KIS-List Digest Archive

Fri 08/14/15


Total Messages Posted: 3



Today's Message Index:
----------------------
 
     1. 07:02 AM - Re: Fiberglass vs Carbon Fiber for my layup (M Ketteing)
     2. 06:47 PM - Re: Lay up (Galin Hernandez)
     3. 07:04 PM - I have been missing so much information (Galin Hernandez)
 
 
 


Message 1


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    Time: 07:02:18 AM PST US
    From: M Ketteing <aeromomentum@yahoo.com>
    Subject: Re: Fiberglass vs Carbon Fiber for my layup
    Hi Galin, I will be up there soon. Really. I just have a lot of catching up to do. The choice between carbon and glass is not that simple. Yes, carbon is about 2.5 times as strong and as stiff as glass. But they way they are used actually can have a larger impact on strength and stiffness. For example in bending a solid layup of 10 plies of glass is stronger and stiffer than a solid layup of 5 plies carbon since the glass is twice as thick. Keep in mind that when you double the thickness you about quadruple the bending strength and the stiffness increases about 8 times. So to replace the 20 total plies of glass you would need a total of about 13 plies of carbon to get the same bending strength. But to get the same bending stiffness you would need about 15 plies of carbon. Since your repair is more of a local stiffness issue you really need to meet (or beat) the original stiffness. That being said, since the outer plies are doing more work a glass and carbon sandwich can work very well. But this will require a semi balanced layup with carbon on both sides. Or the original layup in glass with the addition of carbon more as an integrated backing plate. There are many ways to do this that will work. But if it was me I would also want to make it so it will never happen again. I like 8 plies glass and 3 plies carbon from the outside (bottom) and 10 plies glass and 5 plies carbon from the inside. It can also be done all carbon and this would save about 5 plies total so would maybe be a little neater. Mark Kettering -------------------------------------------- On Thu, 8/13/15, Galin Hernandez <galinhdz@gmail.com> wrote: Subject: Re: KIS-List: Fiberglass vs Carbon Fiber for my layup To: "kis-list@matronics.com" <kis-list@matronics.com> Date: Thursday, August 13, 2015, 8:18 PM THANKS but I was wondering more along the lines of Carbon vs Glass, not the actual number of plies. Assuming the strength will be the same (no beefing up) what are the pros and cons ofmore plies of glass versus less plies of carbon or does it really matter? On Thu, Aug 13, 2015 at 7:16 PM, Alfred Rosa <fredorosa@gmail.com> wrote: I think 10 glass or 5 Carbon plies is pretty much a wash. If you really want to beef it up use 10 plies of Carbon. Sent from my iPhone On Aug 13, 2015, at 6:12 PM, Galin Hernandez <galinhdz@gmail.com> wrote: As I get ready to do the layups for the landing gear I was wondering about using Carbon Fiber instead of Fiberglass.Let's say instead of 10 plies of glass, use 5 plies of carbon. What would be the pros and cons of this idea? Good idea or bad idea? What sayeth the list? 3D============================================ 3D============================================ 3D============================================ 3D============================================


    Message 2


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    Time: 06:47:22 PM PST US
    From: Galin Hernandez <galinhdz@gmail.com>
    Subject: Re: Lay up
    THANKS to Charlie for forwarding this post since I did not get it. I was just curious and wondering as to which is the best way to skin this cat. :) On Fri, Aug 14, 2015 at 9:34 PM, Charlie Smith <smith.smithcts@gmail.com> wrote: > It was his post on the forum. > > > PostPosted: Fri Aug 14, 2015 6:02 am Post subject: Fiberglass vs Carbo n > Fiber for my layup Reply with quote > > Hi Galin, > > > I will be up there soon. Really. I just have a lot of catching up to do. > > > The choice between carbon and glass is not that simple. Yes, carbon is > about 2.5 times as strong and as stiff as glass. But they way they are us ed > actually can have a larger impact on strength and stiffness. For example in > bending a solid layup of 10 plies of glass is stronger and stiffer than a > solid layup of 5 plies carbon since the glass is twice as thick. Keep in > mind that when you double the thickness you about quadruple the bending > strength and the stiffness increases about 8 times. > > > So to replace the 20 total plies of glass you would need a total of about > 13 plies of carbon to get the same bending strength. But to get the same > bending stiffness you would need about 15 plies of carbon. > > > Since your repair is more of a local stiffness issue you really need to > meet (or beat) the original stiffness. > > > That being said, since the outer plies are doing more work a glass and > carbon sandwich can work very well. But this will require a semi balanced > layup with carbon on both sides. Or the original layup in glass with the > addition of carbon more as an integrated backing plate. > > > There are many ways to do this that will work. But if it was me I would > also want to make it so it will never happen again. I like 8 plies glass > and 3 plies carbon from the outside (bottom) and 10 plies glass and 5 pli es > carbon from the inside. It can also be done all carbon and this would sav e > about 5 plies total so would maybe be a little neater. > > > Mark Kettering > > > Sent from Mail <http://go.microsoft.com/fwlink/?LinkId=550986> for > Windows 10 > > > *From: *Galin Hernandez > *Sent: *Friday, August 14, 2015 7:23 PM > *To: *Charlie Smith > *Subject: *Re: Lay up > > > For some reason I did not get Mark's e-mail. Can somebody re-send it. :( > > > On Fri, Aug 14, 2015 at 7:07 PM, Charlie Smith <smith.smithcts@gmail.com> > wrote: > > Galin, > > > Mark=99s advice seems on target to me. I=99d take it if he w ere offering it > to me. Just remember that the failure wasn=99t caused by a lack of strength > of the composite. The metal washer was over stressed so it rightly was a > failure of the metal components and the rubber barrier. The rest happene d > due to fretting and that will happen if metal rubs against composite > materials (carbon or glass) regardless of thickness. The thickness will > only change the time it takes to wear through. > > > Charlie > > > Sent from Mail <http://go.microsoft.com/fwlink/?LinkId=550986> for > Windows 10 > >


    Message 3


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    Time: 07:04:58 PM PST US
    From: Galin Hernandez <galinhdz@gmail.com>
    Subject: I have been missing so much information
    I just realized (dumb me) that there is a KIS forum at Matronics and not just the e-Mail system. I am just now reading many of your posts that I didn't even know existed. So if I haven't responded to any of your posts, it is because I never saw it. I will spend the next few days looking at the forum and trying to catch up. There is so much information there.




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