recover MBD result for Fatigue analysis

Beta
Beta New Altair Community Member
edited October 2020 in Community Q&A

Hi,

 

I know the result from felxible body in MBD could be recovered for Fatigue analysis. However, I don't know how to do that. How can I use EL2PROP card to assign material? 

 

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Answers

  • Altair Forum User
    Altair Forum User
    Altair Employee
    edited December 2017

    Hi @Toan Nguyen

     

    Use ASSIGN H3DMBD to identify the flexbody file and create a bulk unsupported card for EL2PROP and key in the shown format:EL2prop.PNG

     

    Where the second field is the element set, followed by property type and property ID

     

  • Beta
    Beta New Altair Community Member
    edited December 2017

    Hi,

     

    Thank you for your answer. I have one more question. What should I input for FATDEF.Because I want to perform Fatigue analysis by recovering stress from MBD, I don't know how to assign data to this load collector. 

  • Beta
    Beta New Altair Community Member
    edited December 2017

    And if I usee12prop with element set id in the second field. Does that set have to contain element.? As far as I know, it must contain element in flexible-body, Is that true ??

  • Altair Forum User
    Altair Forum User
    Altair Employee
    edited December 2017
    Altair Forum User said:

    And if I usee12prop with element set id in the second field. Does that set have to contain element.? As far as I know, it must contain element in flexible-body, Is that true ??

    Yes,

     

    Altair Forum User said:

    Thank you for your answer. I have one more question. What should I input for FATDEF.Because I want to perform Fatigue analysis by recovering stress from MBD, I don't know how to assign data to this load collector. 

    I will check and get back to you soon. 

  • Altair Forum User
    Altair Forum User
    Altair Employee
    edited December 2017

    Hi @Toan Nguyen

     

    When creating the flexible body in OptiStruct, you have the option, to create a recovery file “MBDREC”. You have to the the corresponding option in the PARAM card.

    After the MotionSolve run, you have the option to load MotionSolve’s MRF and the *_MBDREC.H3D into OptiStruct in order to do transient stress recovery analysis.

     

    Please refer to MBDREC from OptiStruct help for more information on same. 

  • Beta
    Beta New Altair Community Member
    edited December 2017

    hi, thank you so much for quick answer.

     

    If possible, could you please give me an example of FEM file for Fatigue Analysis using MBD result recovery. I will be very thankful

  • Altair Forum User
    Altair Forum User
    Altair Employee
    edited December 2017

    Hi,

     

    I dont have one right now, But will check if I can find one which can be shared. 

  • Beta
    Beta New Altair Community Member
    edited December 2017

    Hi,

     

    Is there any update about FATDEF load collector. Since I use MBD result for Fatigue, I have no idea on how to create a set of element to assign to FATDEF card. 

  • Altair Forum User
    Altair Forum User
    Altair Employee
    edited December 2017

    Hi @Toan Nguyen

     

    You can create elements set with the .fem or .hm file and use the same in FATDEF

  • Beta
    Beta New Altair Community Member
    edited December 2017

    hi, Thank you for the respond. But I got stuck right there. When I use ASSIGN/MBDINP to point to the .mrf file, it is required to leave my model BLANK. It means I can not create any element in model if I use MBDINP. If I try to do that, there will be an error message.  Since there is no element created, the set of elements could not be created also.  That makes me really confused. If OptiStruct doesn't allow me to create any element in model when use MBDINP, how could I define set of element for FATDEF and also for EL2PROP

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