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Create pin-joint Beam Analysis

Nahid3007

Hello community,

I have to do a beam analysis (see figure_1) but I don't know how to create a pin-joint in HyperMesh.

I have tried to use the joints panel in the 1D main menu page. Then I have selected the revolution joints type, because this joint type will constraint 5 dofs and will leave one rotational dof open.

This is exactly what I want. I have selected the two terminal nodes [Grids 5 and 6 (1000;0;0)] and switched first orientation vector to z-axis (figure_2).

But it did not work because when solving the problem there is an error message:

*** WARNING # 312

In static load case 1

the compliance is negative or large 2.545087E+11

Optimization/buckling analysis cannot be performed

due to possible rigid body mode

What did I do wrong? Or is this not the right way to create such a pin-joint for this type of analysis?

Thanks in advance

Nahid

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

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tinh

Hi,

To release any pin dof => enter it in to 'pin a =', 'pin b =' (panel 1D>bars). don't need to use joint

be careful about coodinate system of these dofs (element system)

and the left portion of your model seems to be freely moved for a while, so the message appearred to caution that something freely moving (rigidbody moving)

Nahid3007

First of all, thank you very much for the approach tinh.

I tried to use this. Since I only want to release the dof around the z-axis, I have pinned the nodes as depicted in the attached figure. I set the orientation to y-axis.

But I do not get my expected results. Did I understand something incorrectly?

Thanks in advance, again.

Nahid

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

tinh

is right constraint '12345'?

if it can move along x, the frame is 'provisionally transformable'? (actually i don't know how to call this status in english, sorry)

Nahid3007

Aaaaaaahhhhhhhh, finally I solved this problem .

I do not know why but the PLOAD1 is wrong somehow (this is really bitter ). I changed the distributed line load q into nodal forces (see attached figure).

Now I get my expected results. The FE results match perfectly with my analytical results.

Nevertheless, thank you for the efforts tinh.

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

Nahid3007

OK ... it also works with POLAD1 if I enter the right magnitude^^.

It has to be 2500 instead of 10 for POLAD1. Then I will get the exact same solution.