Pre-loaded springs

jker
jker Altair Community Member
edited October 2020 in Community Q&A

Hello everybody,

 

is it possible to create pre-loaded CBUSH elements in Optistruct? 

I would like to model with spring elements braced components (tet-meshed) with a defined spring stiffness. The spring elements are attached by RBE3 to the component's surfaces (RBE3-spider -- CBUSH -- RBE3-spider).

My goal is to model pre-loaded human ligaments restraining the hip.

 

I'd be glad to get any advice on this topic.

 

Best regards 

Jo

 

 

Tagged:

Answers

  • Rahul Rajan_21763
    Rahul Rajan_21763 New Altair Community Member
    edited January 2019

    Since this is a biomedical part,it would be little difficult to comment on the modelling approach via Rbe3 and Bush element. In OptiStruct, we can run preloading analysis, however use of cbush would be limited.I guess pgap element should work here.What type of analysis you want to perform?

  • jker
    jker Altair Community Member
    edited January 2019

    Thank you very much for your quick response and excuse me for my basic questions, since I am new to Optistruct.

    In order to test different types of connection, I have created an basic model of an half hip that is attached to this post. It represents the basic idea and main challenges, which I would like to implement on a comlete human hip.

    In this model I am currently trying to work with CRODS and CBUSH to have the possebility of pretension.

    I have trouble with convergence due to not closing gaps and I think that might be because of the fact that there are just SPCs at the right component. I hoped by using pretension to close the gap that would solve that problem.

    What is your advice?

     

    Thank you so much for your help.

     

     

     

    Unable to find an attachment - read this blog

  • Rahul Rajan_21763
    Rahul Rajan_21763 New Altair Community Member
    edited January 2019

    Can you share the out file which has convergence issue reported.

  • jker
    jker Altair Community Member
    edited January 2019

    Attached you can find the out file

    Unable to find an attachment - read this blog

  • jker
    jker Altair Community Member
    edited January 2019

    I have just seen that in the model version is missing a force in y-direction with 750N in the load collector MC_Ace_Force.

  • Rahul Rajan_21763
    Rahul Rajan_21763 New Altair Community Member
    edited October 2020

    You also have two warnings in shared out file ,one is for high stiffness for bush and other one related to singularity.You can also refer to below post where i shared file for pretension of bolt with contact.

    https://community.altair.com/community?id=community_question&sys_id=fc5600f61b2bd0908017dc61ec4bcb6b

     

  • jker
    jker Altair Community Member
    edited February 2019

    Thank you for your help

Categories