Carbon Over Glass Question, Lamination schedule questions.

Hi guys.
Here I got couple of question. I will make small RIB (6 meters), my customers asked me to use unidirection Carbon Cloth reinforcements. so here is the lamination schedule of Hull:

(outside- to inside)

Csm 300
csm 300
Carbon uni 300 0 deg
carbon uni 300 45
DB 800
DB 800
DB 800

CSM will be hand laid and rest will be infused one go with vinlyester resin. so it would be 7 primary layer. What about you guys with those schedule. is it works good, and what is the properties of carbon over DB layers? I need suggestion for lamination schedule from you guys. Thanks for advance.

 

Insane schedule.. no point nor reason for such.. Get a good book
BR Teddy

 

adam, where did you get these specs for the layup.....is it simply guess work or have they been sent to you...what do you expect from the carbon uni, and why the need. Is it just to say that the hull is carbon reinforced for marketing crap. or do you need the carbon for strength.....if so why.

 

TEDDY: so please give me some input

LandLubber: yes this is a guess works. usually i mirror the Carbon Uni between Corefoam. yes i need strength not for such marketing crap. what is your suggestion Please???

 

Ok.. Don't mix everything together. Those materials have totally different elongation before break. In your example the CF would carry 95% of the loading before breaking so all that glass around would have been mostly dead weight. So again.. get a book.. it's a bit more complicated to comprehend and you need it as reference anyway..

 

It never ceases to amaze me how folks will attempt seat of the paints engineering on high tech laminates.

Adam, designing plastic reinforced laminates requires a fairly good understanding of basic engineering principles. This is especially true of high modulus and/or elongation materials, of course this is assuming you want to take advantage, of the physical properties these fabrics bring to the table. There are many good texts on the various subjects involved. Maybe it would help if you described your project in much more detail and your experience level with structural engineering. If you're a novice, the best advice has been given, which is to absorb some knowledge on the subjects.

 

Teddy: Thanks so much man, In my 1 years in composite career, I JUST HEARD that it was an insane to combine. what a shame!! hahaha. but hey, once i notice that someone use 2 layer of unicarbon on long girder. thats why i think it also works fine on hull. need your suggestion in using carbon please, what is your opinion if i want to mixed up carbon with glass.

PAR: absolutely yes, my background isnt composite stuff, but engineering.also need your suggestion in using carbon please, what is your opinion if i want to mixed up carbon with glass.

 

TEDDY & PAR: is that means combining glass and carbon is totally useless, the glass is just only dead weight? so what is the alternative for 6 m hull? could you give me example of schedule, will appreciate it.

 

Adam,

Carbon fibre in a boat is nearly always used over a lightweight core material to provide separation between the skins, hence increasing the section modulus and stiffness. Sticking it in the middle of the laminate will add some small amount of strength, but its benefit will be inversely non-beneficial in proportion to the additional cost. As the others say these materials are not going to work well together.
Note that carbon needs epoxy resin and will be nowhere near its best with polyester. Depending on how much you use, it is possible to get cracking in the surounding laminates as the very stiff carbon won't give and the materials around it will deflect un-evenly which can create stress raisers.
Yes you could use it to stiffen a girder and it could work fine as you say (if it is engineered properly), but unless you value a very minor decrease in weight over a major increase in cost it is probably wasting money where you could use more compatible materials at a much lower cost.

 

Ok
get back to basics and remember them always
Carbon has little to no stretch at all !:?:
Kevlar is the oposite end and has a lot of stretch to the point of pulling out of a weaker resin
Glass is some where in between , it has stretch more than Carbon but less that kevlar !
There are differant glasses as well ,some are stronger than others!!

Now to go with that is resins !!
Polyester resin is the bottom of the heap and pointless using carbon with it .
Vinylester is in the middle with much better properties abd can use with carbon or glass or kevlar . Best and top of the heap is Epoxy !! But also remember all resins have there good and bad as well and are not all created equal !!


Mixing differant materials is a no no sort of , what you start with you should carry on with to get the best results in what ever you are making .
There are exceptions to that but !
A layer of Kevlar on the outside surface of a glass laminate can be used where there is a lot of abrasion because it is tough and more resistant to surface wear , you can and should also use a better resin to go with the Kevlar so vinylester or Epoxy should be used .

I will leave you to ponder the question you asked !!!. :?::?::?::?::?:

 

Adam, if engineering is your background, you should already know the answer to your issues. Research is the hall mark of all good engineering (how many times have I said this).

Telling use the length of your project and the very general type isn't remotely enough information for anything more then speculation about what you are trying to do.

You can combine these materials, but it should be done with an eye toward the physical advantages of each, which your laminate schedule currently doesn't. A dissertation on composite structure engineering isn't best reviewed on a discussion forum, you need to understand the characteristics of the materials involved, the options, choices typical approaches, etc.

In practically every composite boat I've seen (okay, every single one) the laminate schedule changes with global and localized loading, expected strains, etc. a single skin of a continuous thickness isn't the usual case. You need to access your loading and develop a laminate that will address each, with an appropriate margin to insure things don't fall apart when the loads are exceeded by happenstance or abuse.

In short and to directly answer your question, I'd use a higher elongation modulus fabrics, preferably with fiber orientation along expected load paths and of course with fabric choices, in a logical arrangement within the matrix and taking advantage of a resin system, that will offer similar elongation properties as the fabric choices.

 

Using Carbon on a boat of that type is absolutly crazy !,
Have made many R I B S over the years and twist , flex and racking are the things just about every manufacture does not take into consideration !
A laminate with two differant materials is a potentual disaster and uni will shead from end to end .

Like has been said already the lay up makes no sense ????.
2 x300 csm ?? what about 1 x 600 csm uses less resin !
2x carbon and one at 0 ???? the other at 45 Degrees ???? which way ???
3 x DB on the inside ??? .
Crazy man !! Not in favor of infusion either as makes the laminate like a carrot !!!!!.

Using uni glass on the outside of any boat is not a good idea . In the case of damage the layer would simply tear from end to end like a layer of paper in a book . Dangerous !!!
The figures my stack up on the computer screen but in practice its not good at all !!

 

ALL PEOPLE:
Thanks guys, you all are GURU this way. well i wont use those lamination schedule, it just nasty my guess work :-(

 

SO please give me alternatives either using carbon. tell me better lamination schedule, this is social project, your name may marked on the hull paints.

 

i saw review of Eric sponbeg on this thread
http://www.boatdesign.net/forums/materials/carbon-glass-relative-strengths-9664.html

According to his research (but was used sandwich and I will use solid) Does it makes sense if I uses these followong schematic?

outside to inside
csm 300x2 (or csm 600)
db800
db800
carbon uni maybe 90 (??????????)
carbon uni maybe 0 (?????????)
Db800
Db800

Needs your comments again.....na matter what u say. now im waiting while cover my face.