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
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
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.
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.
We have found a way to implement the SPRING2 elements. However, the process is very labor-intensive:
First, one must define the node sets on each “attachment” surface of the spring;
Then, it is necessary to define reference points associated with each node set;
These reference points must be connected to the node sets using rigid bodies;
Meshing must be performed, and only after meshing (thus having the ID associated with each reference point), it becomes possible to insert the SPRING2 keywords.
You can understand that in a simulation involving more than 100 springs, this becomes extremely tedious. @FEAnalyst, are there any plans for implementing SPRING2 in the graphical interface?
I would like to revive this feature request - right now, PrePoMax checks almost all requirements to be used in the company I work in, but one of the few remaining is the capability of creating springs between two nodes directly in the GUI.
I kindly appreciate all the support and updates provided for this amazing software.
maybe create line element between two nodes more appropriates and general ways. Line sections can be spring (linear SPRING2 and nonlinear SPRINGA), gap element (GAPUNI) or beam and truss element (linear B31, B31R and T3D2).
I add to the petition. Of course I understand how busy the developers could be, and always thinking that this is open source software with no economic benefit. I have an idea: from some years ago, I have seen Crowdfunding platforms (https://www.gofundme.com/ for example) and I think could be a great idea to get founds for the development of the project. A lot of companies and institutions could be interested on the development of the software and earn thousends of Euros.
I guess that Matej’s time as the only dev is the main issue here even regardless of sponsoring which was suggested in the past and is always an option (FreeCAD has multiple ways for that).
The best help would be writing some simple pieces of code and submitting them as PRs. I try to do that even though my coding skills are really poor. However, this particular feature is on the top of my list of rather simple features I could attempt implementing myself.
Let’s also highlight that Matej prioritizes features that are hard to define with custom keywords (which makes a lot of sense) while this FR is rather simple to add this way.
I agree with the desire for an axial spring between two nodes. I would further suggest that an element or constraint that allows for the specification of independent 6 DOF stiffnesses between two nodes would be quite useful, such as the Abaqus-type cartesian/rotation connector.
Currently, you can use 3 springs for translational stiffnesses. There are no rotational springs in CalculiX and they require rather tedious workarounds with rigid body constraints. Anyway, this would be a request for the solver itself. You can ask here: https://calculix.discourse.group/
