PBEAR element of NASTRAN in OPtistruct

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

Hi

 

I need to simulate a bearing in Optistruct RotorDynamics. We have a PBEAR element in  NX NASTRAN for that .Do we have a similar kind of element in Optistruct .

If not how to simulate a bearing in Optistruct . 

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Answers

  • mpvnaresh
    mpvnaresh Altair Community Member
    edited July 2019

    Any ...clues 

  • mpvnaresh
    mpvnaresh Altair Community Member
    edited July 2019

    Any one please help me if any idea.

     

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

    PBEAR element type is not supported in HM-OptiStruct yet.However,Rotor dynamics is available in OptiStruct for modal frequency response, complex eigenvalue, static, linear direct transient and small displacement nonlinear direct transient analyses. Refer Optistruct online help for more details.

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

    Bearings can be added to the model which is typically connected to the stator using spring(CELAS) and damper(CDAMP) elements. Stiffness properties are added to the spring in the direction perpendicular to the rotor axial direction.

  • mpvnaresh
    mpvnaresh Altair Community Member
    edited July 2019

    Sir 

     

    Many thanks for the clues.i am modeling a bearing which is supposed to take radial loads and axial loads as well.

    How can i define  both the radial stiffness and axial stiffness  ? Is it by defining the nodes of the CELAS element in acylindrical CSYS? 

    Please guide me.

    If any example for bearing modeling  using CELAS is available .Please share.

     

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

    My above reply is in context of Rotor Dynamics with OptiStruct. For rotating components, additional forces like the gyroscopic force and circular damping force exist and are critical in the study of their response. It is important to determine these effects of rotating components on the system as a whole.

     

    The objective is to determine ,

    • Analyze steady state maneuvers of vehicles which have rotors.
    • Predict critical speeds and vibration frequencies for dynamic instability.
    • Calculate amplitudes of synchronous vibration caused by rotor unbalance.
    • Calculate frequency or transient response to externally applied synchronous/asynchronous loading.

     

    Attached some example for your reference.

     

    What is your end objective from the analysis?

    Unable to find an attachment - read this blog

  • mpvnaresh
    mpvnaresh Altair Community Member
    edited July 2019

    Sir

     

    Thanks for the reply.

    I understand you were talking abut Rotor dynamics .

    My objective is to analyse a motor under dynamic loads (Structural transient dynamics).Right now i dont bother about rotor dynamics.

    I need to simulate the stiffness of the bearing as it carries the  vibration load from the body of the motor to the rotor (or shaft).

    note: The vibration load is applied to the body of the motor at mounting locations as a base exciting acceleration.

     

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

    Since objective is to analyse a motor. Bearing simulation will add nonlinearity in to dynamic analysis.

    Bearing modelling is available with Altair Simlab. I remember there is one old script available in script exchange to provide bearing pressure.

    96363fb15afdba915aecee049fbe1756c50006b1

    Altair SimLab sT: Multiphysics product performance

  • mpvnaresh
    mpvnaresh Altair Community Member
    edited August 2019

    Sir 

     Thanks for the information. I dont have Simlab with me. 

    all i need to simulated with is only with optistruct .

    So It could be helpful if any thing related to bearing modeling using 0D elements like (CELAS and CDAMP elements) is shared.

    How to define radial stiffness and axial stiffness of a beareing with CELAS and CDAMP elements

     

     

    Thanks for the support and knowledge sharing .

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