Opposite Force direction in bolts with the same load

Marius Wisser
Marius Wisser Altair Community Member
edited July 2022 in Community Q&A

Hello everybody,

I am an undergrad mechanical engeneering student and currently I am working on my bachelors thesis. In this process I ran into an problem with the simulation of a construction I have to analyse. Unfortunately I am not allowed to publich the whole model, so I reproduced the results in a MWE:

image

As the question title suggests, my interest lays in the bolts.

image

I modeled the connection using 1 RBE3 Element per hole and then connecting the RBE3s with an HYPERBEAM solid circle bar, which property is an PBEAM card. As orientation I used the y-axis, and i checked the elemental coordinate axes to face the same way. 

I used the ELFORCE Output card to display the forces in the bolts. On solving and reviewing the results, the magnitude is eaqual. Unfortunatly, the results for Element Forces in the y-direction is calculated as facing different directioins, but having the same absolute value:

image

Because of these results I can't really trust the simulation, because that seems highly unlogical to me. If anyone could help me out with this, I would be very grateful.

 

Kind regards

Marius

 

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Best Answer

  • Rogerio Nakano_21179
    Rogerio Nakano_21179 New Altair Community Member
    edited July 2022 Answer ✓

    Hi

    I think it happens because the two CBEAM are oriented in same direction.

     

    The end a or node N1  displacement/deformation relative to end b or node N2 is that is calculated.

     

    So for the two cbeam , in each of them, the end a moves in opposite direction relative to end b.

    Therefore, from the perspective of element result, the force is in opposite direction.

     

    To be clear, this is element force, it is not spc force. 

     

    I hope this is helpful

    Regards

     

Answers

  • Rogerio Nakano_21179
    Rogerio Nakano_21179 New Altair Community Member
    edited July 2022 Answer ✓

    Hi

    I think it happens because the two CBEAM are oriented in same direction.

     

    The end a or node N1  displacement/deformation relative to end b or node N2 is that is calculated.

     

    So for the two cbeam , in each of them, the end a moves in opposite direction relative to end b.

    Therefore, from the perspective of element result, the force is in opposite direction.

     

    To be clear, this is element force, it is not spc force. 

     

    I hope this is helpful

    Regards

     

  • Marius Wisser
    Marius Wisser Altair Community Member
    edited July 2022
    Rogerio Nakano_21179 said:

    Hi

    I think it happens because the two CBEAM are oriented in same direction.

     

    The end a or node N1  displacement/deformation relative to end b or node N2 is that is calculated.

     

    So for the two cbeam , in each of them, the end a moves in opposite direction relative to end b.

    Therefore, from the perspective of element result, the force is in opposite direction.

     

    To be clear, this is element force, it is not spc force. 

     

    I hope this is helpful

    Regards

     

    Thank you very much! That solved the problem!

    Now my ELForce in Z are orientated in different directions, but at least I can have trust in my simulation now.

     

    Thankfully,

    Marius

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