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

 

 

 

 

 

 

 

 

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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

 

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tinh

Hi

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.

 

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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.