Suspiciously high Youngs Modulus

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Dave M
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Suspiciously high Youngs Modulus

Post by Dave M » Tue May 31, 2016 2:57 am

I have been tap testing some Sitka spruce and get the results below. The long grain stiffness seems very high. Is a figure this big likely? I have repeated the tests many times with consistent results.
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Jim watts
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Re: Suspiciously high Youngs Modulus

Post by Jim watts » Tue May 31, 2016 6:36 am

I've found Sitka that stiff before too (statically tested). If you'll notice your density is pretty high, stiffness and density track each other fairly well. That is as the density goes up so does the stiffness, usually.

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Trevor Gore
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Re: Suspiciously high Youngs Modulus

Post by Trevor Gore » Tue May 31, 2016 8:45 am

15 GPa is at the high end of the scale, but not exceptionally so. 15 GPa and 440 kg/m^3 puts it pretty much dead on the regression line of all spruce density vs. Elong.

Dave M
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Re: Suspiciously high Youngs Modulus

Post by Dave M » Tue May 31, 2016 7:27 pm

OK so thanks both. A pretty thin top coming up then. Dave
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kiwigeo
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Re: Suspiciously high Youngs Modulus

Post by kiwigeo » Tue May 31, 2016 7:50 pm

Dave Ive got a bunch of sitka bracing stock that sits around 14-15GPa for Youngs Modulus values.....I measured all my bracing stock after the disasterous top I made using king billy pine bracing.
Martin

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