Brittle thickened resin

Talk Composites - The Forum for Advanced Composites

Back

Home
»
Advanced Composites Forum
»
Projects
»
Motorsport, Vehicle Design and Modification
»
Brittle thickened resin

Brittle thickened resin

Author	Message
Frank	Frank posted 6 Years Ago Topic Details
Group: Forum Members Posts: 27, Visits: 123	Hi I made a carbon front fender for my Husqvarna 701 Supermoto in a four part mould. The part of the mold that depicts the assembly area is cast from polyurethane. I fill the mounting area of the front fender with a thickened resin before vacuuming. I use about ¾ teaspoon chopped carbon fibre strands on 65 g of resin. The result looks neat, but the assembly area is more brittle than I expected. It sometimes breaks when I drill it. I am afraid it will break in rough use. If possible, I do not want to build a new mould. Any suggestions? Regards Frank
	Reply Like 1
Hanaldo	Hanaldo posted 6 Years Ago HOT Post Details
Group: Forum Members Posts: 2.5K, Visits: 28K	It's a nice approach, I like it. Are you vacuum degassing the cast section? It looks like it is full of air bubbles, which will drastic lower its strength.
	Reply Like 2
Frank	Frank posted 6 Years Ago Post Details
Group: Forum Members Posts: 27, Visits: 123	+x Hanaldo - 12/24/2018 9:46:38 AM It's a nice approach, I like it. Are you vacuum degassing the cast section? It looks like it is full of air bubbles, which will drastic lower its strength. Hi Hanaldo. No, I did not degass it. I mixed the chopped strands into the resin after mixing the AT30 in it. Frank
	Reply Like 1
George Sychrovsky	George Sychrovsky posted 6 Years Ago HOT Post Details
Group: Forum Members Posts: 24, Visits: 1.6K	+x Frank - 12/24/2018 10:25:29 AM +x Hanaldo - 12/24/2018 9:46:38 AM It's a nice approach, I like it. Are you vacuum degassing the cast section? It looks like it is full of air bubbles, which will drastic lower its strength. Hi Hanaldo. No, I did not degass it. I mixed the chopped strands into the resin after mixing the AT30 in it. Frank I would make a separate angle like carbon part and then bond it in , --------------------------------------------------------------------- Disclaimer opinions of others will vary depending on what they are selling
	Reply Like 2
oekmont	oekmont posted 6 Years Ago HOT Post Details
Group: Forum Members Posts: 550, Visits: 27K	I absolutely agree with George here. But now, that you are already at this point, let's see what we can do. Would it be possible for you to push a little bit of carbon cloth inside the chopped strands? To give the something to hold on to? Carbon Fibre putty has a really bad fibre content, and when working with it, it often arranges most fibres in one direction, leaving it almost unreinforced in the other directions. That and the high air entrapment makes it very brittle. If no cloth, maybe you could get at least some roving or long strands in there. Or you just saw the part off, bond an angle to it, and maybe use four rivets. That would likely be the toughest solution.
	Reply Like 2
f1rob	f1rob posted 6 Years Ago Post Details
Group: Forum Members Posts: 237, Visits: 4.8K	What george said is probily the easiest an best idea With composites you design the part for your material not copy your part in your chosen material. Not perfect but if you did want it in one operation,no bonding additional bracket,split your mould through that feature. With the two parts of the mould One ply front an rear rear both running into the feature. Put localised reinforcements in the feature to fill it Bolt mould together an do the rest of your plies as whole plies for the complete item
	Reply Like 1
Frank	Frank posted 6 Years Ago HOT Post Details
Group: Forum Members Posts: 27, Visits: 123	@Hanaldo: With the next Part I will try to degas the resin-chopped-strand-mix. @ George Sychrovsky : Yes, it would be the best way, to build a new mould and to design the mould for parts made of reinforced resin. But the mould is already made the way it is. And I already produced a useable Part in it. So, the job is done and the bike has its Carbon-Front-Fender made of CF looking nice. I do not want to build a complete new mould. Perhaps I can change the mould-part that is made from polyurethane. 1) I probably can design it to leave a flat area in the mounting-section of the Front-fender, to which I can bond an angle and the tubes made of CF. 2) Another way would probably be, to drill a hole in the PU-Mouldpart, pull the Vacuum through this hole and feed the resin from both small ends of the mould. @oekmont: Next time I will try to bring more reinforcement into the mounting-section and degas it. @f1rob: I agree to this. I just copied the part. Perhaps option 2) can help with that. I have to think about it. Regards Frank Edited 6 Years Ago by Frank
	Reply Like 2
Frank	Frank posted 5 Years Ago Post Details
Group: Forum Members Posts: 27, Visits: 123	+x Frank - 12/26/2018 12:32:43 PM @Hanaldo: With the next Part I will try to degas the resin-chopped-strand-mix. @ George Sychrovsky : Yes, it would be the best way, to build a new mould and to design the mould for parts made of reinforced resin. But the mould is already made the way it is. And I already produced a useable Part in it. So, the job is done and the bike has its Carbon-Front-Fender made of CF looking nice. I do not want to build a complete new mould. Perhaps I can change the mould-part that is made from polyurethane. 1) I probably can design it to leave a flat area in the mounting-section of the Front-fender, to which I can bond an angle and the tubes made of CF. 2) Another way would probably be, to drill a hole in the PU-Mouldpart, pull the Vacuum through this hole and feed the resin from both small ends of the mould. @oekmont: Next time I will try to bring more reinforcement into the mounting-section and degas it. @f1rob: I agree to this. I just copied the part. Perhaps option 2) can help with that. I have to think about it. Regards Frank For the last front fender, I did not fill the mounting area with chopped carbon fibre thickened resin as usual, but rather with dry carbon fabric. Just as the rest of the mold in the vacuum injection process. With a decent result. The mounting area was completely infused with resin during the infusion and is now just as stable as the rest of the component. Picture will follow... here it is: Regards Frank Edited 5 Years Ago by Frank
	Reply Like 1