Hi All,
A slightly technical question about wetting out fabrics.
What is actually happening? What are we trying to achieve?
For glass fibres am i right in thinking the fibres are hollow, so we want the resin inside the fibre, Or are we aiming to just encapsulate it?
Same with carbon
Any replies are greatly appreciated
Get some book on composites for the beginners
Thanks, I have quite a bit of experience, but this is one of the questions I’ve never quite understood.
I understand we are trying to replace the air with resin, but its where is the air, around the fibres or inside them too?
This is specifically in regards to hand layup, my background is more in prepreg and infusion
fibres not hollow, you are onlly covering them from the outside, how could you think they where hollow and still be able to put resin inside those thin hollow fibers by hand laminating ?? amazing …
We’re glueing the fibres toghether with resin 
There are hollow glass fibers, but you do not come across them often.
So basicly what you are doing is filling the air between the fibers with resin.
What rallyfan is trying to understand is the reason why when you glue these fibres together makes them a different material from the 2 originals and what is exactly happening in micro…
So rallyfan what is happening is this : the carbon fibers have very very high enlongation stress resistance… so when the resign goes around them in micro there is rigid material around every path of every fiber which when you try to deform in almost any direction some part of the fibers tend to get enlengthened…and they resist to that …so there you have the strength of the cured part …strength comes with the resistance of the fibers to get longer. So when you have a plate for example and you try to push it downwards… the fibers at the bottom resist to elongation… and the resin is what keeps the fibers together and transfers the forces from any direcrion alongside the fibers. It also doesnt allow them to move and make them resist to any force of enlongation.
And something about you jigger what the @@## is this attitude with the " amazing " world? You always have inteligent questions? If you thing some question is very stupid then dont reply or dont waste your time with it… but you dont have to act like this…
^^^^^^^ Agreed
In jiggers defense, Rallyfan DID say he has experience. But to think that glass and carbon fibers are hollow is a little strange. To have experience in infusion and prepreg, but not understand the basic basics of composites, is shocking. It’s like having someone fix your car, but they have no idea how the pistons move.
To answer the question, Creator more or less nailed it. Fibers are fibers, not tubes. The resin grips the fibers and the resin holds it all in place, and transfers loads. There is no difference between wet layup, infusion, or prepregs in this point. The goal is the same. Replace air with hard resin. From that, things get a whole hella more complicated (sizing, voids, microcracking, shear strengths, tension/compresion, etc.
Thanks for the replies guys - especially Creator, just the answer I was looking for!
There was a bit more to the question than what was initially written, but a couple of the responses on here seem uncalled for - so what if someone if asking a question that seems very simple? There is usually very good reason for someone to ask a question in the first place - otherwise it wouldn’t have been asked