I have set up CNRBs at both ends of the box and applied rotation around the y-axis to these two nodes via the boundary prescribed motion node, I want to get to the moments at the two nodes. The help manual mentions that "prescribed motion" can only be done by implicit analysis, but my calculations appear to be" Nonlinear solver failed to find equilibrium."
Suppose I want to use explicit analysis, is there another way for me to apply rotation to the CNRB nodes
There's a couple options for applying rotation to CNRB nodes in LS-DYNA explicit analysis:
- *BOUNDARY_PRESCRIBED_MOTION_RIGID instead of _NODE:
- This can be applied to the rigid body (CNRB) directly
- Works in explicit analysis
- Define the motion using VAD (Vector of Angular Displacement)
- *LOAD_BODY_GENERALIZED:
- Can specify angular velocity/acceleration
- Works well with explicit analysis
- More stable than direct rotation prescription
- *LOAD_NODE_POINT:
- Apply moments directly to create rotation
- May need to carefully control the loading rate
- Use a combination of *DEFINE_CURVE and *LOAD_RIGID_BODY:
- Define the rotation curve
- Apply it to the rigid body
I would try the *BOUNDARY_PRESCRIBED_MOTION_RIGID first, as it's typically the most straightforward replacement for prescribed node motion in explicit analysis.
I want the reaction moments at the CNRB nodes, but as shown below, with the keyword BOUNDARY_PRESCRIBED_MOTION (including rigid), the reaction forces are only output to the dynain file in the implicit analysis
Okay so you have the rotation working correctly and now you just need to be able to extract the reaction moment? If that's the case, do you have the *Database_BNDOUT? That's the card you would need to be able to pull moment from either of those options I mentioned.
Thank you very much for your suggestion, after a series of numerical simulation attempts, I found that using BOUNDARY_PRESCRIBED_MOTION_RIGID outputs moment in the binout result, but if I use BOUNDARY_PRESCRIBED_MOTION_NODE there is no Result
