Coordinate system for spring element

[Salam88]

Hello,

I am using abaqus. Is there a way to define a local coordinate system which varies during analysis to reflect any deformation? This is for a spring element. I used "*Orientation, DEFINITION=NODES" but it did not work. Do I need to use subroutine?
Any help will be appreciated.
Thank you

Salam,

 

[FEA way]

Which type of spring (1,2 or A) and which type of analysis (standard or explicit) do you use ? Orientation can be defined for SPRING1 and SPRING2 elements. It can use local coordinate system but it’s assumed that this CSYS is fixed. Even in large-displacement cases the direction of action of these elements remains constant.

 

[Salam88]

Thank you for you repley
I am using spring type 2 nonlinear and standard analysis. So there is nothing I can do? I want the direction of action changing during the analysis and follow a certain nodes.

 

[FEA way]

SPRINGA element doesn’t have fixed direction (it just acts on the line connecting two nodes) so that its line of action may undergo some rotation during the simulation due to large displacements. I think that this is the only option to achieve your goal.

 

[Salam88]

In my situation, the spring force is not follow the line of action, The spring transfer a shear force.

 

[FEA way]

Can you attach a picture showing the definition of your spring (connected points in viewport and Edit Springs/Dashpots window) ? Or part of .inp file with this definition ?

An alternative to this approach with spring element is to use connector with elastic behavior. Maybe it will be better in your case.

 

[Salam88]

It is 2d as shown in attachment. Two beam connected by spring element. When beam deflect , I want spring force direction follow the deformation

*ELEMENT, TYPE=SPRING2, ELSET=elset_spring2
953, 40, 606
954, 80, 646
955, 120, 686
956, 160, 726
957, 200, 766
958, 240, 806
*SPRING, ELSET=elset_spring1, NONLINEAR
1, 1
** Force1, Rel. Displacement1
** Force2, Rel. Displacemnet2
**
-11.73,-0.073
-5.64, -0.02
0, 0
5.64, 0.02
11.73,0.073

 

[FEA way]

So this spring is between two nodes of beam elements and its line of action is in 1 direction, right ? Then it shouldn’t be a problem to use SPRINGA between these 2 nodes instead.

 

[Salam88]

Each spring has stiffness in 1 and 2 direction. Direction (1) has shear stiffness and direction 2 has axial stiffness. SpringA will be fine to represent axial stiffness. But it will not work for shear stiffness.

 

[FEA way]

Ok, I understand now. I'm afraid that connector with elastic behavior is the only option left in this case.

 

[Salam88]

Connector element does not work too because its coordinates rotate in a way make the shear displacement equal to zero. Thanks though

 

[Mustaine3]

I don't understand the question. If the spring rotates, so the line of action stay between the nodes, then there is no shear displacement. You can not have both things at the same time. At least not in one spring.