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Nahid3007

Create pin-joint Beam Analysis

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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

 


 


 


 


 


 


 


 


post-32609-0-34663900-1410975271_thumb.j

post-32609-0-88152300-1410975278_thumb.j

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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)


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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


 


post-32609-0-74786900-1411059410_thumb.p

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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)


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Aaaaaaahhhhhhhh, finally I solved this problem :D  :D .

 

 

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.

post-32609-0-85525500-1411128739_thumb.p

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