closed lattice structure mesh in brep

Hi,

I'm a design student currently working on my graduation project. I'm very interested in Grasshopper but still a beginner so I would like to ask you questions and maybe get some tips as I personally don't know anyone who could help me learn this tool.

My ultimate goal is to achieve a lattice structure (for further 3d printing) of predesigned line cells filling the brep that can be modified with a use of attractor points. By closed structure I mean additional lines connecting the endings of struts trimmed with a brep. Ideally I wanted it to change desity (more smaller cells around attractor) and I tried with 'box packing" but without any good results (also the tool Intrallatice - btw very helpful and great tool - doesn't support any flexibility with grid). Maybe it would be easier to acheive if the structure was made from scratch but unfortunately I'm not really sure how to do that.

So after some time I decided to focus on struts thickness controlled by the distance from the attractor point (seems easier haha). I made a try with wireframe produced by Intralattice and both a mesh component from Intrallatice (1) and with a ExoWireframe(2)but they doesn't produce as satisfactory results as ExoWireframe on Proximity3D from random points (3) (which sadly is not what I'm trying to acheive). The scalling effect is not really visible and there are some problems with the mesh generated. ( images attached)

1 2 3

Maybe you could have a look at my files and at least tell me what is possibly going wrong? Honestly, I start to feel hopeless and it's such an important project for me.

P.S. It's my first question here but thank you all for contributing to this community, I've learned so much already by reading other discussions :)

Attachments:

Replies to This Discussion

Permalink Reply by Susan G on April 12, 2016 at 5:44am

I attach file with Intralattice wireframe baked for anyone who doesn't have this tool.

Attachments:

structure mesh baked wire.gh, 61 KB

Permalink Reply by Hyungsoo Kim on April 12, 2016 at 10:26am

Hi.

This is what I have got so far. Check attached definition.

You won't be able to increase the radius of strut whatever you want.

Attachments:

structuremesh_re(Exowireframe+Intralattice).gh, 39 KB

Permalink Reply by Susan G on April 12, 2016 at 12:25pm

Thank you so much for your reply! Seems like the answer was pretty close still I got lost haha. The Exowireframe solution is exactly what I needed :) The choice of radius is pretty limited sure, but it's because some of the lines are very short after trimming with brep, maybe I'll figure out later what to do with them or maybe just delete them.

Do you know any way I can "close" this wireframe? I mean by joining the endpoints of trimmed structure with lines so there won't be those protruding struts? I tried already a little with the closest point component but they were only finding themselves (probably still just a easy beginner problem :D )

Thank you again for your reply, I really appreciate it :)

Permalink Reply by Laurent DELRIEU on April 12, 2016 at 2:04pm

Hi,

if you want to solidify a structure with a mesh there are some other alternatives :

For the filling structure you could use some of the work done by Nik :

http://www.grasshopper3d.com/forum/topics/idea-with-bone

Meshing was done by Cocoon plugin from David Stasiuk. Nik also plugged tetgen (tehaedral generator, the equivalent of a mesh but for a volume not a surface).

If you want to keep small struts, Cocoon is the good option (here a chair). But if you want some fastest mesher, don't cut the wires and instead cut the mesh.

I could give you something to make BREP, but it is not fast for a lot of node.

http://www.grasshopper3d.com/profiles/blogs/yet-antother-node-gener.... I ran some of your examples and it worked with struts not cut. But it is a bit too heavy to use (2000 surfaces).

Permalink Reply by Susan G on April 13, 2016 at 7:45am

Hi Laurent Delrieu,

thank you so much for the info! Sorry for late reply but I was trying out the ideas and figuring out how to do it more efficiently. The bone structure by Nik is very similliar to mine but I cannot use it fully as Grasshopper just crashes (the files I provided here are just small test ones but really I'm working on a brep much bigger and with lots of struts). Although I'll try some more with it ( the bone structure is uniform but it will probably change if I want to make it more dense at some places?) and the Tetgen, it looks really promising but also confusing :D

The Cocoon plugin is pretty awesome and I saw your chair project before and it's great that you pointed it out as I also wish to achieve the look like this (with solid mesh from both sides and see-through in the middle). I would like to leave the inner structure as it is now because of the look (straight lines in cubes) also I finally found a way to increase its density in places I want so it's working fine the only problem is with the struts sticking out on sides. And because the struts are short in this structure after trimming they are getting really short and creating those awkward bumps:

Probably there are only two ways: deleting them or joining them together with additional lines. I tried with the method Nik used with the bone structure but only for the interseced lines with the side surface of brep to minimize the amount of points for calculation. It works but not great. I need to work more on adjusting the lenght of lines to be filtered out. I used Cocoon to thicken inner structure but I don't know how to achieve the "sandwich" look with the Cocoon like in the chair. And "glue" the filling with the top and bottom layers. Is it possible?

Here is what I mean by it:

Permalink Reply by Laurent DELRIEU on April 13, 2016 at 1:02pm

Here is the process :

I modeled the chair with some extrusions, quite very simple process. This shape is closed and has some holes.

The trick was to cut the lattice with a volume which is inside the volume. The yellow line above.

This volume, green on the above image

So with this there was an intersection with the Brep volume of the chair and the lattice.

After that I used cocoon. Here the parameters I used for the Brep and curve. So The Brep was offsetted.

The model is 80 unit height and cell size is 0.2 so roughly there are 400 divisions in Z. If cubic it will give 6.4 millions of cells. To my point of view it is important to choose well the cell size in order to have not hundred of million of cells. Here 6 millions was usable. The general thing with Cocoon is alwas to test it on small objects first.

A close view of mesh. Edge length is 0.1 unit. There are 6 millions of triangles.

Permalink Reply by Laurent DELRIEU on April 13, 2016 at 1:08pm

Here is the Cocoon script with chair model internalized. I deactivate the Cocoon.

Attachments:

cocoon.gh, 330 KB

Permalink Reply by Susan G on April 15, 2016 at 7:19am

Thank you sooooo much for your help! I'm really thankful for your detailed instruction now I am able to use Cocoon with a success :)

I still face problems with the struts sticking out from the sides. What did you mean by "But if you want some fastest mesher, don't cut the wires and instead cut the mesh."? Do you mean just meshing all of them and then trimming?

Permalink Reply by Laurent DELRIEU on April 15, 2016 at 8:50am

Excuse me I wasn't clear
Fast mesh could be done with exowireframe intralattice etc
As they don't work well with short struts I said to not cut struts with these tools. Do the mesh and cut the mesh at the end. More clear ?

Permalink Reply by Karan Khatri on November 13, 2017 at 11:55am

Hi Susan G,

I'm trying to make something similar to this!

It will be really helpful if you could tell me that how did you increased density in the area you desire?

Permalink Reply by Laurent DELRIEU on November 13, 2017 at 2:33pm

It just seems to be struts added/removed in some area.

For example you can use 2 types of lattice and the removes lines from one lattice were you want. After that you will have to remove duplicate lines. You just have to choose scale/lattice that allows lines/struts to connect.

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