Filling body with lattices

[Garbean]

Dear PTC Community,

I frequently encounter the following problem and I can't wrap my head around it. I'd appreciate if some of you experts would like to shed some light into the situation.

I am trying to fill a portion of a component with lattice structures. I have separated the part to be filled as a separate component (you can find the part attached to this post as .prt, .igs, .stp). I am using Creo Parametric 9.0, and it only allows me to fill the part with formula-based lattices. When I try to fill it with beam lattices (e.g., hexagonal, see screenshot), I get a feature error. I also attempted to cut the body from a lattice cube using a Boolean operation, but without success. I tried this with many similar bodys, and can not get it to work properly.

Does anyone have a suggestion as to why this is not working?

My lattice Options:

Option for hexagonal beam lattice

Best regards,

Garbean

[Dale_Rosema]

Have you checked this out?

https://community.ptc.com/t5/Creo-Parametric-Tips/Did-You-Know-Creating-Lattice-Features-with-Creo-4-0/ta-p/820099

[Dale_Rosema]

after searching on lattice:

.... also:

https://community.ptc.com/t5/3D-Part-Assembly-Design/Creating-your-own-lattices/m-p/757282

[Garbean]

Thank you dale. I could not get it working with the shell method either, see my response below for further information.

[tbraxton]

This knife edge geometry is likely a problem. Try shelling out your model and then apply the lattice following the method that @Dale_Rosema posted.

[Garbean]

Thank you for your input. The Knife edge is crucial in this design and can not be avoided. I have, however, tried  the above mentioned method on a similar geometry that does not contain a knife edge without success. I assume this is the limits of the complex calculation required behind creating these lattices.

All the best,

Garbean

[Dale_Rosema]

I do not have a lot of experience with lattice structures, but could you initially stop short of the knife edge and after adding the lattices, add the knife edge back to the part? Just a suggestion.

[Garbean]

Thank you for your suggestion. The knife edge comes from a sweep, so I don't see a way to add it in later on. The knife edge sure is problematic, but it does not seem to be the main culprit here, as I can not perform the same action even on a similar body without the knife edge.

[ProFeature]

Is this checked in the cell's settings?

[Garbean]

A good idea, thank you for your reply. I have tried with the box checked and it ends the process without an error now. However, the result is not statisfying. Multiple lattices are missing.

I am coming to the conclusion, that this is a program limitation and the task is too complex to calculate because of the winding surfaces of the target body.

[YY110032788]

Hi @Garbean 

@tbraxton  drew your attention to the fact that you have knife-edge geometry, and you are drawing a (wrong) conclusion about Creo's capabilities.
Notice that you're attempting to fit a 3x3x3 mm grid into a space that can only hold 1.8-2.2 mm.

Furthermore, I don't understand why the lattice is required to reach the blade's tip rather than remaining a solid that maintains the entire geometry. Even assuming this is the design intent, I'm not sure how you'd print such a part with such a thick lattice, let alone the issues that would arise from adding the ball at the cell nodes. Judging by the geometry, this appears to be an academic activity.

I recommend that you discuss this with your supervisor.

[Garbean]

Hello @YY110032788,

Thank you for your response. You are correct in pointing out the knife-edge and the limited space for Creo to build the unit cells. I understand that this is not an easy task. However, it is not a problem for Creo Parametrics to construct formula-based unit cells within this constrained space.

I experimented with several different geometries that have less pronounced edges, but I still could not get it to work. I do not believe I am drawing the wrong conclusion here. In my opinion, the software should be able to cut out any portion of a lattice, no matter how thin. As I mentioned, I also attempted to cut it out of a block consisting of unit cells using a Boolean operation, but I encountered the same issue.

The above part will be integrated into another component and will be fully printable, even if only fractions of the unit cell occupy the space.