matrices which are exported with acoustic-structural coupling? Is it even possible to export mass and stiffness matrices in this case correctly?

The lines to create the matrices in the input file are the following:

**-----------------------------------------------------------------

** step for generation of system matrices .mtx file

**-----------------------------------------------------------------

*Step, UNSYMM=YES

*Matrix Generate, MASS, STIFFNESS

*Matrix Output, Stiffness, Mass, FORMAT=MATRIX INPUT

*End Step

I also tried a symmetric step and different output formats. But I couldn't recognize any form of the matrices I know.

Thanks in advance and best regards,
Alexander Brauchler