Where to buy Carbon Fiber Plates with full twill waves?

[Andres125sx]

Hi,

I´m searching for some site to purchase carbon fiber plates, but most of them sell carbon fiber where you can choose twill or plain wave... but only for the first and last layers, the rest are unidirectional non fabric carbon

I´ve usually purchased from R-G.de wich also sell twill waves outside and UD inside, and I´m happy with the results, but this time I need something as resistant as possible


Any help?

[Cold Fussion]

I'm not entirely sure what you need but this could possibly work

The specifications are listed as:

Specification
Laminate Composition
In 3mm thickness, this resin infused high strength panel is composed of the following carbon fabric layers:

• 200gsm 2/2 twill 3k carbon
  300gsm -45 Biaxial Carbon
  650gsm 2/2 twill Carbon
  200gsm 2/2 twill 3k carbon
  650gsm 2/2 twill Carbon
  300gsm -45 Biaxial Carbon
  200gsm 2/2 twill 3k carbon

In 2mm thickness, the sheets are composed of the following carbon fabric layers:

• 200gsm 2/2 twill 3k carbon
  300gsm -45 Biaxial Carbon
  650gsm 2/2 twill Carbon
  300gsm -45 Biaxial Carbon
  200gsm 2/2 twill 3k carbon

In 1mm thickness, the sheets are composed of the following carbon fabric layers:

• 200gsm 2/2 twill 3k carbon
  300gsm -45 Biaxial Carbon
  200gsm 2/2 twill 3k carbon

Resin matrix is high-performance epoxy throughout. Panels are post-cured at 70'C for maximum mechanical performance.

They don't supply a datasheet so you'd have to conduct your own strength testing.

[Andres125sx]

Yes that is!

But they only have up to 3mm, I need 6mm thickness or at least 5mm

But they have angles wich is interesting too, so thank you for the link anycase

[Cold Fussion]

6mm in pure cfrp is pretty thick, what are you using it for? They sell this panel which is is 2 layers of carbon twill with a pvc foam core.

[rscsr]

Yes that is!

But they only have up to 3mm, I need 6mm thickness or at least 5mm

But they have angles wich is interesting too, so thank you for the link anycase

Couldn't you just epoxy 2 pieces together?

[Andres125sx]

It´s for a racing drone I´ve designed... ok they´re not drones, but it´s the name everybody use so...

Usual frames are 4mm thick, but then they need to be very wide (poor aerodynamics) or thin and fragile. Add to this most frames use very poor quality CF, and I´m sick of breaking frames, so I´ve designed a frame wich is narrow to improve aerodynamics and thrust, but thick to improve resistance too.

Joining two panels togheter is doable, but resistance will never be as good since it´s not cured into a .... sorry don´t know the name in english.... I don´t think its called an oven? This would also require heavy sanding to reach the fiber so the resin really join the fibers, as if you join the plates directly it´s a smooth surface of resin with pretty poor adhesion

This is an example of the bashing these frames suffer. And now in winter we go flying at some parking lots with concrete all around so the bashing is even more severe


My design does include some dampers made of TPU from a 3D printer to absorb the first impact wich is what mainly break carbon, but I also need the best carbon I can find. I know it´s possible since I know some frame made of very good carbon, but can´t find their supplier

[Cold Fussion]

Is this FPV flying? I feel like for this sort of application you're probably better off with a carbon sandwich panel (one or two layers of carbon either side of a honeycomb core). You could make it yourself but to work with prepreg's you need a well controlled oven.

[jz11]

Couple thoughts:
There is a reason why they use UD inside, it is stiffer than weaved fabric, I think the use of weaved fabric for "core" will not make much difference over all.

If I understand the problem correctly, then those racing quads use 2 sheets of CF, bottom one is an X where motors are mounted on the pointy ends, and the top plate covers the middle of the cross to make up room to house battery/electronics, and the weak points are where the arms meet the central section, so if you want to avoid the CF shattering there, you might actually want to make it weaker and have a 90 degree twist in the arm, so it could flex and absorb sharp impacts from other directions than just vertical, that would require making custom moulds, but for starters you can use a metal strip, twist it by hand, and use it to vacuum bag wet CF on it, cut off excess and you have a part to mount on the central housing to do some crash testing, this way you may improve things at no weight penalty (which is important I assume, since those things are used for racing).

Also, cutting that X part out of a flat sheet and having interrupted strands going short distances across weak points of the design might be the main cause of the braking, so if you would make the mould for the X and lay the UD longitudinally on the arms (joined in the middle and sandwitched in between fabric layers) to make up the required thickness, things might improve enough to not need any other solution, I suspect that the UD fibers go across the weak parts of the "arms" weakening the structure, and if you use weaved fabric sheets, then the problem will still remain, just that the structure as a whole would have a little bit more flex in it before failure (thus masking the real problem).

[Andres125sx]

Is this FPV flying?

Yes, with quadcopters. I´ve been flying rc planes for the last 24 years, then fpv with planes and helis for around 10 years, and now fpv with racing drones for 2 years. And I must say these drones are a revolution like I had never seen before, before them rc flying was for us freaks who enjoy toy planes (they´re not toys, but that´s how people see them), but now with racing drones I know a lot of people who has never been interested on rc flying who is hooked to racing drones

I feel like for this sort of application you're probably better off with a carbon sandwich panel (one or two layers of carbon either side of a honeycomb core). You could make it yourself but to work with prepreg's you need a well controlled oven.

No way. Best of these drones is they don´t have any movable part apart from the motor bell. It´s all electronics, a flight controller where you solder 4 electronic speed controllers and 4 motors to these, that´s all, so on crashes they´re extremelly resistant.... but that means we abuse them too much and crash them hard and frequently. I crash around 5 times in average on a good day. On a bad one it may be 10-15 crashes and at the beginning they were slow, but now we can crash at 80-90 kmh with a tree, concrete column, metal pole...

So a sandwich panes is light years from being as resistant as needed. Heck I´ve broken so much 4mm solid frames I can´t count them. Actually I´ve just remind a friend of mine once purchased a frames wich was made of sandwich material. It was the lightest frame I´ve seen, but it broke at first flying day.

That´s the reason I´m looking for 6mm thick plates, same carbon section on a thicker arm is more resistant and also since it´s my design I´m not going to make holes at critical points as most manufacturers do and when it breaks, instead of purchasing one more frame, I can redesign the piece for reinforcement and send it to be cut

[Andres125sx]

Couple thoughts:
There is a reason why they use UD inside, it is stiffer than weaved fabric, I think the use of weaved fabric for "core" will not make much difference over all.

A little bit of flex is not bad at all, but I must say I´m a bit confused about what´s the best option. What I can say is the strongest frame I´ve seen to date is waved fabric the whole thickness, and the weakest chineese frames I´ve broken where UD inside. It may the carbon quality, resin or any other aspect of the manufacturing process tough...

If I understand the problem correctly, then those racing quads use 2 sheets of CF, bottom one is an X where motors are mounted on the pointy ends, and the top plate covers the middle of the cross to make up room to house battery/electronics

Yes, but to cover the electronics there are three options, what you said with a flat carbon plate over the electronics, or two vertical plates (my design) like this


This is the last frame I purchased wich has inspired my own design

And lately it´s becoming popular the pod option, policarbonate 1, 2 or even 3mm thick

But I don´t like it that much. I see people with pods breaking cameras much more frequently than myself with those vertical carbon plates

and the weak points are where the arms meet the central section

Exactly. Specially when manufacturers make some hole at that point, and they don´t reiforce the section

I´m convided they do it on purpose, they cannot be that useless

A good example, an arm of a light frame.... wich will not resist more than one or two crashes as much

so if you want to avoid the CF shattering there, you might actually want to make it weaker and have a 90 degree twist in the arm, so it could flex and absorb sharp impacts from other directions than just vertical, that would require making custom moulds, but for starters you can use a metal strip, twist it by hand, and use it to vacuum bag wet CF on it, cut off excess and you have a part to mount on the central housing to do some crash testing, this way you may improve things at no weight penalty (which is important I assume, since those things are used for racing).

That sounds awesome, but I don´t master carbon fiber manufacturing to that point, that´s the reason I stick with finished plates. Cutting my design on a flat plate is much easier

Also, cutting that X part out of a flat sheet and having interrupted strands going short distances across weak points of the design might be the main cause of the braking, so if you would make the mould for the X and lay the UD longitudinally on the arms (joined in the middle and sandwitched in between fabric layers) to make up the required thickness, things might improve enough to not need any other solution, I suspect that the UD fibers go across the weak parts of the "arms" weakening the structure, and if you use weaved fabric sheets, then the problem will still remain, just that the structure as a whole would have a little bit more flex in it before failure (thus masking the real problem).

Masking the problem is good, at least if it does prevent the frame from breaking apart

my design is mainly reinforcing the points where I need some hole, so the carbon section is the same with or without hole, and hopefully will resist much better than those poor designs

[jz11]

one thing I note in those pictures is the orientation of the strands (top layer at least), you basically get half the strength of the fabric just because of that, here is an example:


regarding the chinese composites, without analysis you cannot tell if they use dyed glass fiber in the middle or maybe CF with some cheap polyester resin, and even if they use epoxy, there is no telling if it was cured properly, each of these things may affect the strength of the product A LOT, and if they compound one shortcut on to another, then you get complete garbage as a result

there is no magic fix for this, going much thicker may give you a bit more life for that particular part (at the cost of added weight of course), but on the other hand - that shock energy doesn't go away when you crash it, if the bottom X survives, something else may not, cameras/electronics may develop problems, simply because that thick carbon part transmitted instead of absorbing it

what could be an option is to make the part from kevlar/cf mix fabric, if you can't make it yourself, ask someone who can, this mixed fabric will flex a bit more and may survive longer, but keep in mind the orientation of the strands in the parts when you cut them out from the sheet, the strands are orientated in 45/45 lengthwise of the X "arm", you could (and probably should) orientate each layer in 45 degrees to the previous, so when you look at the stack form above, you have not just X strand orientation, but like a 8 point star - this produces a little more waste, but will improve durability

basically - if you buy ready made sheets whichever fabrics are used, you cannot control the strand orientation, which is very important

p.s. not all epoxies are made equal, use quality stuff and if you use room temperature cure epoxies, do the post cure, if the epoxy doesn't come with the post cure data, pick another epoxy

p.s.s. plain weave and twill makes basically no difference in this context, picking one over the other may become important when you try to lay a complex shape, but for flat parts, it is basically the same thing

[Cold Fussion]

Excellent post. I think the key question is how weight critical is it? If you're willing to almost double the thickness purely for durability reasons then it suggests to me the weight isn't so critical and if that's the case, maybe considering making the arms out of E-Glass. E-Glass composites can potentially take 4-5x the strain of a CFRP part and the raw material costs will be on the order of 4-5x cheaper as well. You could design the arms as a sacrificial part in the event of an accident and just keep replacing them cheaply.

[Andres125sx]

one thing I note in those pictures is the orientation of the strands (top layer at least), you basically get half the strength of the fabric just because of that

I know, my first idea was that, cutting the arms with the fabric 45/45, but then I noticed when distributing the arms into the box wich is the carbon plate with 45/45 orientation I can only fit 10 arms per plate, while with 0/90 orientation they´re 14 so the price difference is noticeable. That obviously is the reason all comercial frames are cut with 0/90 orientation. I´m at that point now, that´s the reason I´m searching some site with quality carbon plates, because that depends on the fiber layout

regarding the chinese composites, without analysis you cannot tell if they use dyed glass fiber in the middle or maybe CF with some cheap polyester resin, and even if they use epoxy, there is no telling if it was cured properly, each of these things may affect the strength of the product A LOT, and if they compound one shortcut on to another, then you get complete garbage as a result

I know first hand, some didn´t have any stifness at all, bent like plastic arms, some delaminated at first impact, but they´re consistent on something, cracking easily

there is no magic fix for this, going much thicker may give you a bit more life for that particular part (at the cost of added weight of course)

I hope not, or not too noticeably. My idea is using same arm section to my last frame (the picture I posted) wich once I cut on proper carbon it was ok and they´re still surviving, but since the carbon will be thicker, the arm will be thinner. Same section, but with better distribution of the material to take the impacts on the vertical axis better, as that´s what always kill the arms. It should also improve a bit aerdynamics, not only reducing drag but also cutting down the thrust lost due to the prop airflow hitting a wide carbon plate 10mm down the prop

but on the other hand - that shock energy doesn't go away when you crash it, if the bottom X survives, something else may not, cameras/electronics may develop problems, simply because that thick carbon part transmitted instead of absorbing it

You missed the tpu printed dampers part the end of the arms and the top of the vertical plates will be more or less covered with TPU parts not fully solid wich will fit perfectly and will use the frame screws to secure in. The idea is to absorb part of the energy, prevent the carbon from receiving a sharp impact, and somehow limit the Gs at the crashes and limit the damage to the electronics. I know I know, I´m too optimistic

what could be an option is to make the part from kevlar/cf mix fabric, if you can't make it yourself, ask someone who can, this mixed fabric will flex a bit more and may survive longer, but keep in mind the orientation of the strands in the parts when you cut them out from the sheet, the strands are orientated in 45/45 lengthwise of the X "arm", you could (and probably should) orientate each layer in 45 degrees to the previous, so when you look at the stack form above, you have not just X strand orientation, but like a 8 point star - this produces a little more waste, but will improve durability

Carbon/kevlar would be awesome, and actually prices are similar, but it´s more difficult to cut, and I know the workshop I send the plates to be cut can cut 6mm carbon, but carbon/kevlar.... not sure, it´s risky

About the 8 point star distribution, I guess that´s what they say is quasi isotropic carbon fiber, full twill waves and alternating 0/90 and 45/45 pattern

I guess that´s what I´m looking for, but prices are a bit scary and can only find USA sites wich also add some custom charges

Also, quasi isotropic plates mean I can cut 14 arms per plate, while using cheaper carbon with UD core I should always place the arms with 45 degrees and can only cut 10 per plate, so probably there´s only one way to go

So the quesion is where to buy quasi isotropic 5 or 6mm plates in Europe

basically - if you buy ready made sheets whichever fabrics are used, you cannot control the strand orientation, which is very important

p.s. not all epoxies are made equal, use quality stuff and if you use room temperature cure epoxies, do the post cure, if the epoxy doesn't come with the post cure data, pick another epoxy

p.s.s. plain weave and twill makes basically no difference in this context, picking one over the other may become important when you try to lay a complex shape, but for flat parts, it is basically the same thing

That´s too much for me, with the design and infinite crash test procedure I have more than enough

I want to upvote your post!

[Andres125sx]

Excellent post. I think the key question is how weight critical is it? If you're willing to almost double the thickness purely for durability reasons then it suggests to me the weight isn't so critical and if that's the case, maybe considering making the arms out of E-Glass. E-Glass composites can potentially take 4-5x the strain of a CFRP part and the raw material costs will be on the order of 4-5x cheaper as well. You could design the arms as a sacrificial part in the event of an accident and just keep replacing them cheaply.

The arms actually are a sacrificial part in my design, they can be replaced easily

But glass fiber taking 4-5x the strain of carbon fiber? Really?

[Andres125sx]

Great explanation about quasi isotropic plates

https://dragonplate.com/ecart/categories.asp?cid=65


Any similar and hopefully cheaper site in this side of the atlantic ocean?