modal analysis

Altair Forum User
Altair Forum User
Altair Employee
edited October 2020 in Community Q&A

how to perform modal analysis of cylinder subjected to external pressure

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Answers

  • Altair Forum User
    Altair Forum User
    Altair Employee
    edited May 2018

    Hi,

     

    Please refer to OptiStruct user guide for tutorials on modal analysis. 

  • Simon Križnik
    Simon Križnik Altair Community Member
    edited August 2018

    Hi,

     

    I want to perform a modal analysis of an inflatable tube. The analysis is split in two steps- inflation step and subsequent modal step.

    The pretension is carried over into modal through STATSUB (PRELOAD) from inflation step. Inertia relief is applied through PARAM>inrel -2

     

    However the results are not matching the experiments sufficiently. Can the internal overpressure be directly included in modal analysis instead of indirectly through preloading?

     

  • Altair Forum User
    Altair Forum User
    Altair Employee
    edited August 2018

    Hi Ivan,

     

    I think this is the reason:

    From Help:

    Preloading applied to a Normal Modes Subcase is not transferred to modal solution sequences (with the same modal space and boundary conditions) in the same input deck.

  • Simon Križnik
    Simon Križnik Altair Community Member
    edited August 2018

    Thanks Prakash, I will try a different modeling approach for a better correlation.

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