*


All times are UTC + 1 hour



Post new topic Reply to topic
 [ 10 posts ] 
Author Message
 Post subject: Cork for core ?
PostPosted: Thu Jun 18, 2009 12:00 pm 
Offline
Rare Poster

Joined: Wed Jun 17, 2009 2:29 pm
Posts: 9
Location: Athens, Greece
Hi,

I need to know your opinions and advices on using cork for core (perhaps two laminated sheets).

Thank you in advance!


{ SHARE_ON_FACEBOOK } { SHARE_ON_TWITTER } { SHARE_ON_ORKUT } { SHARE_ON_DIGG } { SHARE_ON_MYSPACE } { SHARE_ON_DELICIOUS }
Top
Profile
 Post subject: Re: Cork for core ?
PostPosted: Thu Jun 18, 2009 1:30 pm 
Offline
Frequent Poster
User avatar

Joined: Tue Feb 24, 2009 1:43 pm
Posts: 317
Location: Iv.G.-Slovenia
This is not so bad idea at all! :thumb:


Top
Profile
 Post subject: Re: Cork for core ?
PostPosted: Thu Jun 18, 2009 1:55 pm 
Offline
Very Frequent Poster

Joined: Wed Nov 20, 2002 1:00 am
Posts: 889
Location: rhode island
not sure exactly what you have in mind but ....opinion only.
i think the density will be a bit heavier than balsa (sg=.15-.2)
i also think cork is similar to bark veneer,
meaning pretty good compressive strength (150psi) and poor tensile and poor flexure strength

so a core filled with cork used only for its compressive and shear properties (all flexure strength provided by glass laminate) will be heavier than using eps or xps foam.

and comparable weight to a balsa end grain core.

but i dont think it can compete with balsa, cedar or pawlonia planks (long. grain) that will provide a lot of plexural strength.
and its not much stronger than cheap/light styrene core materials
( again, opinion clouded by total lack of any facts)


perhaps thin sandwich applications over a lighter core of something else.

but wood always looks good.

-regards,
bill


Top
Profile
 Post subject: Re: Cork for core ?
PostPosted: Thu Jun 18, 2009 1:59 pm 
Offline
Very Frequent Poster

Joined: Wed Nov 20, 2002 1:00 am
Posts: 889
Location: rhode island
someone posted this a long time ago.
the link is dead but i saved the attachment

material properties of various woods:
(download attachment)

also material properties for structural foam cores
http://boatdesign.net/articles/foam-cor ... /index.htm


Attachments:
wood.xls [55.5 KIB]
Downloaded 113 times
Top
Profile
 Post subject: Re: Cork for core ?
PostPosted: Thu Jun 18, 2009 2:33 pm 
Offline
Rare Poster

Joined: Wed Jun 17, 2009 2:29 pm
Posts: 9
Location: Athens, Greece
zfennell wrote:
someone posted this a long time ago.
the link is dead but i saved the attachment

material properties of various woods:
(download attachment)

also material properties for structural foam cores
http://boatdesign.net/articles/foam-cor ... /index.htm


Thank you!
This seems like excellent information. However, where could I read for the definitions of all these coefficients since my knowledge on materials mechanics is not so extended?


Top
Profile
 Post subject: Re: Cork for core ?
PostPosted: Thu Jun 18, 2009 8:50 pm 
Offline
Very Frequent Poster

Joined: Wed Nov 20, 2002 1:00 am
Posts: 889
Location: rhode island
the application of the terms may be more involved than you wish.
but here is a good place to start.
http://physics.uwstout.edu/Statstr/Stat ... Forces%20I

generic google search for:
-bending stress in simply supported beam
-design stress sandwich construction

if you're still interested keep asking questions.
in the meantime, copying existing layups will be extremely educational.

regards,
-bill


Top
Profile
 Post subject: Re: Cork for core ?
PostPosted: Sat Jun 20, 2009 4:52 am 
Offline
Very Frequent Poster
User avatar

Joined: Sun Jan 06, 2002 1:00 am
Posts: 2590
Location: Mauritius, waterman since 1960
Hi.
I,ve used cork on a board, but not for the core, I used it for pads and works great.
I believe you flex factor will also not be right and you will have to compensate with extra layers of glass or wahtever you intend using.
Nico


Top
Profile
 Post subject: Re: Cork for core ?
PostPosted: Sat Jun 20, 2009 4:59 am 
Offline
Very Frequent Poster

Joined: Thu Jun 05, 2003 3:37 am
Posts: 2362
cork for some parts of core, not all the core is cork, ok, a thin layer, maybe in some places....


Top
Profile
 Post subject: Re: Cork for core ?
PostPosted: Sat Jun 20, 2009 6:31 am 
Offline
Frequent Poster
User avatar

Joined: Sun Dec 15, 2002 1:00 am
Posts: 232
Location: Argentina
hi
found this great link explaining the role of the core
http://www.oneoceankayaks.com/Sandcore.htm
IMO the cork shear modulus is too low (see the pic "layers slide past each other" in the link)

besides cork seems to have a really low E ( elasticity modulus, is too flexible). the compression side might buckle under heavy load. But I'm just guessing, it'd be easier with actual numbers.

still, i'd give it a try on the "flextips" that many boards have nowadays.

pablo


Top
Profile
 Post subject: Re: Cork for core ?
PostPosted: Mon Jun 22, 2009 10:43 am 
Offline
Rare Poster

Joined: Wed Jun 17, 2009 2:29 pm
Posts: 9
Location: Athens, Greece
Thank you all for this valuable information! :D


Top
Profile
Display posts from previous:  Sort by  
Post new topic Reply to topic
 [ 10 posts ] 

All times are UTC + 1 hour


Who is online

Users browsing this forum: No registered users and 1 guest


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Search for:
Jump to:  
Powered by phpBB © 2000, 2002, 2005, 2007 phpBB Group