I have a problem simulating the preload of a series of bolts on a bracket.
I’m using point spring to replicate the presence of the bolts (I’ve add the stiffness of the bolt on the spring, and then applied a concentrated force to replicate the preload).
What I’m troubling is that all the springs are oriented along the positive X-axis, but in four (of six) cases I need to flip the direction of the spring.
Leaving the spring all oriented in the same way, but appliing the preload in the opposite direction, I’m not able to generate the stress on the bolt contact surfaces.
N.B. I removed the mesh to fulfill the max MB requirements of 10MB
Is someone that can help me?
This is a preliminary study of a bigger machine.. so I would like to implement the correct workflow on a simpler model and then moving on to the full assembly.
If you are using Point Spring implemented un PrePoMax, internally this is spring to ground element (SPRING1). There are also two other spring types that can be defined between two nodes abd have their direction specified by the user: Spring between two nodes
However, they require keyword edits. But they will give you more control over the direction/orientation of the springs.
Yes, it was a strategy that I would like to implement, but checking the Calculix Keywords I’m not able to find where is written the point sprig properties:
They are in the Constraints menu, but internally (in keywords) they are defined as finite elements so you can find part of their definition under Elements (*ELEMENT, TYPE=SPRING1) and the rest under Sections (*SPRING). If you want to use other spring types than node to ground, you should add them from scratch (nodes, elements and section properties). You can find more details and some examples on the forum and in the CalculiX manual.
Yes, look for *RIGID BODY keywords and their REF NODE and ROT NODE paramerers will point to the proper node numbers (ref node is for translational DOFs, rot node is for rotational ones). Since the nodes are already defined, you can use them directly when creating spring elements.
The simulation is running properly, but I’m not able to see any graphical reference that indicate the presence of the spring created? Is it true and there isn’t any way to see graphically the spring or am I missing something?
This creates a spring between ref node and rot node of the same rigid body constraint. These nodes are coincident and it’s not really what you want to achieve. You should either connect ref nodes of two different rigid bodies or one ref node to a new node where you can apply a BC/load.
2500 mm displacement ? Is something disconnected ? You can check by running a frequency analysis.
Regarding the GUI implementation, it’s on the feature requests list but it may take Matej (PrePoMax author) some time because there are many other requested functionalities and the ones particularly difficult to define via keyword edits have the priority.
