FE Wood splinters workflow

[georgeivan]

Hi,anyone knows how to make bursting splinters using FE?

the default preset breaks the object in a sort of Voroni ugly pattern,you can change the frequency but still looks ugly

The 13mov have a very cool scene about this,but i wonder if they drive the highres with a proxy ,if that so,i cant figure the workflow to drive highres objects.

looking at the FE preset the cuts are done in attrib_fracturepart with a voroninoise.

But i wonder what its the best approach

Thanks!

[Milan]

The simplest way of getting splinter like behavior is scaling you geometry down on one axis before the tetrahedralizing and scaling it back up after the fracturing. That should give you nice long and thin pieces.

[Sierra62]

As milan suggested scaling in one axis is great for getting high res splintering. Using your scaled geometry and embed it into a normal fracturing geometry. The finite element will have less errors with regular shape tets, than stretched out tets.

[Sierra62]

Other general tips to get that look in the H13 videos; set the volume mass density to 750. If it is interacting with other objects in the scene, you need to set the global substeps to at least 3. For look development, run your tests without self collisions, once you like what you are getting, turn on self collisions and enjoy the large sim time. I also recommend writing your file out prior to the tetrasurface node, that way you can use the new points to emit dust or other debris from. Remember to have it tetrasurfaced prior to rendering.

[georgeivan]

Thanks Milan,will try that

Thanks Cody very good tips!

Edited November 6, 2013 by georgeivan

[georgeivan]

Well tried the suggestions,looks nice.

How can drive a more detailed geo with this sim?

i got some errors about badly shaped tets when calculating forces,must be related to scaling maybe or the fact i put 10 to max substep(it takes forever here,just testing if i can speed up things)

hey Cody! its your work on the sneak peek? pretty awesome!

WoodFE.hip

Edited November 6, 2013 by georgeivan

[Sierra62]

Ya that was my work on the sneak peeks, thanks a lot.

I have taken your file and changed things around for a better result.

Finite elements is not meant to used for quick simulations. It does very accurate fracturing and deforming. There are some ways to get better performance, but it does sacrifice the end look, also it increases the chance of inverting some tets.

in the file I put some notes to explain some of what I did. I got rid of the remesh node; personal preference.

Let me know if you have more questions.

WoodFEM_tweak.hip

[georgeivan]

Thanks Cody!,very kind,I hope to return the favor at some point,thanks!

[bandini]

Thanks for the file. Very instructional.

One question: Is there any way to make fully rigid solid objects? Even with my strength values cranked super high, they still look jelly-like. I have stiffness set at 20,000,000 and the objects still bend when colliding with something.

[Sierra62]

To get a stiffer object it also takes into account the overall damping. I would try raising the overall damping ratio. Also the Volume mass density can help too.

[bandini]

I have the overall damping set to 10. Not sure if going above that is recommended, based on the slider limits. Since this is supposed to be based on real structural models, it would be great to know what some values for commonly used materials are. Maybe someone at SideFX can think about adding some presets into the next build?

Cody, if you have a simple file of a non-fracturing piece of wood dropping onto a cube, and not warping (built to real-world scale), I would love to see the settings.

[Sierra62]

To control the stiffness of the object, I got the best results by changing the anisotropic strength. Attached is a file with a very stiff board. I hope this helps.cheers,Cody

WoodFEM_Solid.hip

Edited November 7, 2013 by Sierra62