STATSUB (PRETENS) vs STATSUB (PRELOAD) vs PRETENSION- OptiStruct

Neeraj Kumar
Neeraj Kumar Altair Community Member
edited May 2022 in Community Q&A

Can somebody please explain me the difference between STATSUB (PRETENS), STATSUB (PRELOAD) and PRETENSION in subcase definition?

Thanks.

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Best Answer

  • PaulAltair
    PaulAltair
    Altair Employee
    edited May 2022 Answer ✓

    PRETENSION is used in the case where you are initially applying the bolt pretension, it calls the PTADD or PTFORCE,PTADJST etc for the bolts

    STATSUB(PRETENSION) is used to use a previously run PRETENSION case to load another analysis (Linear and Non-Linear Static only) it can be called in addition to further PRETENSION if needed to create a bolt tightening 'sequence'

    STATSUB(PRELOAD) may also call a previous subcase including pretension but may be used for a wider range of subsequent analyses (e.g. normal modes, frequency response)

Answers

  • PaulAltair
    PaulAltair
    Altair Employee
    edited May 2022 Answer ✓

    PRETENSION is used in the case where you are initially applying the bolt pretension, it calls the PTADD or PTFORCE,PTADJST etc for the bolts

    STATSUB(PRETENSION) is used to use a previously run PRETENSION case to load another analysis (Linear and Non-Linear Static only) it can be called in addition to further PRETENSION if needed to create a bolt tightening 'sequence'

    STATSUB(PRELOAD) may also call a previous subcase including pretension but may be used for a wider range of subsequent analyses (e.g. normal modes, frequency response)

  • Neeraj Kumar
    Neeraj Kumar Altair Community Member
    edited May 2022
    Paul Sharp_21301 said:

    PRETENSION is used in the case where you are initially applying the bolt pretension, it calls the PTADD or PTFORCE,PTADJST etc for the bolts

    STATSUB(PRETENSION) is used to use a previously run PRETENSION case to load another analysis (Linear and Non-Linear Static only) it can be called in addition to further PRETENSION if needed to create a bolt tightening 'sequence'

    STATSUB(PRELOAD) may also call a previous subcase including pretension but may be used for a wider range of subsequent analyses (e.g. normal modes, frequency response)

    So that means, the output results of the PRETENSION case, will be used as input (initial condition/state) for the STATSUB(PRETENSION) [ or STATSUB(PRELOAD) ] loadstep?

  • PaulAltair
    PaulAltair
    Altair Employee
    edited May 2022
    Neeraj Kumar said:

    So that means, the output results of the PRETENSION case, will be used as input (initial condition/state) for the STATSUB(PRETENSION) [ or STATSUB(PRELOAD) ] loadstep?

    Sort of, yes and no! None of these describe a case or step exactly

    the 'PRETENSION' isn't a 'case' as such, it is a card within a step, (like a load or SPC), it is part of the definition of loading of the initial step (lets call this loadstep 1)

    the STATSUB (PRETENSION) (or PRELOAD) isn't a step that you run either in and of itself, rather, again, they are cards within a step that provide a callback to a previous, separate step (containing that pretension, e.g. this could be your loadstep 1) that is used as the initial condition for the subsequent step (loadstep 2) and that 2nd step that may itself contain PRETENSION (that is loading of other bolts or adjustment of existing ones)

    So: to further clarify, your STATSUB(PRETENS) card (within a step) is calling/referring to the case where you ran with PRETENSION as a loading

     

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