Mass addition in master element of Type 2 contact

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

Hello everyone,

Greetings!!

 

I have made seam weld elements between 2 components. Then I made tied contact (Type 2 contact) between these components by considering seam elements as master component.

But when I ran the crash simulation mass of 720 kg was added in these seam elements, which made the entire mass of my crash sled 3.5 times heavier than the actual  weight.

 

image.png.0fa5d70ae927b7b06b7073eeda47b4ef.png

 

I have to use tied 2 contact as I wanted to use the contact interface for spot welds.

I cant omit DT/NODA/CST, otherwise my simulation time is increasing exponentially.

Because of crash simulation, some elements are deforming to a very small length.

 

Thanks in advance.

 

Regards

Nitin Jain

 

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Answers

  • Altair Forum User
    Altair Forum User
    Altair Employee
    edited March 2019

    Hi Nitin jain

       When you create a spot weld using type 2 spring in seam,  by default you will get the (TYPE13 spring property + TYPE2 contact).Please do change the values of parameters as per  your model unit system.

  • Simon Križnik
    Simon Križnik Altair Community Member
    edited March 2019

    @Nitin Jain

     

    type 2 tied contact interfaces with spotflag=1 will add mass. From Radioss help:

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  • Altair Forum User
    Altair Forum User
    Altair Employee
    edited March 2019

    Thanks @Pooja S 

    I am using Hexa (tapered T) type seam weld and I gave desired properties to it.

     

     

    Thanks @Ivan

    I ran the simulation again with switching off Spotflag. It solved my problem.

    But is my contact now simulating the exact condition of  spot weld or not.

    Because from Altair manuals, I learned that Spotflag=1 represents the condition for spot welds, etc.

     

    How accurate are the results with Spotflag= off.

     

    Thanks and Regards

    Nitin Jain

     

  • Simon Križnik
    Simon Križnik Altair Community Member
    edited March 2019

    The slave nodes height with respect to the master segments should be as small as possible. Indeed, the geometrical concordance is necessary for Interface Type 2 to work normally, and will help to get a lower added mass. Please go through the FAQ in Help Menu on Kinematic Conditions where this is well explained.

    Using fully integrated elements in combination with spotflag=0 is OK, but rotational DOFs are not transmitted. 

     

    Check the attached documents for details.

    Unable to find an attachment - read this blog

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