15 replies to this topic

[gruntguru]

3,000 hp @12,000 rpm ICE. 1,150 kg. https://newatlas.com...c87db5-90270322

 

 

Carbon con-rod, Ceramic piston, Generative design

 

 

Brake caliper.

[gruntguru]

I am dubious about the carbon conrod. Others have tried and failed.

[Greg Locock]

How about super-duper car? Or expialidocius car?

[Zoe]

Steam-punk inspired design.

[BRG]

Fantasycar, rather.  Although it would certainly be the fastest car ever built in Greece. 

[desmo]

These pieces kinda what I envisioned when CFRP first became a thing. Even a similar CF conrod. It turns out CF works best for larger, simple shapes with limited hardpoints, and that old-fashioned metals work better for the rest. Love to be wrong however, I'm left wondering how one "3-D prints" a fiber reinforced composite.

[Ross Stonefeld]

Did HR Giger design that piston

[gruntguru]

I have some components sitting on my desk printed in Markforged Onyx. (We have two Markforged printers that can use this material). It is chopped CF in Nylon. Generic versions of this material are available now and can be used in most cheap printers with the addition of a "hard" extrusion nozzle (Onyx is abrasive). I have been able to design and use components printed in Onyx for a wide range of engineering applications, Onyx being far stiffer than printable plastics.

 

The Markforged printers can also add continuous CF through a second print head which adds considerable strength and rigidity on 2 axes only. This is the obvious limitation of a printing process which uses what is essentially a "layered 2D" approach to build 3D items.

 

I am not au fait with the state of the art, but no doubt there is technology out there to print in "true 3D" using 5 axis print heads or similar. Such a machine would be able to print components like the brake caliper and con-rod pictured above and with CF oriented to stress.

Edited by gruntguru, 23 April 2020 - 22:08.

[Greg Locock]

Have you had a material test done on a finished component? Do the fibres align as they are extruded or are the material properties isotropic?

[gruntguru]

Haven't done a test. The chopped fibre components are somewhat anisotropic - bonding between layers is never as good as within each layer plus I suspect there would be some aligning of the chopped fibres during extrusion as you say.

 

When reinforced with continuous fibres, the components are highly anisotropic - significantly stronger in the build plane and similar strength perpendicular to it.

 

http://static.markfo...-data-sheet.pdf

Edited by gruntguru, 24 April 2020 - 03:44.

[JacnGille]

Did HR Giger design that piston

Or M C Escher????????????? 

[desmo]

Haven't done a test. The chopped fibre components are somewhat anisotropic - bonding between layers is never as good as within each layer plus I suspect there would be some aligning of the chopped fibres during extrusion as you say.

 

When reinforced with continuous fibres, the components are highly anisotropic - significantly stronger in the build plane and similar strength perpendicular to it.

 

http://static.markfo...-data-sheet.pdf

If I understand, each layer will have no reinforcing fibers shared with its neighboring layers so anything produced this way will have the same cleavage planes between the layers as unreinforced resin. Fine if you are making Star Trek-themed chess pieces; not so good for brake calipers or con rods.

[gruntguru]

Correct, but useful for components loaded primarily within one plane - struts, levers, flanges and so on.

[Greg Locock]

So you'd have to 'layup' along the load line? So in the conrod, start at the big end and traverse across to the little end? Wow, that's a detail I'd never considered. I'm envisaging one of those handheld plastic printers that look like pens, just weaving backwards and forwards like a spider. If you did that right you could actually run uniaxial through the nozzle as well, coated in resin. I bet that's been tried a million times.

[gruntguru]

Brake Lever at the bottom of this page is a good example.

 

https://markforged.com/mark-two/

[NRoshier]

looks like a printer I'd like to have, but a bit expensive for home use.