Spring between two nodes

[FEAnalyst]

In CalculiX there are three types of spring elements:

• SPRING1 - between a node and a ground
• SPRING2 - between two nodes, acting in a fixed, selected direction
• SPRINGA - between two nodes, acting along the line joining the nodes

In the current version of PrePoMax there is a point spring and surface spring constraint available. Both use SPRING1 elements and thus can be utilized to apply springs between nodes/surfaces and ground. It would be nice to also have a support for the remaining two spring element types so that two regions can be connected with springs. Here’s an example from the CalculiX forum: Spring between two nodes - CalculiX

[Hyp]

Hi,
I would also like to have that feature to be implemented.
Right now I am doing this with following keywords in the “Elements” Section:

*ELEMENT,TYPE=SPRINGA,ELSET=SPRING
99999,22750,22752 **Element Number, first Node or reference Point, second node or reference point
*SPRING,ELSET=SPRING
20. **constant spring stiffness in N/mm

Thanks a lot in advance!
Christian

[MikeCats]

I agree with you, it would be very useful to implement SPRINGA and SPRING2 elements in the GUI.
Any idea how to implement SPRING2 command? I read the Calculix help, but I didn’t find out how to specify the direction of the spring.

Thanks a lot!
Mike

[FEAnalyst]

Check the *SPRING chapter in the CalculiX User’s Manual:

For SPRING1 and SPRING2 elements the degree of freedom in which the spring acts is entered immediately underneath the *SPRING card.

Second line for SPRING1 or SPRING2 type elements:

• first degree of freedom (integer, for SPRING1 and SPRING2 elements)
• second degree of freedom (integer, only for SPRING2 elements)

[synt]

in addition, maybe it can be extending to Gap element also. A modeling approach using center and edge nodes to generate element such as spider beam in bolt connection can be useful.