Interlaminar delamination


Interlaminar delamination
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Hanaldo
Hanaldo
Hanaldo
posted 10 Years Ago HOT
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Hi all, 

I have come across an interesting problem that I've never seen before, was hoping someone might be able to give me some insight. 

I made a false floor for a Ford F1000 using one layer of 200g carbon on the surface, and one layer of 850g biaxial fibreglass. The part was infused with epoxy, as I always do and have done hundreds of times before. 0 micron drop over 24 hours registered on my digital vac gauge prior to infusion, so absolutely leak free. Infusion went perfectly, everything wet out nicely etc. Left to cure for 48-50 hours prior to demoulding. This is when the issue became apparent. 

I removed all the consumables as I normally do, then used compressed air to blow the part off the mould. As I blew the air into the gap between the part and the mould, this happened:

https://fbcdn-photos-h-a.akamaihd.net/hphotos-ak-xfp1/v/t1.0-0/s600x600/21016_10152825175067541_9118438126811264876_n.jpg?efg=eyJpIjoidCJ9&oh=be567ad036387626e819bcdf03dc7eb1&oe=55F43FB6&__gda__=1445706436_bbbe1f0886d1310152416c0aa46241f5


First thought was "s***, must have left the clear packing tape in there!" (the supplier I get the fibreglass from annoyingly insists on placing clear packing tape on the cut line when the cut some off the roll). 

Anyway, kept going with removing the part from the mould (I use Frekote, so it's not like much effort was required, it virtually fell out), and it just kept happening:

https://fbcdn-photos-c-a.akamaihd.net/hphotos-ak-xat1/v/t1.0-0/s600x600/10641222_10152825174842541_7309903660955047004_n.jpg?efg=eyJpIjoidCJ9&oh=4638e32c13fdc5ff1e336f1b02923a91&oe=5630C982&__gda__=1445603971_d0cb5b56f9c47fd6feb2ec81b431d7d8


https://fbcdn-photos-e-a.akamaihd.net/hphotos-ak-xap1/v/t1.0-0/s600x600/11227882_10152825174997541_2261888080846947669_n.jpg?efg=eyJpIjoidCJ9&oh=317bafa64aeb25e29b7274bd7b9d85e4&oe=56214742&__gda__=1444882169_049de2aa67e6ef374a9345a1a27c4ca0




So I grabbed the offcut from the hole I cut in the centre, and the fibreglass peeled off the carbon easier than peel ply! 

https://fbcdn-photos-b-a.akamaihd.net/hphotos-ak-xpt1/v/t1.0-0/s600x600/11074002_10152825175637541_8322122438704484348_n.jpg?efg=eyJpIjoidCJ9&oh=354778260a3a301a700eaff5028436c7&oe=5626D43F&__gda__=1441731805_507f207247db647dc8ed356048bd6ff8


The 2 skins individually are very strong, the unidirectional fibreglass doesn't delaminate from the +45 degree layer when  placed under load:

https://fbcdn-photos-f-a.akamaihd.net/hphotos-ak-xfp1/v/t1.0-0/p320x320/10985481_10152825177987541_955878396418521519_n.jpg?efg=eyJpIjoidCJ9&oh=6812eed54ac22d07ae98a324f27a17e3&oe=56269F82&__gda__=1446210643_6f4cc88ad655faab387dc0096dd0eb4e


And the carbon is also strong, for 1 layer of carbon. So individually, the skins are performing very well and the resin is doing its job, it isn't delaminating from each skin. But there is just no interlaminar bond strength, I'm not exaggerating when I say it's harder to remove peel ply. 

These are materials and process that I have used many times, I'm not unfamiliar with any of it. But this is the first time I have seen this, and it's got me stumped. Anyone have any ideas? 
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Warren (Staff)
Warren (Staff)
Warren (Staff)
posted 10 Years Ago HOT
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It can be quite easy to delaminate a layer once it has initially seperated, which initially could have been caused by a number of things.  In essence, it's only the resin holding the layers together so a relatively fresh part would be easier to delaminate like that than something more fully cured. As you have mentioned it doesn't delaminate under load which is key.  It does seem a little strange that it delaminates easier than peel ply.

Warren Penalver
Easy Composites / Carbon Mods - Technical Support Assistant
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Interlaminar delamination
Hanaldo - 10 Years Ago
     is there a binder on the fibreglass material? i cant think why it would have such little bond...
scottracing - 10 Years Ago
     It's a stitched biaxial, so there's no binder. In any case, I have used this same fibreglass...
Hanaldo - 10 Years Ago
     It can be quite easy to delaminate a layer once it has initially seperated, which initially could...
Warren (Staff) - 10 Years Ago
     Individually the plies of fibreglass uni don't delaminate, but the carbon and the fibreglass do...
Hanaldo - 10 Years Ago
             It's hard to say for sure because the biaxial glass (and possibly the carbon?) are not supplied by...
Matt (Staff) - 10 Years Ago
     Thanks for the reply Matt. Indeed none of these materials are supplied by you, these are all local...
Hanaldo - 10 Years Ago
     Just to update this; I investigated this issue further with the supplier after I did various tests...
Hanaldo - 10 Years Ago
     good to hear you found the problem with the material!
scottracing - 10 Years Ago
             nice to read your investigation, We had some same problems while building a boat, we first thought...
matthieutje65 - 10 Years Ago
     Also, be very carefull with "unknown" peel-ply ... I was given a few sq- metres of peel-ply, it...
Dravis - 10 Years Ago

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