Honeycomb core for infusion?

Discussion in 'Fiberglass and Composite Boat Building' started by jim lee, Dec 9, 2011.

  1. jim lee
    Joined: Feb 2007
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    Location: Anacortes, WA

    jim lee Senior Member

    My prepreg friends are always laughing because they can use extremely light honeycomb core and, seeing we do infusion, we can't.

    With infusion we're limited by the crush strength of our solid foam cores. It seems that with honeycomb you get the crush strength without the weight because most of your core is air.

    Then the thought hit me, if someone made a composite core.. A honeycomb with the cells filled with an extremely light foam. The foam could be very light because the honeycomb would supply the crush strength. The foam only has to fill the space in between to keep out the extra resin.

    Anyone make something like this?

    -jim lee
     
  2. DGreenwood
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    DGreenwood Senior Member

    Yup it has been done...I don't know if it is still manufactured though?
     
  3. michael pierzga
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    michael pierzga Senior Member

    Sounds difficult to me. How would you bond to the honeycomb cells ? The foam filler would have no bond value
     
  4. tunnels

    tunnels Previous Member

    Your a bit slow out of the blocks old son been done for long time Check out NIDA CORE Is the first to spring to mind but i am sure there are others .:D
     
  5. DGreenwood
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    DGreenwood Senior Member

  6. tunnels

    tunnels Previous Member

  7. groper
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    groper Senior Member

  8. jim lee
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    jim lee Senior Member

    I don't think I want the resin to be the honeycomb..

    The idea was that if you had a good strong honeycomb, you could save the weight of the foam because it would then be just a filler. It didn't need to do anything. The nida core stuff uses the same weight foam filer as the core I use now so its no weight savings.

    -jim lee


    -jim lee
     
  9. Herman
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    Herman Senior Member

    Till so far I do not know of any succesful foam filled honeycombs. They do exist, but mainly for static purposes, such as dormer roofs (the foam prevents condensation in the honeycomb).

    If you want bragging rights, make your friends a panel with Core-cell, nicely infused, or just regular PVC foam, and a panel in honeycomb with the same skins. Give your friends a hammer, and tell them to destroy the panels.

    Honeycomb is not that good at impact, that is why they beef up the panel and use expensive material in the skin.

    At this moment stick to what you are doing: build high-quality, durable boats, and find a market for that.
     
  10. jim lee
    Joined: Feb 2007
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    jim lee Senior Member

    Well you know.. It was just a thought.

    -jim lee
     
  11. Herman
    Joined: Oct 2004
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    Herman Senior Member

    Go to bed, boy. It must be in the middle of the night in your place!
     
  12. idkfa
    Joined: Sep 2005
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    Location: Windward islands, Caribbean

    idkfa Senior Member

    Infusion honeycomb! anyone tried this stuff?

    Faced for Maximum Adhesion, Minimal Resin Use

    Utilizing a composite surfacing material, the open cell structure in Infusion Grade PP Honeycomb is sealed, thereby allowing the flow of resin during processing to remain at the bond line with minimal penetration into the honeycomb core. The veil provides a continuous substrate for 100% adhesion to the panel skin material. The core does not incorporate any flow paths, so a careful selection of glass reinforcements that have a resin flow path capability is required. To help facilitate a uniform flow of resin through the sandwich structure, additional pass through holes are added to the honeycomb that pierce the surfacing material at one cell and allow resin flow from top to bottom of the sandwich. Spacing of these holes is typically 4" on center.

    Infusion Grade PP Honeycomb features a composite surfacing material that is compatible with most laminating resins.

    Process Recommendations:

    Resin
    Infusion Grades
    Polyester, Vinylester, Epoxy
    Viscosity: < 200cps
    Gel Time: 45-60 minutes minimum

    Reinforcements:
    Infusion Grades
    Straight or Stiched Fabrics
    Continuous Strand or Flow Mat

    Pressure:
    Up to 1.0 bar both for Resin Injection and Flow

    Temperature:
    Process up to 150° F

    Flow Distance:
    24"-36" maximum with through core holes on 4" centers. Equidistance from Resin Inlets to Vacuum Outlets. Additional flow holes can be added as required.
     

    Attached Files:

  13. Steve W
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    Steve W Senior Member

    I havnt tried it yet but intend to in the near future, I don't really see any advantages over the other cores except of course cost which is very attractive. My interest is for flat panels for furniture, berth flats etc. I don't really see any weight savings over foam as any holes through the core are going to fill a whole cell which would be a lot heavier than a 2mm hole in foam.

    Steve.
     
  14. Herman
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    Herman Senior Member

    Re. weight savings: I have tried another variety (Nidacore) which was not particular light either. (at 5 lb/ft3 / 80 kg/m3). Resin uptake was higher than foam (at 1.2 kg / m2 against 1 kg/m2) but nothing extreme.

    With Nida, the largest disappointment was the shear modulus, which is fairly low, and the repairability. (once catastrophically hit a repair Always involves removing all core, and replacing. You cannot bond on the material itself.)

    For internals, you are OK. The price is good. If you want to save even more weight, go for a 60 kg/m3 / 3.5-4 lb/ft3 foam, or the extremists go for aramide honeycombs.
     

  15. petereng
    Joined: Jan 2008
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    Location: Gold Coast Australia

    petereng Senior Member

    Hi Jim Lee - By ultra light weight honeycomb what density do you mean? The lightest I know of thats usually used is 50kg/m3. Any honeycomd has to use a binding film to get the honeycomb to stick and this adds weight to the prepreg. So you need to get them to give you a sample of their lightweight sandwich with the full construction details so you can figure exactly what weight/m2 the panel is. Then you go and get 45kg foam and build the same laminates and I think you will find it to be the same weight as the honeycomb. If their 30Kg? 50kg? honeycomb is nomex the 45kg foam will not be as strong in the thru thickness direction in shear. But the shear strength required depends on the design parameters. So I think you can build an equal weight panel to the prepreg panel if you know some more of the details. Cheers Peter s
     
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