How strong is a carbon fiber guitar, really?

[SteelPastor]

Originally Posted by Doubleneck

If you look in just carbon fiber literature they say alternating multiple weave patterns is important for maximum strength. The reality is you do not need maximum strength in a guitar setting. I think the unidirectional top has tp be weaker, but it is that property that gives it a different sound. Certainly it is still stronger than wood.

I thought the unidirectional top was only the top layer and did not affect the overall strength of the top? e.g. that it has several layers going in different directions under the top/visible layer?

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[Doubleneck]

Originally Posted by SteelPastor

I thought the unidirectional top was only the top layer and did not affect the overall strength of the top? e.g. that it has several layers going in different directions under the top/visible layer?

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To me if that were the case it would be the same as the Black Ice model, there it is only the top layer that is different, and here they say the sound is the same as their weave guitars. I do believe it is unidirectional the whole way or more than just the surface.

[Doubleneck]

Word from those who know mostly unidirectional layers but also some running other way for strength.

[alpual]

Wow, thanks for all the info!

I guess the consensus is that it's pretty strong stuff. Figured. I bet I could break it if I tried, but I'm not actually trying to break it. Much as I might flatter myself, my palm isn't a hammer.

I have seen Rodrigo y Gabriela a few times. They rock. She has Yamaha developing guitars to her technique, with seven piezo pickups scattered throughout the body to pick up the percussion. Also: she says "they’ll send one guitar after another, just because they keep developing new things."
Unfortunately, I don't have that option... and I play with a pick, steel strings instead of nylon, and I tune it down a whole step on a jumbo with heavy strings (69 on the bass).

I do love my guitars, and I don't play my baritone with a pick for exactly this reason, but I don't want to abandon that style of playing, so I'm looking for a solution that doesn't mean custom instruments shipped to me free of charge on a regular basis. Unless somebody has that hookup?

[alpual]

Originally Posted by Doubleneck

1- Carbon Fiber has High Strength to Weight Ratio (also known as specific strength)

Strength of a material is the force per unit area at failure, divided by its density. Any material that is strong AND light has a favourable Strength/weight ratio. Materials such as Aluminium, titanium, magnesium, Carbon and glass fiber, high strength steel alloys all have good strength to weight ratios. It is not surprising that Balsa wood comes in with a high strength to weight ratio.

The following figures are offered for comparison only and will vary depending on composition, alloy, type of spider, density of wood etc. The units are kN.m/kg.

Spectra fiber 3619
Kevlar 2514
Carbon Fibre 2457
Glass Fibre 1307
Spider Silk 1069
Carbon Epoxy Composite 785
Balsa axial load 521
Steel alloy 254
Aluminium alloy 222
polypropylene 89
Oak 87
Nylon 69
Note that strength and rigidity are different properties, strength is resistance to breaking, rigidity is resistance to bending or stretching.

2- Carbon Fiber is very Rigid

Rigidity or stiffness of a material is measured by its Young Modulus and measures how much a material deflects under stress. Carbon fiber reinforced plastic is over 4 times stiffer than Glass reinforced plastic, almost 20 times more than pine, 2.5 times greater than aluminium. For more information on stiffness and how it is measured, plus a comparison table of different materials see my Young Modulus page.

Also, as a science teacher, I love this amount of detail. Thanks!