Mass assignment in 2D simulations

I would like to ask about the 3D model I created when I was modeling, but I wanted to do a 2D simulation, and suddenly I had a question. I have set as following:

Question:

If I do this, is this mass assigned to a 2D disk or a 3D cylinder?

Because I found that when I was modeling a cylinder, when the y-direction length was different, the reaction of the cylinder was different (the mass value did not change, only the y value during modeling was changed).

The y range of the box is -0.05 to 0.05


Option One:

The cylinder is basically stationary

Option two:

The cylinder begins to move rapidly.

I don't know if it's a side wall effect or a quality issue. is this mass assigned to a 2D disk or a 3D cylinder?

Comments

  • edited March 2022

    @Alex @Asalih3d

    Excuse me, can you give me some help or explanation for this problem?

  • @Alex @Asalih3d

    Can you give me some help or explanation for this problem?

    Thanks very much!

    Best regards!

  • Mass is assigned to the object to compute weight force.

    So you have to assign the actual value.

    Note that 2D mass is not equal to 3D mass....

    Mass(2D)=Mass(3D) / widthY

  • edited March 2022
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    Mass is assigned to the object to compute weight force.

    So you have to assign the actual value.

    Note that 2D mass is not equal to 3D mass....

    Mass(2D)=Mass(3D) / widthY

    @Alex OK, I think I have understand. Do as I did in the picture above, this mass is assigned to a 2D disk. But what I want to ask here is another question, Why do models built from 3D affect the simulation when I'm doing a 2D simulation?

    In the 3D modeling, the length of the aluminum rod is different, and the results of the simulation are different: in the first case, the y-coordinate of the aluminum rod is from -0.049m to 0.049m, and the simulation result is that the aluminum rod will not collapse. In the second case, the y-coordinate of the aluminum rod is from -0.01m to 0.01m, and the simulation result is that the aluminum rod will collapse

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