Question On Carbon Kevlar

Discussion in 'Fiberglass and Composite Boat Building' started by HAMMERHEADHM, Sep 24, 2012.

  1. HAMMERHEADHM
    Joined: Sep 2012
    Posts: 2
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    Location: GAINESVILLE, FLORIDA

    HAMMERHEADHM New Member

    We Race Airboats In Florida. A Builder Here Has Built Many Carbon Kevlar Boats. I Have Had At Least Seven People Call Me And Tell Me Thier Carbon Kevlar Boats Are Delaminating. I Thought The Guy That Was Bulding These Boats Was Wet Bagging Them But It Turns Out That They Are Handlaying Them And Using A Sqeegee For Removing Excess Resin. What They Are Telling Me Is He Lets Each Layer Harden Sands And Applies The Next Layer. He Is Using A Scrimmed And Scored Core And Epoxy Resin. I Have Recently Got My Shop Set Up To Do Inusion And Have Only Done Fiberglass To This Point. My Question Is, Is It Likely For Me To Encounter The Same Problem Of Delamination Using This Method And Is It Standard To Put Layers Of This Material Back To Back With No Surface Veil Between The Layers? Weight And Rigidness Are Of The Utmost Importance With These Raceboats, But Suggestions Of Other Materials And Methods Are Welcome. I Am Spraying Gel And Skinning The Outer Layer With 3/4 Oz Mat And Then Infusing The Entire Laminate With Stringers In Place, Then Hand Laying The Infused Deck Last. I'm Considering Laying The Carbon/kevar Boat Without Gelcoat And Painting Afterwards To Save The Weight Of Gel And Skin Layer. I'm Wondering If This Will Mess Up The Finish In My Mold? Thank You In Advance For Any Answers And Imput! Im Relativley New At This So Be Easy On Me!
     
  2. coolgps
    Joined: Jun 2012
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    Location: Xiamen

    coolgps Junior Member

    The delamination is caused either by compact or the resin compatibility. I am working on 60ft carbon fiber boat. When the resin is not very compatible with fiber, you handlaminate with it, you can easily peel every layer off by your hand.
    You can make one 2mm thick panel, cut it into strips, find a lab to test its tensile strength.The key point is not the strength, it is the way it breaks. When the strip breaks in fracture, it means the resin is compatible with fiber, if it breaks in delamination, it means not.
    About you don't want to spray gelcoat or paint first, in big boats, I never spray any gelcoat or paint first, just pay attention to your release wax, so be easy on this.

    Forgot to say, glass fiber compatibility with resin is good, no need to worry your glass fiber infusion.
     
  3. tunnels

    tunnels Previous Member

    Carbon and Kevlar are opposits !!. carbon has no stretch and kevlar has miles of stretch, to the point of tearing out of the resin if its not strong enough ,so why use two completely differant materials together ???? if theres delamination the resin is the problem ,must use a better resin ,saying epoxy means almost nothing .Theres a million epoxys all differant ,all have there own specific uses !!.
    Sounds like you need a tough epoxy !!!
     
  4. coolgps
    Joined: Jun 2012
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    Location: Xiamen

    coolgps Junior Member

    Oh boy, you need to add comma to your words, it is very difficult to read your post every time~~~:p:p
     
  5. coolgps
    Joined: Jun 2012
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    Location: Xiamen

    coolgps Junior Member

    There was one rib i infused before, the lamination have carbon fiber and kevlar in it. I also don't understand why they mixed these two together. Maybe add one layer of kevlar will make a Kevlar.
     
  6. tunnels

    tunnels Previous Member

    There is a purpose to mixing but im damned if i can see the reasoning behind it .
    I remember seeing a boom on a americas cup boat the was carbon and kevlar and it snapped the carbon ,but the kevlar held on and didnt break ,so in that respect as a safety measure it would have its uses ,but if the layer of kevlar had been carbon it might not have broken in the first place .For performance oriantated things shape is very important . Simply by changing shape can increase strength without adding more material and weight .
    To understand shape equals strength go have a look at a modern day car, its a perfect example . Cars have become lighter over the years but are stronger to go with it . The steel used has improved yes but they use a lot more shapes ! The shapes are more aerodynamicly designed to allow smoother air flow over the body and you dont get wind noise like used to get in the older boxey shapes of the past .
     
  7. tunnels

    tunnels Previous Member

    He Lets Each Layer Harden Sands And Applies The Next Layer
    This alone is bad practice with any kind of laminating !!! wet on wet always !!! microscopicly theres a layer of just resin between the layers of materials . and its the problem ! You could use a vey light chopped strand matt 125 gram or have seen carbon tissue at the last composite show i went to in Shanghai a month back .
    With any sort of movement the resin is failing and breaking and delamination !
    If you do wet on wet lay ups and peel ply and roll it and dont use squeegees the peel ply will leave the right amount of resin the material needs . In 35 years i have never found a use for sqeegees ,they are more trouble than what they worth .
    Reguardless what every one thinks some where there is a fine line of how much resin you can suck out of a laminate and how much you should leave in there .
    With resin infusion you could get breakages because of the lack of resin !! Like i said you need a "tough" resin!! it needs to be able to stand punishment ,much differant to what a boat hull ever gets .
    And if you guys are racing there should be a weight restriction placed on the boats ! that will put paid to dangerous practices of extra light and unsafe breakable boats . :mad:
     
  8. HAMMERHEADHM
    Joined: Sep 2012
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    Location: GAINESVILLE, FLORIDA

    HAMMERHEADHM New Member

    I'm sorry coolgps I dont understand either of your posts! tunnels thanks for your reply!
     
  9. tunnels

    tunnels Previous Member

    What he is saying is theres a issue with the resin as well . if its doing its job prperly you should never be able to peel the laminates apart without tearing each one . so find a better resin !! like i said Tough is the key West do a rubber toughened resin that i have used ina glue and it will not come apart what ever you stick with it !!! There a list of resin companies as ong as you arm they all have differant products so do some searching !!,Tough is the key
     
  10. tazmann
    Joined: Aug 2005
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    Location: California

    tazmann Senior Member

    I had the brain storm to put Kevlar on my boat but after talking with a friend of mine that builds and fly's RC planes, He told me it pretty tough to get it wet out 100%, he vacuum bags using west systems epoxy and said he crashed a few that got torn up pretty bad and you could tell the Kevlar had a lot of dry areas even though it look like a good wet out.
    My guess with the delamination problem would be like tunnels said the resin or the guy is laying the fabric up dry then wetting it out not getting the resin under the fabric 100%
    I have tried the squeegee a couple times now and I seem to make a bigger mess out of it, I do better with a 1/4" nap paint roller of the cheap variety and just chuck them in the trash after about 30 minutes use
     

  11. tunnels

    tunnels Previous Member

    If you are laying a material that you cant see the resin in wet the underside and turn it over and place it onto a really wet surface as well then roll with a hard roller and bring the resin up throught the material from underneath !!Also use peel ply over the top!!, it will tell you visually whats wet and whats not .
    Always use slow hardening resin as well ,not fast!! . All Resins have a wetting agent added to make the resin cling and spread long the fibres all by its self !BUT it needs time to work properly .
    Wetting under and bringing the resin up is the best and easyest way and with the peel pyl that helps even more .
    The Peel ply should look wet and shiney on the surface if its not there not enough resin in the material under it . I can never push the merits of peel ply enough . if the layer has to mush resin it comes up on top pf the peel ply and when it gone hard will get ripped off with the peel ply . If the material is to dry the peel ply wont wet and will not have a shine !!! no shine need more resin !!its simple to use , and after you get used to the nice finish it leaves after you rip it off you wonder why you never use it long ago .
    The resin to fibre is almost at it optimum percentage !!
    You can get close to resin infusion percentages when you doing multipal layers wet on wet and finshed with peel ply and rolled out nicely with a hard roller .

    And as for the use of Kevlar ,remember layer of thick Kevlar is very abbrasive resistant and tough those are the only qualities it has !!so is that really what you wanting :confused: ??
     
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