Hi all, I am working on cutting modeling. *BOUNDARY_PRESCRIBED_MOTION_SET is used to define horizontal motion and rotation speed of the disc. But the rotation motion is conflicting with translation motion.
I wanna the disc only moves along the -Y direction. But if I constrained the disc on the X and Z direction. The rotation will not work. Could someone give some suggestions?
Sorry I didn’t get back to you on this. That’s smart. So you just defined the translation in the plate instead of the circular part? You also should be able to define 6 different *Boundary_prescribed_motion_rigid on the circular part and define a linear Y motion and rotational y motion, and define a curve of no motion for the remaining boundary cards. This should allow the plate to spin and translate at the same time.
Sorry I didn’t get back to you on this. That’s smart. So you just defined the translation in the plate instead of the circular part? You also should be able to define 6 different *Boundary_prescribed_motion_rigid on the circular part and define a linear Y motion and rotational y motion, and define a curve of no motion for the remaining boundary cards. This should allow the plate to spin and translate at the same time.
Thank you very much for this. The point for my model is that the disc not a rigid body. So, there are conflicts for defining the translate and rotation simultaneously.
I selected some elements in the center of the disc to build a small rigid body. Then, using Boundary_prescribed_motion_rigid to defining translation and rotation for the small rigid body. The motion of the small rigid body will drive the outer disc moving.
Yes this is a common problem and that’s how you can solve it for sure. You could also model a rod-like rigid body that is nodally connected behind the disc and use that to drive the rotation of the disc. This would act the same but may be useful to keep in mind for future simulations where to don’t want a rigid body in the center of a deformable part.
This an excellent idea. Just as you described, in reality, the disc is driven by a roller. The rod-like rigid body is similar to the roller.
Another method is defining a joint in the centre of the disc, using Constrained_joint_revolute. Unfortunately, I am not master it yet.
It really just depends on the goal. If you add too much complexity like joints where you could just define a rotation then you may end up getting less reliable results.
And yes defining joints can get tricky.