Imperf Keyword In Optistruct

Jerome Teoh
Jerome Teoh Altair Community Member
edited April 16 in Community Q&A

Hi,

I am using imperfection keyword cards to solve a structure analysis in optistruct (non-linear static=), it is a cylinder with compressive loading.

I am wondering what the scale factor does?

For example, what is the difference if I specify a factor of 0.25 instead of 1? Will it alter the shell thickness basd on that or slightly move the nodal locations?

Lastly, what is the typical factor that is being used?

 

Thanks,

Jerome Teoh

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Best Answer

  • harte
    harte
    Altair Employee
    edited April 16 Answer ✓

    Hi Jerome,

    The scale factor is a multiplier on the magnitude of the imperfection. So in your hypothetical of using 0.25 versus 1.0, the magnitude of the deformation will be 1/4 of the true value.

    It doesn't affect shell thickness, it only affects nodal location. The imperfection is only considered in the solver calculation, and the final H3D result file still contains the mesh of the original structure. Usually the magnitude of the imperfection is very tiny, otherwise, it is recommended to create a new model.

    I'm not entirely sure what is the typical factor used, but as stated above usually the magnitude of the imperfection is very tiny.

    Regards,

    Greg.

Answers

  • harte
    harte
    Altair Employee
    edited April 16 Answer ✓

    Hi Jerome,

    The scale factor is a multiplier on the magnitude of the imperfection. So in your hypothetical of using 0.25 versus 1.0, the magnitude of the deformation will be 1/4 of the true value.

    It doesn't affect shell thickness, it only affects nodal location. The imperfection is only considered in the solver calculation, and the final H3D result file still contains the mesh of the original structure. Usually the magnitude of the imperfection is very tiny, otherwise, it is recommended to create a new model.

    I'm not entirely sure what is the typical factor used, but as stated above usually the magnitude of the imperfection is very tiny.

    Regards,

    Greg.

  • Jerome Teoh
    Jerome Teoh Altair Community Member
    edited October 2023

    Greg,

    Thank you the information. One last question, is it possible to check value of the true value.

    I would be interested that if my factor is 1, how much shifthing of the nodal location.

    Best,

    Jerome.

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