After 3 fails its time to ask where i go wrong..


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jeffrey bres
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As mentioned..   3x not a charm here.

I have this isseu every time.
Clearcoating without gelcoat would be an option. But allso that isnt easy with small holes like this.

Now i used gelcoat. Hoping it would help.

Gel had cured at 25 degrees for 5 hours was dry to touch.

I used 3m high tack clear spray adheasive to hold the fibers in place. (AS LITTLE AS POSSIBLE)


on the vacuum catch pot the dail says my vacuum is 100%
I leace the pump running over night.  In the morning when the resin is hardned the vacuum line form the ez composite starter kit to the pot is flat from the vac. 

(I dont have an official cacuum pump.  I use a 35l/m fridge pump. Whitch seems to work fine.   I can add an extra pump if i need more cfm...)
If my vac is to strong.. i can make a bleedvalve to reduce vacuum.   

But idialy i would love to have a perfect finish.

I use easy lease release agent..  denoulding is a breeze..




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Hanaldo
Hanaldo
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Well now you're starting to throw in other variables that make it hard to determine what is going wrong, but in this case I would suggest you have tried to do infusion with a resin that is not suitable for infusion. Flat sheet is quite forgiving to infuse, you dont have geometry trapping air as the resin flows around it. And contrary to what you might expect, thicker layups can actually infuse easier and better than thin layups, due to the flow channels created by the fibre crimp. Thin laminates have less space for the resin to flow, so actually require a lower viscosity resin.

When things aren't working, that is when you need to become scientific and repeat the experiment with as few variables as possible, changing things can throw you off finding the solution. I can understand running out of infusion resin, but waiting for more to arrive is probably a better idea than trying to infuse with hand laminating resin and binning all that carbon/glass/consumables/time. 

Release agent is not a concern here, parts are releasing so that is fine. Just a warning though, if you have waxed over the Easyleased moulds, you now need to treat that mould as a waxed mould, you can't put any more coats of Easylease on unless you strip it all off and start again. Wax on top of chemical release agent is ok, chemical release agent on top of wax is a disaster waiting to happen.

So, these last two experiments I would say are inconclusive because of the different resin used. I feel they failed because that resin didn't wet the reinforcement out properly, leading to an extremely lean resin content that explains both the poor surface finish as well as the poor interlaminar adhesion. The previous experiment failed due to bridging. And the one before that failed due to air leaks. Solve each of these issues all in the same layup without running into any other issues, and you will get a good result. Unfortunately this is the learning curve with infusion and composites in general, and at the moment the process is teaching. Its a shame school is expensive, but keep going with it and the process will deliver. 

With regards to your layup and choice of reinforcements, then I would say if it works for you then it works for you and there is no reason to change that unless you want to move to pre-pregs where your choice of reinforcement is more limited to what you can buy commercially. That said, virtually what you said about needing the flexibility of the glass and the stiffness of the carbon is the misunderstanding that most people have with composites. You don't get both properties, you actually can't make a fibreglass structure stronger or stiffer by adding carbon, just like you can't make a carbon structure more flexible by adding fibreglass.

Carbon fibre has an elongation to break of about 1.5%, while fibreglass has an elongation to break of about 5%. So when your laminate takes a load, it doesn't matter if you have 100 layers of carbon fibre with 1 layer of fibreglass or 100 layers of fibreglass with 1 layer of carbon or 50 layers of each, the entire laminate can still only stretch 1.5% before the carbon breaks. The fibreglass will keep wanting to stretch to 5% before it breaks, so if your laminate cops an impact or a point loading that stretches it beyond 101.5% of its total length, then all of the carbon in that laminate is going to break, while the fibreglass is going to keep going. Once the carbon is broken it isn't doing anything for the structure, so you only have the strength of the fibreglass. So to avoid your part flying to bits entirely, it would need the fibreglass to be strong enough to carry the required loads once the carbon has broken, which makes the carbon redundant; OR it would need the carbon to be strong enough that it can carry the required loads without stretching beyond 1.5%, which then makes the fibreglass redundant. A good analogy I heard for it is it's kind of like having a piece of aluminium (your carbon) and trying to reinforce it with a rubber band (your fibreglass). If you take that structure and bend it, the rubber band will bend significantly further than the aluminium but it isn't doing anything to prevent the aluminium from bending. 

There are situations where fibreglass is a superior material choice to carbon. If you have an application where you know a given laminate is going to be subject to loads that stretch it beyond 1.5%, then you have two options: make the laminate stronger by adding more layers so that it takes a higher load to achieve that elongation, which also means a heavier laminate. Or, use a material that can stretch further than 1.5% before it breaks, like fibreglass. 


Edited 4 Years Ago by Hanaldo
jeffrey bres
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Hanaldo - 4/17/2021 1:17:30 AM
Well now you're starting to throw in other variables that make it hard to determine what is going wrong, but in this case I would suggest you have tried to do infusion with a resin that is not suitable for infusion. Flat sheet is quite forgiving to infuse, you dont have geometry trapping air as the resin flows around it. And contrary to what you might expect, thicker layups can actually infuse easier and better than thin layups, due to the flow channels created by the fibre crimp. Thin laminates have less space for the resin to flow, so actually require a lower viscosity resin.

When things aren't working, that is when you need to become scientific and repeat the experiment with as few variables as possible, changing things can throw you off finding the solution. I can understand running out of infusion resin, but waiting for more to arrive is probably a better idea than trying to infuse with hand laminating resin and binning all that carbon/glass/consumables/time. 

Release agent is not a concern here, parts are releasing so that is fine. Just a warning though, if you have waxed over the Easyleased moulds, you now need to treat that mould as a waxed mould, you can't put any more coats of Easylease on unless you strip it all off and start again. Wax on top of chemical release agent is ok, chemical release agent on top of wax is a disaster waiting to happen.

So, these last two experiments I would say are inconclusive because of the different resin used. I feel they failed because that resin didn't wet the reinforcement out properly, leading to an extremely lean resin content that explains both the poor surface finish as well as the poor interlaminar adhesion. The previous experiment failed due to bridging. And the one before that failed due to air leaks. Solve each of these issues all in the same layup without running into any other issues, and you will get a good result. Unfortunately this is the learning curve with infusion and composites in general, and at the moment the process is teaching. Its a shame school is expensive, but keep going with it and the process will deliver. 

With regards to your layup and choice of reinforcements, then I would say if it works for you then it works for you and there is no reason to change that unless you want to move to pre-pregs where your choice of reinforcement is more limited to what you can buy commercially. That said, virtually what you said about needing the flexibility of the glass and the stiffness of the carbon is the misunderstanding that most people have with composites. You don't get both properties, you actually can't make a fibreglass structure stronger or stiffer by adding carbon, just like you can't make a carbon structure more flexible by adding fibreglass.

Carbon fibre has an elongation to break of about 1.5%, while fibreglass has an elongation to break of about 5%. So when your laminate takes a load, it doesn't matter if you have 100 layers of carbon fibre with 1 layer of fibreglass or 100 layers of fibreglass with 1 layer of carbon or 50 layers of each, the entire laminate can still only stretch 1.5% before the carbon breaks. The fibreglass will keep wanting to stretch to 5% before it breaks, so if your laminate cops an impact or a point loading that stretches it beyond 101.5% of its total length, then all of the carbon in that laminate is going to break, while the fibreglass is going to keep going. Once the carbon is broken it isn't doing anything for the structure, so you only have the strength of the fibreglass. So to avoid your part flying to bits entirely, it would need the fibreglass to be strong enough to carry the required loads once the carbon has broken, which makes the carbon redundant; OR it would need the carbon to be strong enough that it can carry the required loads without stretching beyond 1.5%, which then makes the fibreglass redundant. A good analogy I heard for it is it's kind of like having a piece of aluminium (your carbon) and trying to reinforce it with a rubber band (your fibreglass). If you take that structure and bend it, the rubber band will bend significantly further than the aluminium but it isn't doing anything to prevent the aluminium from bending. 

There are situations where fibreglass is a superior material choice to carbon. If you have an application where you know a given laminate is going to be subject to loads that stretch it beyond 1.5%, then you have two options: make the laminate stronger by adding more layers so that it takes a higher load to achieve that elongation, which also means a heavier laminate. Or, use a material that can stretch further than 1.5% before it breaks, like fibreglass. 


I will wait with infusion till i have more infusion resin. Thats what i planned.  

On the side of the laminate.    The prepreg is not an option for now.   3 to 4 layer is max what i can carry of 200gramms before it gets to heavy. Only glass id to flexible. And only carbon to fregile. The mix (i know you explained 3x)  is the best so far to make it light and still strong and stiff enough to not explode when s*** happens.

The cracked carbon isnt a problem
Then we just repair it. But only carbon is to expensive and carbon cevlar is another option.   
In my experiance with these boats. The carbon in the center is strongest. Most stiff and hanfles the most impact.

The carbon on the outside is 100% cosmetic.

But yes.   I will go back.  (I know easy over wax isnt gonna work. )
I did total of 12 coats easy. And only wax it after that. I use the easy as a backup failsafe.(i might be stupid)..

But still.  Ok.   Il start at 0 again.   Il take the infusion resin. Start with only glass(cheapedt)  and see what happens. (A transparrent boat is allso cool)

Il keep you updated.   All advise is welcome.

Allso on better layups.   But adding more layers isnt gonna be an option it will be to heavy.

Massimiliano
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Hanaldo - 4/17/2021 1:17:30 AM
A good analogy I heard for it is it's kind of like having a piece of aluminium (your carbon) and trying to reinforce it with a rubber band (your fibreglass). If you take that structure and bend it, the rubber band will bend significantly further than the aluminium but it isn't doing anything to prevent the aluminium from bending. 


It totally makes sense!
But then, what is the purpose of carbon/Kevlar fabric?

Lester Populaire
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Massimiliano - 5/18/2021 2:44:59 AM
Hanaldo - 4/17/2021 1:17:30 AM
A good analogy I heard for it is it's kind of like having a piece of aluminium (your carbon) and trying to reinforce it with a rubber band (your fibreglass). If you take that structure and bend it, the rubber band will bend significantly further than the aluminium but it isn't doing anything to prevent the aluminium from bending. 


It totally makes sense!
But then, what is the purpose of carbon/Kevlar fabric?

Mostly damage tolerance

GO

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