Simulating biaxial rotation of mesh

40044600's picture
Submitted by 40044600 on Wed, 08/09/2017 - 09:36

I am having difficulties trying to simulate biaxial rotation of an imported mesh.

I am looking the simulate the motion which occurs during rotational moulding where the mould (mesh in this case) rotates around two of its axis.
The current rotation commands within LIGGGHTS that I've found allows rotation to be set to the coordinate system in space but not to the mesh itself, which is where my issue lies.

The primary axis of rotation (y-axis for example) can be set by using the coordinate system in space as this axis of rotation does not move during rotation. However, the secondary axis of rotation rotates with the primary axis and travels between the x and z axis (within the coordinate system in space) which I cannot achieve.

I hope what I'm writing makes sense to somebody as I'm at a lose how to achieve this rotation motion.
If it was possible to give the mesh its own coordinate system then it would solve my issue but I don't believe this is possible???

Anybody have any ideas on this?

Many thanks,
Jon

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j-kerbl's picture

j-kerbl | Thu, 08/10/2017 - 13:26

Hi Jon,

I see your problem and I do agree. It currently isn't possible to define this motion in LIGGGHTS-PUBLIC. This is a known issue and should be fixed within the next releases. The problem is, that regular move mesh commands do not update the axes.

Cheers,
Josef

40044600's picture

40044600 | Thu, 08/10/2017 - 14:14

hello Josef, thank you very much for response and confirming it currently isn't possible.

I'm wondering when you think the next release will be completed as I'm wondering if there's any point in me trying to somehow code this rotation motion now myself?

Thanks,
Jonathan

40044600's picture

40044600 | Mon, 10/09/2017 - 16:21

Hello Josef,

I wondering if there is any update on this?
Looking at the online documentation for the fix move/mesh rotate command (quoted below) it appears to describe the motion that I am looking for. I.e. the reference frame for the second rotate command moves with the rotation of the first rotate command. However, this is not what I'm finding is happening.

I'm hoping you can clarify this?

"Superposition of multiple fix move/mesh commands:

It is possible to superpose multiple fix move/mesh commands. In this case, the reference frame for the second move command moves along as the mesh is moved by the first move command etc. E.g. for style rotate, the origin of the rotation axis would be in local reference frame."

Many Thanks,
Jonathan