Fiberglass layer strength

Discussion in 'Materials' started by rturbett, Jul 6, 2021.

  1. rturbett
    Joined: Aug 2005
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    Location: FINGER LAKES, NY

    rturbett Senior Member

    we are building decks using divinycell- my friend had done good work putting two layers of 7 oz cloth on each side of the diviny.

    Is there any advantage to doing multiple layers of glass instead of just a single layer? For simple math, would a single 10 0z layer on each side be as strong as two 5 oz layers?

    FYI we are not vacuum bagging, but still getting good adhesion

    Thanks for any thoughts or expeience.

    Rob
     
  2. fallguy
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    fallguy Senior Member

    Turning the same glass in different directions is stronger, ceteris parabis than the same total weight cloth not turned.

    Since the 7 oz is likely a woven, turning the follow on layer when possible, is stronger. For turning, you have to determine how many layers total and turn accordingly.
     
  3. Mr Efficiency
    Joined: Oct 2010
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    Mr Efficiency Senior Member

    You will need a little bit more glass on the outward facing side, to get a measure of puncture resistance if something heavy (and sharp edged) is dropped. 2mm minimum I would say
     
  4. ondarvr
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    ondarvr Senior Member

    What type of resin?
     
  5. rturbett
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    rturbett Senior Member

    Thanks- two layers it is- for the point that fallguy made. Using epoxy resin
    Rob
     
  6. fallguy
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    fallguy Senior Member

    Just remember it needs to make sense visavie overlaps and such; it may not be worth turning 45 versus 10 degrees or going with a single layer if you are forced to overlap and butting glass is really not wise.

    For my cockpit panels, I used triax and turned the stuff 90 degrees to get some 0 strands on the width and pretty sure it was wise. For my transom, turned each of four layers of biax about 20 degrees...etc. had to accept using overlaps on cockpit either way

    plan ahead and you can also relief for overlaps and reduce fairing
     
  7. rturbett
    Joined: Aug 2005
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    rturbett Senior Member

    Agree- butting glass would be pointless to the mission here. the construct is able to handle overlaps where needed
     

  8. fallguy
    Joined: Dec 2016
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    fallguy Senior Member

    Another thing to consider, the top side of a deck is not the side in tension and the bottom side does more work and may be invisible, so you can take advantage of that at times by making the bottom much stronger. A walkable deck with onlg a single layer of less than 10 oz is a bit light...
     
    bajansailor likes this.
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