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FSI: inconsistent number of eigenvalue

User: "Nazrin"
Altair Community Member
Updated by Nazrin

Hello everyone,

I want to do flexible riser simulation. riser pinned at two end (constrain at xyz translation, free xyx rotation) + upward force (top tension) define as load. The loadsteps in optistruct are:

 

1. Linear static:

    spc: defined
    load: defined

 

2. modal Analysis:
    spc: defined

    method (struct): defined

    statsub (preload): linear static

 

I get an error during importing op2 file into acuconsole-eigenmode manager.

 

<?xml version="1.0" encoding="UTF-8"?>576407684_eigenvalueerror.thumb.PNG.29ebea7fa45534896e318fbeba43002b.PNG

 

The error only occur when there are two subcase (linear static + modal analysis).  If i only do modal analysis without linear static, i can import the op2 file without any error.

 

attached is the optistruct and acusolve file.

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    User: "acupro"
    Altair Employee
    Updated by acupro

    It may be that the OP2 file for Eigenmode Manager can only contain output from the modal analysis subcase - so maybe make sure there is no output requested for the linear static subcase.

    User: "Nazrin"
    Altair Community Member
    OP
    Updated by Nazrin

    Dear /profile/5282-acupro/?do=hovercard' data-mentionid='5282' href='<___base_url___>/profile/5282-acupro/' rel=''>@acupro,
     

    so maybe make sure there is no output requested for the linear static subcase.

     

    How can I exclude linear analysis in 'output: op2 card'?

    User: "acupro"
    Altair Employee
    Updated by acupro

    Sorry - I'm not an OptiStruct user.  You may need to ask that question in the OptiStruct forum.  Describe the two load cases, and indicate you don't want to write output from the first load case (Linear Static) to the OP2 file.  You only want output from the Frequency/Modal load case written to the OP2 file.  Probably include the .hm file again, too.