Learning Forum

[oumaimalahmar.ol]

hello

I model a 2d plate with two pegs (I presented them by 2 nodes where I blocked all translations).
the plate is hooked on the ground (concrete) so we wanted to make a modeling with springs, then the plate is in shell on which hangs springs modeling the concrete contact, then I used combin39 (according to z) for compression (I want my peg to work only in compression) and for shear I used combin 14 (according to x and y)

my problem is that my springs only work in tension, see the photo of the results:

there are the keyopt that I used :

Thank you 

[oumaimalahmar.ol]

@peteroznewman can you help me plz

[Rahul Kumbhar]

Can you please add your APDL code here?

[Sheldon Imaoka]

Hi oumaimalahmar.ol,

How are nodes I and J for your COMBIN39 defined?  Please note that positive displacement of node J relative to node I puts the element in tension, so maybe your definition of nodes I and J are flipped?  This can be sometimes tricky since nodes I and J are usually coincident, so please check which one you have as grounded (constrained) and which one is tied to the shells.

Regards,
Sheldon

[oumaimalahmar.ol]

hello @Sheldon Imaoka

thnak you for your answer.

by the way the nodes I end J are coincident, I have selected the nodes of the deck and I made copy the nodes, then I created directly element on the coincident nodes. 

[Sheldon Imaoka]

Hi oumaimalahmar.ol,

Is your node ordering (nodes I and J) correct?  You can try redefining the COMBIN39 if you are seeing tension vs. compression behavior to be behaving in a manner opposite to what you are expecting.  (Use EMODIF or you can delete and recreate the element, being sure to select the first node as node I.)

Regards,
Sheldon

[oumaimalahmar.ol]

hi  @Rahul Kumbhar

I used the interface.