Is this wood candidate as a core ?

[trimix]

Is this wood candidate as a core ?

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A japanese friend give me these values concerning a wood named "Girinogi".

Density
- Oven dried 0,23 (g/cm.3)
- Air dried 0,29 (g/cm.3)
Shrinkage coefficient
- Radial 0,092 (%)
- Tangential 0,184 (%)
- Volume 0,294 (%)
Compression strength parallel to grain 20,74 (MPa)
Bending strength 38,59 (MPa)
Bending modulus of elasticity 4805 (MPa)
Shear strength parallel to grain
- Radial section 4,8 (MPa)
- Tangential section 4,95 (MPa)
Compression strength perpendicular to grain
- Partial compression at proportional limit Radial 2,84 (MPa)
- Partial compression at proportional limit Tangential 2,45 (MPa)
- Compression at proportional limit Radial 1,76 (MPa)
- Compression at proportional limit Tangential 1,61 (MPa)
Tensile strength parallel to grain 46,48 (MPa)


Is this wood will be a good core for a sheated stripplanking building from a mechanical point of view ? (all the other aspect such as humidity, gluing and so one are good)

How can I compare it to a WRC scantling ?

Trim

[gonzo]

It is stronger than foam, so if it is just a core it should do fine. How about gluing characteristics?

[yokebutt]

Seems about on the order of twice the density of typical balsa-core, and since I'm too lazy to look it up myself, do the other properties follow suit?

Yokebutt.

[John ilett]

Another option I have mentioned before on this forum is Paulownia. Density is 280kg compared to western red cedar 350kg and it's half the price too.
I imagine that some of the timber data you have mentioned may not be so relevent when it is sheathed with glass. Skins take much of the loads.

[trimix]

Originally Posted by John ilett

Another option I have mentioned before on this forum is Paulownia. Density is 280kg compared to wester red cedar 350kg and it's half the price too.
I imagine that some of the timber data you have mentioned may not be so relevent when it is sheathed with glass. Skins take much of the loads.

Dear John,

Could you please give us some elements of comparisons ?
It could be interresting for all would be for example :
1) to take an average scantling of a 40' sailer made in WRC stripplanking
2) compare it to the equivalent scantling for a glass/epoxy with a balsa core hull
3) compare it to the equivalent scantling for a sheated stripplanked Paulownia hull
4) compare it to the equivalent scantling for a real stripplanked Paulownia hull
5) do 3) and 4) with values I give in the beginning of this thread
6) and then compare the density of all the scantlings to know if Paulownia is
interresting to save weight !

I have now mean to do it but I would be very happy if someone can do it !

[John ilett]

Numbers are not my thing. A rough estimate to calculate the weight saving is simply the core weight difference of 70kg between WRC and paulownia. I think an identical laminate would be ok in this case. So work out your timber core volume and your done!

[yokebutt]

John,
That just way too simplistic, I think you need to sprinkle your missives with some complicated equations to make them more believable.

Regards,
Yokebuttocks.

[yokebutt]

Paulowhat? Can't even pronounciate that, must be some strange and exotic down-under material.


Yokebutt.

[John ilett]

I think it could be that simple, 280kg Paulownia is a reasonable saving but not such a significant difference as WRC 350kg is to foam at 80kg. So the required laminate must be very close ,if not the same.

here is link re growing paulownia in the US http://www.paulowniatrees.org/

http://www.paulowniasupply.com/paulownia_uses.htm

It's grown in Australia too.

It even looks good

[nero]

Do not waste your time with Paulownia. ... That is here in the US. I researched the wood and talked with the president of the paulownia association and one grower. The wood is good, but it is too soon here to get any quantity of it. Maybe in 5 to 10 years. Also, it is not an inexpensive wood here. Nor can an individual import wood into the states. (gov restrictions ... land of the free?) Nor with time will the wood become cheaper here. The producers are coordinating harvesting so as not to dump a bunch of wood on the market. (I think this falls under price fixing illegalities)

Also, from stumbling around the wood as a core question. Wood is a structural core. Bow to stern it can provide 100 % of the structural resistance to forces. Sheathed in glass, the glass provides the strength in the direction that wood is weak. So even a stronger, heavier wood, will need to stay about the same thickness to keep the glass skins far enough apart.

Wood uses less fiberglass in the skins than do foam cores.

regards