Is wood stronger than metal per weight?

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No big deal, but I want to know. Partly curious.
I want to use a crosswise board or an aluminum rectangular tube (or whatever other metal would be appropriate) as a two wheel platform, for the rear end of a tricycle.
I want more intelligent/experienced guesses about the situation. Not concerned about workability, weather resistance, etc.
I see some opinions on the Internet that go both ways.
Thanks.
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Look for discussions on homebuilt wooden airplanes.
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What's your definition of "stronger"? Compression or tension or shear? Resistance to flex (i.e. stiffness) or ability to take multiple cycles of flex (fatigue resistance)?
I'm going to guess for your tricycle application that stiffness is a key parameter, in which case a tube is probably the stronger structure.
John
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On Wednesday, July 27, 2016 at 3:16:49 PM UTC-4, John McCoy wrote:

If the user will be riding the tricycle like we did when I was young, "multiple cycles of flex (fatigue resistance)" is also very important.
If it wasn't the driver riding with one foot on the rear platform, pushing with the other, it was a friend/sibling standing on the platform.
http://media.gettyimages.com/photos/two-children-riding-one-tricycle-picture-id530860074
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Is your bike made of metallic tubing or wood?
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wrote:

Properly used, wood is capable of excellent performance, for example the Mosquito airplane, longbows, stagecoaches, skis, wood-framed birchbark canoes and Egyptian chariots, which are remarkably light for a fast off-road vehicle. http://www.touregypt.net/featurestories/chariots.htm
Improperly used it's dangerous because the properties of individual pieces are unpredictable and strong joints require experience to design and skill to make.
Wood, steel and aluminum have all been used to build light and strong airplanes, even jet fighters. It's up to you to learn how to apply them.
--jsw
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On 7/27/2016 2:50 PM, Cydrome Leader wrote:

Well, this is true, ipe is stronger than aluminum foil but Balsa is weaker than titanium.
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wrote:

This is a manageable question if you specify acceptable dimensions and how the axle is loaded (it depends on the structural section and dimensions -- either one can be stonger per pound -- except that it also depends on whether the load is applied in a point), but wood is so complicated, from a structural standpoint, that just asking "which is stronger" just leads around in circles.
Here's an example: Douglas Fir is three times stronger than aluminum per pound in compression -- parallel to the grain axis. Perpendicular to the grain axis, fir is 1/3 as strong as aluminum in compression. Tension is much more complicated because of the difficulty of attaching a load to wood in tension.
If you want to get serious about comparing the two, the easy way is to look up construction tables for bending horizontal wood beams, and then getting the specs on an aluminum section that you choose. That is, one you can *get*.
They're both on the same order or close to it. But arranging the design for applying loads will give aluminum the advantage. That's one of the problems with engineering with wood, unless your loads are purely in compression.
If you want to get into it, this will occupy you for a while:
http://www.fpl.fs.fed.us/documnts/fplgtr/fplgtr113/ch04.pdf
This one has good stuff on beams:
http://www.gutenberg.org/files/12299/12299-h/12299-h.htm
The Forest Products Laboratory has a wealth of information, if you have nothing else to do with your life.
BTW, aside from aircraft, a very successful race car from around 1960 had a chassis made of plywood (the original Marcos GT). And the stiffness and strength of fir plywood is roughly equivalent to a cored composite made from polyurethane foam, ordinary S-fiberglass, and polyester resin.
Not bad.
--
Ed Huntress

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Here's how to determine the modulus of elasticity value for the tables: http://www.doitpoms.ac.uk/tlplib/wood/wood_stiffness.php
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On 07/28/2016 8:56 AM, Ed Huntress wrote: ...

There's also the torsion box...
--




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....and the Spruce Goose and de Havilland Mosquito bomber and some WWII landing craft. ;)
nb
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Technically that is a grass.
John
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On Fri, 29 Jul 2016 01:38:19 -0000 (UTC), John McCoy

Many decades ago, when Japanese cars were still a joke, Road & Track ran a spoof about a Japanese F1 car, with a frame made of bamboominum tubing...
--
Ed Huntress

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On 07/28/2016 8:38 PM, John McCoy wrote:

Technically, that would be botanically...
--


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Gunner, we usually only call dicots 'wood'. 'Woody' monocots are not usually included in that genre. A weird exception might be palm trunks used as fence posts, but they're _barely_ 'woody', at their best.
Lloyd
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"Lloyd E. Sponenburgh" <lloydspinsidemindspring.com> wrote in

I would not call bamboo products wood. I suspose I might refer to a quantity of bamboo intended for building something "lumber".

I just cut a dead palm down. I would not call that wood either. ("pain in the ass" is what I would call it...)
John
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On Sat, 30 Jul 2016 01:15:40 -0000 (UTC), John McCoy

Do you call particle board "lumber"? I suppose bamboo is closer to butcher block but I wouldn't call it "lumber", I don't think. The point being that it's made up of a bunch of small pieces (strips) glued together to make something of a useful size.

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Indeed, it is!
L
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typed in rec.crafts.metalworking the following:

    I think the technical term is "Woody." -- pyotr filipivich "With Age comes Wisdom. Although more often, Age travels alone."
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wrote:

Which is grass. ;-)
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