Manipulating N2S Contact Definition in Input File

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

Hi,

 

I am wondering if somebody could help me defining contact between to surfaces so that I can easily update the contact definition in the input file. 

 

The problem is stated as follows: I am pressing two beams together and would like to perform FRF modal analysis on the beams. With an optimization routine, I would like to update the contact definition between single nodes and surfaces to be either stuck, slipping, or not in contact, and match an experimentally obtained FRF. In order to solve this problem, I need to define the contact in a way that I can easily update the contact definition between single nodes and surfaces in the input file. 

 

In this initial analysis, I define the contacting interfaces to be stuck and am hoping to understand the input (.fem)  file, hoping to be able to figure out how tho change the contact definition from stuck to slide within the .fem file. 

 

Attached are the .fem file and the .hm file. Could you explain to me the entries in the .fem file in:

  • Line 61 (+          21603   13616   13929       1) 
  • Line 1762 to 1778: How is contact defined here? Is it between the sets of nodes? Can I change that to single nodes?
  • Is grid data the nodal position? Is CHexa Data the element definition?

 

I hope this description is sufficient to help me solve my problem. 

 

Thank you,

Kevin

 

 

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Answers

  • Altair Forum User
    Altair Forum User
    Altair Employee
    edited July 2017

    Hi,

     

    Altair Forum User said:

    Line 61 (+          21603   13616   13929       1) 

    Defines the element ID and grid IDs in the element contact surface created.

     

    Altair Forum User said:

    Line 1762 to 1778: How is contact defined here? Is it between the sets of nodes? Can I change that to single nodes?

    In your case it is defined between contact surfaces. You can remove elements which are not required.  G1Grid point identification number at the corner of the desired face of a 3D element. and the same with G2 which helps to indetify face for 3D elements.

     

    Altair Forum User said:

    Is grid data the nodal position? Is CHexa Data the element definition?

    Yes

  • Altair Forum User
    Altair Forum User
    Altair Employee
    edited July 2017

    Thank you Prakash,

     

    Changing to N2S contact conditions, can I manipulate the contact definition for every node in the input file? Is there another contact definition with which I can manipulate the contact between a single node and the in contact surface/element? Ideally, I would like to be able to go into my input file and change the contacts manually like:

     

    Node 1    Surface 1    Stick

    Node 2    Surface 1    Stick

    Node 3    Surface 1    Slide

    Node 4    Surface 1    Stick

    Node 5    Surface 1    Slide

    Node 6    Surface 1    Stick

    .....

     

    Thanks,

    Kevin

     

  • Altair Forum User
    Altair Forum User
    Altair Employee
    edited July 2017

    Hi Kevin,

     

    I don't think the nodes in slave/master can be done just by changing discretization method. Can you check if this scripts helps?

    <?xml version="1.0" encoding="UTF-8"?>ContactUpdate.PNG

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