Optistruct - No Separation contact simulation

Altair Forum User
Altair Forum User
Altair Employee
edited November 2020 in Community Q&A

Dear all,

 

I'd like to ask you for help regarding specific contact simulation.
Please have a look at the sketch below (I know that this particular case can be easily calculated analytically :)/emoticons/default_smile.png' srcset='/emoticons/smile@2x.png 2x' title=':)' width='20' /> ).

 

There is a L-shape profile (on the right) which is screwed in to a flange on the left.
There are two types of connection:

  • Pin connection - pins transmit shearing load (red)
  • Bolted joints which ensure flanges integrity (blue)

 

There is also a contact plane marked in yellow.

 

Example.png

 

I have modeled pins explicitly with merged nodes between flanges as shown on the figure below.

Example2.png

 

My question is how to model the contact between blue and dark yellow elements?
Ideally it would be kind of no separation contact so both surfaces remain fixed but no shear load is transmitted.
I want the pins to carry all shear load and I'm not interested in the bolts assessment.

 

There is a nice presentation about optistruct contact settings - 

And even contact type 'NOSEP' is described but I can't find it in my v13.

 

Could you please give me any advice?

Thank you in advance.

 

 

 

Unable to find an attachment - read this blog

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Answers

  • Altair Forum User
    Altair Forum User
    Altair Employee
    edited May 2016

    Hi Jakubat,

    if you use no separation contact, once the contact pair comes into contact, they can slide against each other without friction as you can read in the  file page 20. So if you use 'no separation' contact shear load can be transmitted, it depend only on your loading condition (see page 23).

     If you want  both surfaces remain fixed but no shear load is transmitted use FREEZE contact so that you will only transmit tension and compression. 

    Have a look on this : 

     

    Unable to find an attachment - read this blog

  • Altair Forum User
    Altair Forum User
    Altair Employee
    edited May 2016

    Hi GAYE,

    Thank you for your advice. 
    I slightly disagree with the last statement - FREEZE contact type transmits all kinds of loads/motions as its described in the help and the post you  mentioned. 
    If I use FREEZE type in my case there will be no point in modeling the bolts and pins. Glued surfaces are bonded and pins will not see any load at all.
    Just for confirmation - I'm speaking about vertical loads right now (vertical force/dead weight) 

     

    This means basically, that the two contact surfaces are 'glued' and will transfer all loads / motions between master and slave (also known as Tied Contact).


    My initial idea was to replace only the screws by the 'NOSEP' contact type. Just wanted to save time :)/emoticons/default_smile.png' srcset='/emoticons/smile@2x.png 2x' title=':)' width='20' />
    The problem is that I currently don't see any way to insert NOSEP contact in HyperMesh (Optistruct profile)

  • Altair Forum User
    Altair Forum User
    Altair Employee
    edited May 2016

    Hi jakubat,

    sorry for the misunderstanding, my advice was about the contact between  blue and dark yellow elements not about modeling  the pin and bolted :

    Example2.png

    And i was thinking initially that you have 2 bolted joints (red and blue) instead of pin and bolted here : 

    Example.png 

    GAYE

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