## LS Dyna

#### Explicit dynamic analysis for rotary broaching

• CJSmith
Subscriber

Hi,

To be frank, my heart is broken trying to set up this analysis.

In am attempting to look at rotary (wobble) broaching in explicit dynamics. Its a machining process that requires complex tool movement. As in, the entire tool moves linearly Z while the shank of the tool runs a circular pattern (not rotation) around Z while the face is fixed along Z. Apologies, my description is poor enough, it may be worth a quick YouTube view.

I slowly mocked it up in explicit dynamics, adding velocity, fixed support etc, but once I add the displacement of the tool shank (to create that circular pattern), it flags a "Could not transfer loads and constraints to the solve" error.

In short, my question is, is it possible. (I assume it is but Ive just not spotted my error)

All the best,

C

• CJSmith
Subscriber
Apologies for the vague question. The above is my tool displacement plot, with an additional displacement holding the tool face in Z. It moves perfectly in static structural mock up, but when I bring it into the explicit dynamic space. No joy.
If anyone has any insights, i would be greatly appreciated.
All the best C
• muqing114
Subscriber
Try Remote displacement
• CJSmith
Subscriber
Hi Muqing114
Thanks for the advice and apologies for not getting back sooner.
I've tried that too, no joy. I'm trying combined velocities at this stage, might give me some results. Maybe.
All the best C
• Chris Quan
Ansys Employee
For the same geometry entity, only one displacement/velocity boundary condition can be applied.
Suggest you using a single Velocity or Displacement boundary condition to describe the tool motion. Tabular data or Functions can be used in the definition of the boundary condition to describe such motion.
For example, you can add the tool displacement in X/Y/Z of all boundary conditions together from the solution of the Static Structural system and then apply them in Explicit Dynamics system as Tabular Data.
• CJSmith
Subscriber
Hi Cxquan Thanks for the reply, I have been trying to use two separate displacements to describe the motion up to this point. I'll need rethink the setup as the tool is in all sense tumbling, (there is two distinct patterns at each end of the tool)
Having I understanding it that I could link an explicit dynamic system to the solution of the static structural solve in workbench and move from there? Or simply use the same displacement plot.
I tried a solve with XYZ tabular velocity and a constant velocity in XYZ, which has given some results but over a single step.
My lack of experience in explicit dynamics is killing me.
• CJSmith
Subscriber
Apologies, Is this the static to explicit link you meant.
Thanks again for the reply Best regards
C
• Chris Quan
Ansys Employee
Since you mentioned that two displacement BCs work in Static Structural system, you can plot the total displacement of the tool and export the displacement to an excel sheet.
Then in Explicit Dynamics system, you can create a single displacement BC and apply it to the tool, then copy the X/Y/Z displacements from the excel sheet to the displacement (tabular) BC.