Cannot define CBUSH orientation

Burner2k
Burner2k Altair Community Member
edited March 2021 in Community Q&A

I've successfully used HM in the past (probably v14 or 2017) to define a CBUSH element with correct orientation. In 2020.1, I cannot get my orientation definition correct. A simple exercise, I created a surface which is at a weird angle to global axes & defined a line which is normal to the surface. Tried creating a CBUSH element using the end points/nodes...1D Panel -> Springs -> Create.

My understanding is that Node 1 & Node 2 define GA & GB respectively and it will be considered the default X-axis unless specified otherwise. I tried to create a orient vector using vector -> N1, N2, N3. Selected 3 end points/vertices of the surface (again my understanding is that plane defines the XY Plane or where Y vector will lie) and CBUSH is created. But when I try to review my orientation of the element using Orientation Review Tool, the axes of the element are aligned to Global principal axes. I even tried to create a custom coord where Y axis aligned with in-plane of the surface and defined the orientation explicitly using this system in CBUSH create/update panel...but still my element orientation aligns with global axes. 

I am not sure if I am doing it incorrectly or there is an issue with HM/HWX. I have to create lots of CBUSH elements on my model and hoping for an answer as quick as possible.

 

Another issue is that I was tried using Aerospace -> Connections -> Fastener Setup Tool to get HM/HWX create CBUSH elements but in my collector where I had around 20 lines defined, only 2-3 CBUSH/connectors were created. I believe I had defined the properties correctly...Just bringing it to attention...

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Answers

  • Julien Comas_21483
    Julien Comas_21483
    Altair Employee
    edited March 2021

    Hello,

     

    The review of the CBUSH orientation with the tool Orientation Review just after CBUSH creation is a known issue. We are working on that.

    Can you try something to confirm the orientation of your CBUSH:

    1-create the CBISH

    2-Define the orientation you want

    3-Export the CBUSH

    4-Import the CBUSH

    5-Check the CBUSH orientation with Orientation Review tool. The orientation should be correct.

     

    Regarding Fastener Setup tool, difficult to help you on that without more information. Maybe this is due to the tolerance defined in the tool. Can you give us more details?

     

    Thanks and Regards

    Julien

  • Burner2k
    Burner2k Altair Community Member
    edited March 2021

    Julien,

    Thanks for confirming the bug. I will try the process you've mentioned next week and get back here with results.

    Also any idea on ETA of bug fix?

    Also, wrt Fastener Connection Setup, what information is needed? The model I am working on is proprietary...so cannot post pictures or send it across. 

    I can provide the following information as of now:

    • The structure is metallic...with shell representation. The property cards were defined for all relevant elements.
    • I selected Huth Formulation with just CBUSH (no RBE3 or any rigids). I had created lines in HM between fastener hardpoints and all the lines I needed were in a separate container.
    • All relevant components connecting lines were selected. Some of the fasteners (in CAD model/per design) goes through multiple parts together. Had created different lines for each layer i.e. between each pair of sheets. For ex: If a fastener in reality goes through 3 different plates/sheets, in FEM, I had each line between plate 1-2 & Plate 2-3. 
    • Fastener material selected (with use material checked)
    • Diameter was asked to be calculated automatically (I did not select solid/component where the actual model with holes was located...could this be the issue?)

    As mentioned, please let me know what additional info would be needed to troubleshoot and I will check in my model & supply the same next week. 

  • Burner2k
    Burner2k Altair Community Member
    edited March 2021

    Julien,

    Sorry for the late reply. Anyways, to answer your question...

    HM "orientation review" tool seems to show the correct CBUSH orientation only if I define the CBUSH orientation using system during creation. However, if I used vector (N1, N2 & N3) method, tool does not show correct orientation (shows default global CSYS).

    If I export the solver deck and import it in to HM again and try "Orientation Reveiw" tool, it seems to show the correct CSYS orientation even if I have defined CBUSH orientation using vector method during creation.

    Hope the above helps and looking forward for fix ASAP. In my industry, CBUSH elements are essential and so is review of the orientation...

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